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rfc:rfc2622

Network Working Group C. Alaettinoglu Request for Comments: 2622 USC/Information Sciences Institute Obsoletes: 2280 C. Villamizar Category: Standards Track Avici Systems

                                                            E. Gerich
                                                      At Home Network
                                                           D. Kessens
                                                 Qwest Communications
                                                             D. Meyer
                                                 University of Oregon
                                                             T. Bates
                                                        Cisco Systems
                                                        D. Karrenberg
                                                             RIPE NCC
                                                          M. Terpstra
                                                         Bay Networks
                                                            June 1999
            Routing Policy Specification Language (RPSL)

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

 RPSL allows a network operator to be able to specify routing policies
 at various levels in the Internet hierarchy; for example at the
 Autonomous System (AS) level.  At the same time, policies can be
 specified with sufficient detail in RPSL so that low level router
 configurations can be generated from them.  RPSL is extensible; new
 routing protocols and new protocol features can be introduced at any
 time.

Alaettinoglu, et al. Standards Track [Page 1] RFC 2622 RPSL June 1999

Table of Contents

 1 Introduction                                                      3
 2 RPSL Names, Reserved Words, and Representation                    4
 3 Contact Information                                               7
   3.1 mntner Class . . . . . . . . . . . . . . . . . . . . . . . .  7
   3.2 person Class . . . . . . . . . . . . . . . . . . . . . . . . 10
   3.3 role Class . . . . . . . . . . . . . . . . . . . . . . . . . 11
 4 route Class                                                      12
 5 Set Classes                                                      13
   5.1 as-set Class . . . . . . . . . . . . . . . . . . . . . . . . 14
   5.2 route-set Class. . . . . . . . . . . . . . . . . . . . . . . 15
   5.3 Predefined Set Objects . . . . . . . . . . . . . . . . . . . 17
   5.4 Filters and filter-set Class . . . . . . . . . . . . . . . . 17
   5.5 rtr-set Class. . . . . . . . . . . . . . . . . . . . . . . . 22
   5.6 Peerings and peering-set Class . . . . . . . . . . . . . . . 24
 6 aut-num Class                                                    27
   6.1 import Attribute:  Import Policy Specification . . . . . . . 27
     6.1.1 Action Specification . . . . . . . . . . . . . . . . . . 28
   6.2 export Attribute:  Export Policy Specification . . . . . . . 29
    6.3 Other Routing Protocols, Multi-Protocol Routing Protocols,
     and Injecting Routes Between Protocols . . . . . . . . . . . . 29
   6.4 Ambiguity Resolution . . . . . . . . . . . . . . . . . . . . 31
   6.5 default Attribute: Default Policy Specification  . . . . . . 33
   6.6 Structured Policy Specification. . . . . . . . . . . . . . . 33
 7 dictionary Class                                                 37
   7.1 Initial RPSL Dictionary and Example Policy Actions and
     Filters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 8 Advanced route Class                                             45
   8.1 Specifying Aggregate Routes. . . . . . . . . . . . . . . . . 45
     8.1.1Interaction with policies in aut-num class. . . . . . . . 49
     8.1.2Ambiguity resolution with overlapping aggregates. . . . . 50
   8.2 Specifying Static Routes . . . . . . . . . . . . . . . . . . 52
 9 inet-rtr Class                                                   52
 10 Extending RPSL                                                  54
   10.1 Extensions by changing the dictionary class . . . . . . . . 54
   10.2 Extensions by adding new attributes to existing classes . . 55
   10.3 Extensions by adding new classes  . . . . . . . . . . . . . 55
   10.4 Extensions by changing the syntax of existing RPSL
      attributes. . . . . . . . . . . . . . . . . . . . . . . . . . 55
 11 Security Considerations                                         56
 12 Acknowledgements                                                56
 References                                                         56
 A Routing Registry Sites                                           59
 B Grammar Rules                                                    59
 C Changes from RFC 2280                                            67
 D Authors' Addresses                                               68
 Full Copyright Statement                                           69

Alaettinoglu, et al. Standards Track [Page 2] RFC 2622 RPSL June 1999

1 Introduction

 This memo is the reference document for the Routing Policy
 Specification Language (RPSL).  RPSL allows a network operator to be
 able to specify routing policies at various levels in the Internet
 hierarchy; for example at the Autonomous System (AS) level.  At the
 same time, policies can be specified with sufficient detail in RPSL
 so that low level router configurations can be generated from them.
 RPSL is extensible; new routing protocols and new protocol features
 can be introduced at any time.
 RPSL is a replacement for the current Internet policy specification
 language known as RIPE-181 [6] or RFC-1786 [7].  RIPE-81 [8] was the
 first language deployed in the Internet for specifying routing
 policies.  It was later replaced by RIPE-181 [6].  Through
 operational use of RIPE-181 it has become apparent that certain
 policies cannot be specified and a need for an enhanced and more
 generalized language is needed.  RPSL addresses RIPE-181's
 limitations.
 RPSL was designed so that a view of the global routing policy can be
 contained in a single cooperatively maintained distributed database
 to improve the integrity of Internet's routing.  RPSL is not designed
 to be a router configuration language.  RPSL is designed so that
 router configurations can be generated from the description of the
 policy for one autonomous system (aut-num class) combined with the
 description of a router (inet-rtr class), mainly providing router ID,
 autonomous system number of the router, interfaces and peers of the
 router, and combined with a global database mappings from AS sets to
 ASes (as-set class), and from origin ASes and route sets to route
 prefixes (route and route-set classes).  The accurate population of
 the RPSL database can help contribute toward such goals as router
 configurations that protect against accidental (or malicious)
 distribution of inaccurate routing information, verification of
 Internet's routing, and aggregation boundaries beyond a single AS.
 RPSL is object oriented; that is, objects contain pieces of policy
 and administrative information.  These objects are registered in the
 Internet Routing Registry (IRR) by the authorized organizations.  The
 registration process is beyond the scope of this document.  Please
 refer to [1, 17, 4] for more details on the IRR.
 In the following sections, we present the classes that are used to
 define various policy and administrative objects.  The "mntner" class
 defines entities authorized to add, delete and modify a set of
 objects.  The "person" and "role" classes describes technical and
 administrative contact personnel.  Autonomous systems (ASes) are
 specified using the "aut-num" class.  Routes are specified using the

Alaettinoglu, et al. Standards Track [Page 3] RFC 2622 RPSL June 1999

 "route" class.  Sets of objects can be defined using the "as-set",
 "route-set", "filter-set", "peering-set", and "rtr-set" classes.  The
 "dictionary" class provides the extensibility to the language.  The
 "inet-rtr" class is used to specify routers.  Many of these classes
 were originally defined in earlier documents [6, 13, 16, 12, 5] and
 have all been enhanced.
 This document is self-contained.  However, the reader is encouraged
 to read RIPE-181 [7] and the associated documents [13, 16, 12, 5] as
 they provide significant background as to the motivation and
 underlying principles behind RIPE-181 and consequently, RPSL. For a
 tutorial on RPSL, the reader should read the RPSL applications
 document [4].

2 RPSL Names, Reserved Words, and Representation

 Each class has a set of attributes which store a piece of information
 about the objects of the class.  Attributes can be mandatory or
 optional: A mandatory attribute has to be defined for all objects of
 the class; optional attributes can be skipped.  Attributes can also
 be single or multiple valued.  Each object is uniquely identified by
 a set of attributes, referred to as the class "key".
 The value of an attribute has a type.  The following types are most
 widely used.  Note that RPSL is case insensitive and only the
 characters from the ASCII character set can be used.
 <object-name>
    Many objects in RPSL have a name.  An <object-name> is made up of
    letters, digits, the character underscore "_", and the character
    hyphen "-"; the first character of a name must be a letter, and
    the last character of a name must be a letter or a digit.  The
    following words are reserved by RPSL, and they can not be used as
    names:
        any as-any rs-any peeras
        and or not
        atomic from to at action accept announce except refine
        networks into inbound outbound
    Names starting with certain prefixes are reserved for certain
    object types.  Names starting with "as-" are reserved for as set
    names.  Names starting with "rs-" are reserved for route set
    names.  Names starting with "rtrs-" are reserved for router set
    names.  Names starting with "fltr-" are reserved for filter set
    names.  Names starting with "prng-" are reserved for peering set
    names.

Alaettinoglu, et al. Standards Track [Page 4] RFC 2622 RPSL June 1999

 <as-number> An AS number x is represented as the string "ASx".  That
    is, the AS 226 is represented as AS226.
 <ipv4-address> An IPv4 address is represented as a sequence of four
    integers in the range from 0 to 255 separated by the character dot
    ".".  For example, 128.9.128.5 represents a valid IPv4 address.
    In the rest of this document, we may refer to IPv4 addresses as IP
    addresses.
 <address-prefix> An address prefix is represented as an IPv4 address
    followed by the character slash "/" followed by an integer in the
    range from 0 to 32.  The following are valid address prefixes:
    128.9.128.5/32, 128.9.0.0/16, 0.0.0.0/0; and the following address
    prefixes are invalid:  0/0, 128.9/16 since 0 or 128.9 are not
    strings containing four integers.
 <address-prefix-range> An address prefix range is an address prefix
    followed by an optional range operator.  The range operators are:
 ^- is the exclusive more specifics operator; it stands for the more
    specifics of the address prefix excluding the address prefix
    itself.  For example, 128.9.0.0/16^- contains all the more
    specifics of 128.9.0.0/16 excluding 128.9.0.0/16.
 ^+ is the inclusive more specifics operator; it stands for the more
    specifics of the address prefix including the address prefix
    itself.  For example, 5.0.0.0/8^+ contains all the more specifics
    of 5.0.0.0/8 including 5.0.0.0/8.
 ^n where n is an integer, stands for all the length n specifics of
    the address prefix.  For example, 30.0.0.0/8^16 contains all the
    more specifics of 30.0.0.0/8 which are of length 16 such as
    30.9.0.0/16.
 ^n-m where n and m are integers, stands for all the length n to
    length m specifics of the address prefix.  For example,
    30.0.0.0/8^24-32 contains all the more specifics of 30.0.0.0/8
    which are of length 24 to 32 such as 30.9.9.96/28.
 Range operators can also be applied to address prefix sets.  In this
 case, they distribute over the members of the set.  For example, for
 a route-set (defined later) rs-foo, rs-foo^+ contains all the
 inclusive more specifics of all the prefixes in rs-foo.
 It is an error to follow a range operator with another one (e.g.
 30.0.0.0/8^24-28^+ is an error).  However, a range operator can be
 applied to an address prefix set that has address prefix ranges in it
 (e.g. {30.0.0.0/8^24-28}^27-30 is not an error).  In this case, the

Alaettinoglu, et al. Standards Track [Page 5] RFC 2622 RPSL June 1999

 outer operator ^n-m distributes over the inner operator ^k-l and
 becomes the operator ^max(n,k)-m if m is greater than or equal to
 max(n,k), or otherwise, the prefix is deleted from the set.  Note
 that the operator ^n is equivalent to ^n-n; prefix/l^+ is equivalent
 to prefix/l^l-32; prefix/l^- is equivalent to prefix/l^(l+1)-32;
 {prefix/l^n-m}^+ is equivalent to {prefix/l^n-32}; and {prefix/l^n-
 m}^- is equivalent to {prefix/l^(n+1)-32}.  For example,
              {128.9.0.0/16^+}^-     == {128.9.0.0/16^-}
              {128.9.0.0/16^-}^+     == {128.9.0.0/16^-}
              {128.9.0.0/16^17}^24   == {128.9.0.0/16^24}
              {128.9.0.0/16^20-24}^26-28 == {128.9.0.0/16^26-28}
              {128.9.0.0/16^20-24}^22-28 == {128.9.0.0/16^22-28}
              {128.9.0.0/16^20-24}^18-28 == {128.9.0.0/16^20-28}
              {128.9.0.0/16^20-24}^18-22 == {128.9.0.0/16^20-22}
              {128.9.0.0/16^20-24}^18-19 == {}
 <date>
    A date is represented as an eight digit integer of the form
    YYYYMMDD where YYYY represents the year, MM represents the month
    of the year (01 through 12), and DD represents the day of the
    month (01 through 31).  All dates are in UTC unless otherwise
    specified.  For example, June 24, 1996 is represented as 19960624.
 <email-address>is as described in RFC-822 [10].
 <dns-name>is as described in RFC-1034 [17].
 <nic-handle> is a uniquely assigned identifier word used by routing,
    address allocation, and other registries to unambiguously refer to
    contact information.  Person and role classes map NIC handles to
    actual person names, and contact information.
 <free-form>is a sequence of ASCII characters.
 <X-name> is a name of an object of type X. That is <mntner-name> is a
    name of a mntner object.
 <registry-name> is a name of an IRR registry.  The routing registries
    are listed in Appendix A.
 A value of an attribute may also be a list of one of these types.  A
 list is represented by separating the list members by commas ",".
 For example, "AS1, AS2, AS3, AS4" is a list of AS numbers.  Note that
 being list valued and being multiple valued are orthogonal.  A
 multiple valued attribute has more than one value, each of which may
 or may not be a list.  On the other hand a single valued attribute
 may have a list value.

Alaettinoglu, et al. Standards Track [Page 6] RFC 2622 RPSL June 1999

 An RPSL object is textually represented as a list of attribute-value
 pairs.  Each attribute-value pair is written on a separate line.  The
 attribute name starts at column 0, followed by character ":" and
 followed by the value of the attribute.  The attribute which has the
 same name as the object's class should be specified first.  The
 object's representation ends when a blank line is encountered.  An
 attribute's value can be split over multiple lines, by having a
 space, a tab or a plus ('+') character as the first character of the
 continuation lines.  The character "+" for line continuation allows
 attribute values to contain blank lines.  More spaces may optionally
 be used after the continuation character to increase readability.
 The order of attribute-value pairs is significant.
 An object's description may contain comments.  A comment can be
 anywhere in an object's definition, it starts at the first "#"
 character on a line and ends at the first end-of-line character.
 White space characters can be used to improve readability.
 An integer can be specified using (1) the C programming language
 notation (e.g. 1, 12345); (2) sequence of four 1-octet integers (in
 the range from 0 to 255) separated by the character dot "."  (e.g.
 1.1.1.1, 255.255.0.0), in this case a 4-octet integer is formed by
 concatenating these 1-octet integers in the most significant to least
 significant order; (3) sequence of two 2-octet integers (in the range
 from 0 to 65535) separated by the character colon ":" (e.g. 3561:70,
 3582:10), in this case a 4-octet integer is formed by concatenating
 these 2-octet integers in the most significant to least significant
 order.

3 Contact Information

 The mntner, person and role classes, admin-c, tech-c, mnt-by,
 changed, and source attributes of all classes describe contact
 information.  The mntner class also specifies authenticaiton
 information required to create, delete and update other objects.
 These classes do not specify routing policies and each registry may
 have different or additional requirements on them.  Here we present
 the common denominator for completeness which is the RIPE database
 implementation [16].  Please consult your routing registry for the
 latest specification of these classes and attributes.  The "Routing
 Policy System Security" document [20] describes the authenticaiton
 and authorization model in more detail.

3.1 mntner Class

 The mntner class specifies authenticaiton information required to
 create, delete and update RPSL objects.  A provider, before he/she
 can create RPSL objects, first needs to create a mntner object.  The

Alaettinoglu, et al. Standards Track [Page 7] RFC 2622 RPSL June 1999

 attributes of the mntner class are shown in Figure 1.  The mntner
 class was first described in [13].
 The mntner attribute is mandatory and is the class key.  Its value is
 an RPSL name.  The auth attribute specifies the scheme that will be
 used to identify and authenticate update requests from this
 maintainer.  It has the following syntax:
 auth: <scheme-id> <auth-info>
 E.g.
        auth: NONE
Attribute  Value                   Type
mntner     <object-name>           mandatory, single-valued, class key
descr      <free-form>             mandatory, single-valued
auth       see description in text mandatory, multi-valued
upd-to     <email-address>         mandatory, multi-valued
mnt-nfy    <email-address>         optional, multi-valued
tech-c     <nic-handle>            mandatory, multi-valued
admin-c    <nic-handle>            optional, multi-valued
remarks    <free-form>             optional, multi-valued
notify     <email-address>         optional, multi-valued
mnt-by     list of <mntner-name>   mandatory, multi-valued
changed    <email-address> <date>  mandatory, multi-valued
source     <registry-name>         mandatory, single-valued
                   Figure 1:  mntner Class Attributes
        auth: CRYPT-PW dhjsdfhruewf
        auth: MAIL-FROM .*@ripe\.net
 The <scheme-id>'s currently defined are: NONE, MAIL-FROM, PGP-KEY and
 CRYPT-PW. The <auth-info> is additional information required by a
 particular scheme: in the case of MAIL-FROM, it is a regular
 expression matching valid email addresses; in the case of CRYPT-PW,
 it is a password in UNIX crypt format; and in the case of PGP-KEY, it
 is a pointer to key-certif object [22] containing the PGP public key
 of the user.  If multiple auth attributes are specified, an update
 request satisfying any one of them is authenticated to be from the
 maintainer.
 The upd-to attribute is an email address.  On an unauthorized update
 attempt of an object maintained by this maintainer, an email message
 will be sent to this address.  The mnt-nfy attribute is an email
 address.  A notification message will be forwarded to this email

Alaettinoglu, et al. Standards Track [Page 8] RFC 2622 RPSL June 1999

 address whenever an object maintained by this maintainer is added,
 changed or deleted.
 The descr attribute is a short, free-form textual description of the
 object.  The tech-c attribute is a technical contact NIC handle.
 This is someone to be contacted for technical problems such as
 misconfiguration.  The admin-c attribute is an administrative contact
 NIC handle.  The remarks attribute is a free text explanation or
 clarification.  The notify attribute is an email address to which
 notifications of changes to this object should be sent.  The mnt-by
 attribute is a list of mntner object names.  The authorization for
 changes to this object is governed by any of the maintainer objects
 referenced.  The changed attribute documents who last changed this
 object, and when this change was made.  Its syntax has the following
 form:
 changed: <email-address> <YYYYMMDD>
 E.g.
 changed: johndoe@terabit-labs.nn 19900401
 The <email-address> identifies the person who made the last change.
 <YYYYMMDD> is the date of the change.  The source attribute specifies
 the registry where the object is registered.  Figure 2 shows an
 example mntner object.  In the example, UNIX crypt format password
 authentication is used.
 mntner:      RIPE-NCC-MNT
 descr:       RIPE-NCC Maintainer
 admin-c:     DK58
 tech-c:      OPS4-RIPE
 upd-to:      ops@ripe.net
 mnt-nfy:     ops-fyi@ripe.net
 auth:        CRYPT-PW lz1A7/JnfkTtI
 mnt-by:      RIPE-NCC-MNT
 changed:     ripe-dbm@ripe.net 19970820
 source:      RIPE
                  Figure 2:  An example mntner object.
 The descr, tech-c, admin-c, remarks, notify, mnt-by, changed and
 source attributes are attributes of all RPSL classes.  Their syntax,
 semantics, and mandatory, optional, multi-valued, or single-valued
 status are the same for for all RPSL classes.  Only exception to this
 is the admin-c attribute which is mandatory for the aut-num class.
 We do not further discuss them in other sections.

Alaettinoglu, et al. Standards Track [Page 9] RFC 2622 RPSL June 1999

3.2 person Class

 A person class is used to describe information about people.  Even
 though it does not describe routing policy, we still describe it here
 briefly since many policy objects make reference to person objects.
 The person class was first described in [15].
 The attributes of the person class are shown in Figure 3.  The person
 attribute is the full name of the person.  The phone and the fax-no
 attributes have the following syntax:
    phone: +<country-code> <city> <subscriber> [ext. <extension>]
 E.g.:
    phone: +31 20 12334676
Attribute  Value                   Type
person     <free-form>             mandatory, single-valued
nic-hdl    <nic-handle>            mandatory, single-valued, class key
address    <free-form>             mandatory, multi-valued
phone      see description in text mandatory, multi-valued
fax-no     same as phone           optional, multi-valued
e-mail     <email-address>         mandatory, multi-valued
                   Figure 3:  person Class Attributes
    phone: +44 123 987654 ext. 4711
 Figure 4 shows an example person object.
 person:      Daniel Karrenberg
 address:     RIPE Network Coordination Centre (NCC)
 address:     Singel 258
 address:     NL-1016 AB  Amsterdam
 address:     Netherlands
 phone:       +31 20 535 4444
 fax-no:      +31 20 535 4445
 e-mail:      Daniel.Karrenberg@ripe.net
 nic-hdl:     DK58
 changed:     Daniel.Karrenberg@ripe.net 19970616
 source:      RIPE
                  Figure 4:  An example person object.

Alaettinoglu, et al. Standards Track [Page 10] RFC 2622 RPSL June 1999

3.3 role Class

 The role class is similar to the person object.  However, instead of
 describing a human being, it describes a role performed by one or
 more human beings.  Examples include help desks, network monitoring
 centers, system administrators, etc.  Role object is particularly
 useful since often a person performing a role may change, however the
 role itself remains.
 The attributes of the role class are shown in Figure 5.  The nic-hdl
 attributes of the person and role classes share the same name space.
 The trouble attribute of role object may contain additional contact
 information to be used when a problem arises in any object that
 references this role object.  Figure 6 shows an example role object.
Attribute  Value                    Type
role       <free-form>              mandatory, single-valued
nic-hdl    <nic-handle>             mandatory, single-valued,
                                    class key
trouble    <free-form>              optional, multi-valued
address    <free-form>              mandatory, multi-valued
phone      see description in text  mandatory, multi-valued
fax-no     same as phone            optional, multi-valued
e-mail     <email-address>          mandatory, multi-valued
                    Figure 5:  role Class Attributes
 role:        RIPE NCC Operations
 trouble:
 address:     Singel 258
 address:     1016 AB Amsterdam
 address:     The Netherlands
 phone:       +31 20 535 4444
 fax-no:      +31 20 545 4445
 e-mail:      ops@ripe.net
 admin-c:     CO19-RIPE
 tech-c:      RW488-RIPE
 tech-c:      JLSD1-RIPE
 nic-hdl:     OPS4-RIPE
 notify:      ops@ripe.net
 changed:     roderik@ripe.net 19970926
 source:      RIPE
                   Figure 6:  An example role object.

Alaettinoglu, et al. Standards Track [Page 11] RFC 2622 RPSL June 1999

4 route Class

 Each interAS route (also referred to as an interdomain route)
 originated by an AS is specified using a route object.  The
 attributes of the route class are shown in Figure 7.  The route
 attribute is the address prefix of the route and the origin attribute
 is the AS number of the AS that originates the route into the interAS
 routing system.  The route and origin attribute pair is the class
 key.
 Figure 8 shows examples of four route objects (we do not include
 contact attributes such as admin-c, tech-c for brevity).  Note that
 the last two route objects have the same address prefix, namely
 128.8.0.0/16.  However, they are different route objects since they
 are originated by different ASes (i.e. they have different keys).
 Attribute     Value                      Type
 route         <address-prefix>           mandatory, single-valued,
                                          class key
 origin        <as-number>                mandatory, single-valued,
                                          class key
 member-of     list of <route-set-names>  optional, multi-valued
               see Section 5
 inject        see Section 8              optional, multi-valued
 components    see Section 8              optional, single-valued
 aggr-bndry    see Section 8              optional, single-valued
 aggr-mtd      see Section 8              optional, single-valued
 export-comps  see Section 8              optional, single-valued
 holes         see Section 8              optional, multi-valued
                      Figure 7:  route Class Attributes
    route: 128.9.0.0/16
    origin: AS226
    route: 128.99.0.0/16
    origin: AS226
    route: 128.8.0.0/16
    origin: AS1
    route: 128.8.0.0/16
    origin: AS2
                           Figure 8:  Route Objects

Alaettinoglu, et al. Standards Track [Page 12] RFC 2622 RPSL June 1999

5 Set Classes

 To specify policies, it is often useful to define sets of objects.
 For this purpose we define as-set, route-set, rtr-set, filter-set,
 and peering-set classes.  These classes define a named set.  The
 members of these sets can be specified either directly by listing
 them in the sets' definition, or indirectly by having member objects
 refer to the sets' names, or a combination of both methods.
 A set's name is an rpsl word with the following restrictions: All
 as-set names start with prefix "as-".  All route-set names start with
 prefix "rs-".  All rtr-set names start with prefix "rtrs-".  All
 filter-set names start with prefix "fltr-".  All peering-set names
 start with prefix "prng-".  For example, as-foo is a valid as-set
 name.
 Set names can also be hierarchical.  A hierarchical set name is a
 sequence of set names and AS numbers separated by colons ":".  At
 least one component of such a name must be an actual set name (i.e.
 start with one of the prefixes above).  All the set name components
 of an hierarchical name has to be of the same type.  For example, the
 following names are valid: AS1:AS-CUSTOMERS, AS1:RS-EXPORT:AS2, RS-
 EXCEPTIONS:RS-BOGUS.
 The purpose of an hierarchical set name is to partition the set name
 space so that the maintainers of the set X1 controls the whole set
 name space underneath, i.e. X1:...:Xn-1.  Thus, a set object with
 name X1:...:Xn-1:Xn can only be created by the maintainer of the
 object with name X1:...:Xn-1.  That is, only the maintainer of AS1
 can create a set with name AS1:AS-FOO; and only the maintainer of
 AS1:AS-FOO can create a set with name AS1:AS-FOO:AS-BAR. Please see
 RPS Security Document [20] for details.

Alaettinoglu, et al. Standards Track [Page 13] RFC 2622 RPSL June 1999

5.1 as-set Class

 The attributes of the as-set class are shown in Figure 9.  The as-set
 attribute defines the name of the set.  It is an RPSL name that
 starts with "as-".  The members attribute lists the members of the
 set.  The members attribute is a list of AS numbers, or other as-set
 names.
    Attribute    Value                    Type
    as-set       <object-name>            mandatory, single-valued,
                                          class key
    members      list of <as-numbers> or  optional, multi-valued
                 <as-set-names>
    mbrs-by-ref  list of <mntner-names>   optional, multi-valued
                   Figure 9:  as-set Class Attributes
 Figure 10 presents two as-set objects.  The set as-foo contains two
 ASes, namely AS1 and AS2.  The set as-bar contains the members of the
 set as-foo and AS3, that is it contains AS1, AS2, AS3.  The set as-
 empty contains no members.

as-set: as-foo as-set: as-bar as-set: as-empty members: AS1, AS2 members: AS3, as-foo

                      Figure 10:  as-set objects.
 The mbrs-by-ref attribute is a list of maintainer names or the
 keyword ANY.  If this attribute is used, the AS set also includes
 ASes whose aut-num objects are registered by one of these maintainers
 and whose member-of attribute refers to the name of this AS set.  If
 the value of a mbrs-by-ref attribute is ANY, any AS object referring
 to the AS set is a member of the set.  If the mbrs-by-ref attribute
 is missing, only the ASes listed in the members attribute are members
 of the set.
  as-set: as-foo
  members: AS1, AS2
  mbrs-by-ref: MNTR-ME
  aut-num: AS3                          aut-num: AS4
  member-of: as-foo                     member-of: as-foo
  mnt-by: MNTR-ME                       mnt-by: MNTR-OTHER
                         Figure 11:  as-set objects.

Alaettinoglu, et al. Standards Track [Page 14] RFC 2622 RPSL June 1999

 Figure 11 presents an example as-set object that uses the mbrs-by-ref
 attribute.  The set as-foo contains AS1, AS2 and AS3.  AS4 is not a
 member of the set as-foo even though the aut-num object references
 as-foo.  This is because MNTR-OTHER is not listed in the as-foo's
 mbrs-by-ref attribute.

5.2 route-set Class

 The attributes of the route-set class are shown in Figure 12.  The
 route-set attribute defines the name of the set.  It is an RPSL name
 that starts with "rs-".  The members attribute lists the members of
 the set.  The members attribute is a list of address prefixes or
 other route-set names.  Note that, the route-set class is a set of
 route prefixes, not of RPSL route objects.

Attribute Value Type route-set <object-name> mandatory,

                                               single-valued,
                                               class key

members list of <address-prefix-range> or optional, multi-valued

            <route-set-name> or
            <route-set-name><range-operator>

mbrs-by-ref list of <mntner-names> optional, multi-valued

                 Figure 12:  route-set Class Attributes
 Figure 13 presents some example route-set objects.  The set rs-foo
 contains two address prefixes, namely 128.9.0.0/16 and 128.9.0.0/24.
 The set rs-bar contains the members of the set rs-foo and the address
 prefix 128.7.0.0/16.
 An address prefix or a route-set name in a members attribute can be
 optionally followed by a range operator.  For example, the following
 set:
 route-set: rs-foo
 members: 128.9.0.0/16, 128.9.0.0/24
 route-set: rs-bar
 members: 128.7.0.0/16, rs-foo
                     Figure 13:  route-set Objects

Alaettinoglu, et al. Standards Track [Page 15] RFC 2622 RPSL June 1999

 route-set: rs-bar
 members: 5.0.0.0/8^+, 30.0.0.0/8^24-32, rs-foo^+
 contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all
 the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as
 30.9.9.96/28, and all the more specifics of address prefixes in route
 set rs-foo.
 The mbrs-by-ref attribute is a list of maintainer names or the
 keyword ANY.  If this attribute is used, the route set also includes
 address prefixes whose route objects are registered by one of these
 maintainers and whose member-of attribute refers to the name of this
 route set.  If the value of a mbrs-by-ref attribute is ANY, any route
 object referring to the route set name is a member.  If the mbrs-by-
 ref attribute is missing, only the address prefixes listed in the
 members attribute are members of the set.
 route-set: rs-foo
 mbrs-by-ref: MNTR-ME, MNTR-YOU
 route-set: rs-bar
 members: 128.7.0.0/16
 mbrs-by-ref: MNTR-YOU
 route: 128.9.0.0/16
 origin: AS1
 member-of: rs-foo
 mnt-by: MNTR-ME
 route: 128.8.0.0/16
 origin: AS2
 member-of: rs-foo, rs-bar
 mnt-by: MNTR-YOU
                     Figure 14:  route-set objects.
 Figure 14 presents example route-set objects that use the mbrs-by-ref
 attribute.  The set rs-foo contains two address prefixes, namely
 128.8.0.0/16 and 128.9.0.0/16 since the route objects for
 128.8.0.0/16 and 128.9.0.0/16 refer to the set name rs-foo in their
 member-of attribute.  The set rs-bar contains the address prefixes
 128.7.0.0/16 and 128.8.0.0/16.  The route 128.7.0.0/16 is explicitly
 listed in the members attribute of rs-bar, and the route object for
 128.8.0.0/16 refer to the set name rs-bar in its member-of attribute.

Alaettinoglu, et al. Standards Track [Page 16] RFC 2622 RPSL June 1999

 Note that, if an address prefix is listed in a members attribute of a
 route set, it is a member of that route set.  The route object
 corresponding to this address prefix does not need to contain a
 member-of attribute referring to this set name.  The member-of
 attribute of the route class is an additional mechanism for
 specifying the members indirectly.

5.3 Predefined Set Objects

 In a context that expects a route set (e.g.  members attribute of the
 route-set class), an AS number ASx defines the set of routes that are
 originated by ASx; and an as-set AS-X defines the set of routes that
 are originated by the ASes in AS-X. A route p is said to be
 originated by ASx if there is a route object for p with ASx as the
 value of the origin attribute.  For example, in Figure 15, the route
 set rs-special contains 128.9.0.0/16, routes of AS1 and AS2, and
 routes of the ASes in AS set AS-FOO.
 route-set: rs-special
 members: 128.9.0.0/16, AS1, AS2, AS-FOO
        Figure 15:  Use of AS numbers and AS sets in route sets.
 The set rs-any contains all routes registered in IRR. The set as-any
 contains all ASes registered in IRR.

5.4 Filters and filter-set Class

 The attributes of the filter-set class are shown in Figure 16.  A
 filter-set object defines a set of routes that are matched by its
 filter.  The filter-set attribute defines the name of the filter.  It
 is an RPSL name that starts with "fltr-".
     Attribute   Value         Type
     filter-set  <object-name> mandatory, single-valued, class key
     filter      <filter>      mandatory, single-valued
                  Figure 16:  filter Class Attributes
    filter-set: fltr-foo
    filter: { 5.0.0.0/8, 6.0.0.0/8 }
    filter-set: fltr-bar
    filter: (AS1 or fltr-foo) and <AS2>
                    Figure 17:  filter-set objects.

Alaettinoglu, et al. Standards Track [Page 17] RFC 2622 RPSL June 1999

 The filter attribute defines the set's policy filter.  A policy
 filter is a logical expression which when applied to a set of routes
 returns a subset of these routes.  We say that the policy filter
 matches the subset returned.  The policy filter can match routes
 using any BGP path attribute, such as the destination address prefix
 (or NLRI), AS-path, or community attributes.
 The policy filters can be composite by using the operators AND, OR,
 and NOT.  The following policy filters can be used to select a subset
 of routes:
 ANY
    The keyword ANY matches all routes.
 Address-Prefix Set This is an explicit list of address prefixes
    enclosed in braces '{' and '}'.  The policy filter matches the set
    of routes whose destination address-prefix is in the set.  For
    example:
      { 0.0.0.0/0 }
      { 128.9.0.0/16, 128.8.0.0/16, 128.7.128.0/17, 5.0.0.0/8 }
      { }
 An address prefix can be optionally followed by a range operator
 (i.e.
    { 5.0.0.0/8^+, 128.9.0.0/16^-, 30.0.0.0/8^16, 30.0.0.0/8^24-32 }
 contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all
 the more specifics of 128.9.0.0/16 excluding 128.9.0.0/16, all the
 more specifics of 30.0.0.0/8 which are of length 16 such as
 30.9.0.0/16, and all the more specifics of 30.0.0.0/8 which are of
 length 24 to 32 such as 30.9.9.96/28.
 Route Set Name  A route set name matches the set of routes that are
 members of the set.  A route set name may be a name of a route-set
 object, an AS number, or a name of an as-set object (AS numbers and
 as-set names implicitly define route sets; please see Section 5.3).
 For example:
    aut-num: AS1
    import: from AS2 accept AS2
    import: from AS2 accept AS-FOO
    import: from AS2 accept RS-FOO

Alaettinoglu, et al. Standards Track [Page 18] RFC 2622 RPSL June 1999

 The keyword PeerAS can be used instead of the AS number of the peer
 AS.  PeerAS is particularly useful when the peering is specified
 using an AS expression.  For example:
    as-set: AS-FOO
    members: AS2, AS3
    aut-num: AS1
    import: from AS-FOO accept PeerAS
 is same as:
    aut-num: AS1
    import: from AS2 accept AS2
    import: from AS3 accept AS3
 A route set name can also be followed by one of the operators '^-',
 '^+', example, { 5.0.0.0/8, 6.0.0.0/8 }^+ equals { 5.0.0.0/8^+,
 6.0.0.0/8^+ }, and AS1^- equals all the exclusive more specifics of
 routes originated by AS1.
 AS Path Regular Expressions
    An AS-path regular expression can be used as a policy filter by
    enclosing the expression in `<' and `>'.  An AS-path policy filter
    matches the set of routes which traverses a sequence of ASes
    matched by the AS-path regular expression.  A router can check
    this using the AS_PATH attribute in the Border Gateway Protocol
    [19], or the RD_PATH attribute in the Inter-Domain Routing
    Protocol [18].
    AS-path Regular Expressions are POSIX compliant regular
    expressions over the alphabet of AS numbers.  The regular
    expression constructs are as follows:
 ASN
    where ASN is an AS number.  ASN matches the AS-path that is of
    length 1 and contains the corresponding AS number (e.g.  AS-path
    regular expression AS1 matches the AS-path "1").
    The keyword PeerAS can be used instead of the AS number of the
    peer AS.
 AS-set
    where AS-set is an AS set name.  AS-set matches the AS-paths that
    is matched by one of the ASes in the AS-set.
 .
    matches the AS-paths matched by any AS number.

Alaettinoglu, et al. Standards Track [Page 19] RFC 2622 RPSL June 1999

 [...]
    is an AS number set.  It matches the AS-paths matched by the AS
    numbers listed between the brackets.  The AS numbers in the set
    are separated by white space characters.  If a `-' is used between
    two AS numbers in this set, all AS numbers between the two AS
    numbers are included in the set.  If an as-set name is listed, all
    AS numbers in the as-set are included.
 [^...]
    is a complemented AS number set.  It matches any AS-path which is
    not matched by the AS numbers in the set.
 ^
    Matches the empty string at the beginning of an AS-path.
 $
    Matches the empty string at the end of an AS-path.
 We next list the regular expression operators in the decreasing order
 of evaluation.  These operators are left associative, i.e. performed
 left to right.
 Unary postfix operators * + ?  {m} {m,n} {m,}
    For a regular expression A, A* matches zero or more occurrences of
    A; A+ matches one or more occurrences of A; A?  matches zero or
    one occurrence of A; A{m} matches m occurrence of A; A{m,n}
    matches m to n occurrence of A; A{m,} matches m or more occurrence
    of A. For example, [AS1 AS2]{2} matches AS1 AS1, AS1 AS2, AS2 AS1,
    and AS2 AS2.
 Unary postfix operators ~* ~+ ~{m} ~{m,n} ~{m,}
    These operators have similar functionality as the corresponding
    operators listed above, but all occurrences of the regular
    expression has to match the same pattern.  For example, [AS1
    AS2]~{2} matches AS1 AS1 and AS2 AS2, but it does not match AS1
    AS2 and AS2 AS1.
 Binary catenation operator
    This is an implicit operator and exists between two regular
    expressions A and B when no other explicit operator is specified.
    The resulting expression A B matches an AS-path if A matches some
    prefix of the AS-path and B matches the rest of the AS-path.
 Binary alternative (or) operator |
    For a regular expressions A and B, A | B matches any AS-path that
    is matched by A or B.

Alaettinoglu, et al. Standards Track [Page 20] RFC 2622 RPSL June 1999

 Parenthesis can be used to override the default order of evaluation.
 White spaces can be used to increase readability.
 The following are examples of AS-path filters:
 <AS3>
 <^AS1>
 <AS2$>
 <^AS1 AS2 AS3$>
 <^AS1 .* AS2$>.
 The first example matches any route whose AS-path contains AS3, the
 second matches routes whose AS-path starts with AS1, the third
 matches routes whose AS-path ends with AS2, the fourth matches routes
 whose AS-path is exactly "1 2 3", and the fifth matches routes whose
 AS-path starts with AS1 and ends in AS2 with any number of AS numbers
 in between.
 Composite Policy Filters The following operators (in decreasing order
 of evaluation) can be used to form composite policy filters:
 NOT Given a policy filter x, NOT x matches the set of routes that
     are not matched by x.  That is it is the negation of policy
     filter x.
 AND Given two policy filters x and y, x AND y matches the intersection
     of the routes that are matched by x and that are matched by y.
 OR  Given two policy filters x and y, x OR y matches the union of the
     routes that are matched by x and that are matched by y.
 Note that an OR operator can be implicit, that is `x y' is equivalent
 to `x OR y'.
E.g.
  NOT {128.9.0.0/16, 128.8.0.0/16}
  AS226 AS227 OR AS228
  AS226 AND NOT {128.9.0.0/16}
  AS226 AND {0.0.0.0/0^0-18}
 The first example matches any route except 128.9.0.0/16 and
 128.8.0.0/16.  The second example matches the routes of AS226, AS227
 and AS228.  The third example matches the routes of AS226 except
 128.9.0.0/16.  The fourth example matches the routes of AS226 whose
 length are not longer than 18.

Alaettinoglu, et al. Standards Track [Page 21] RFC 2622 RPSL June 1999

 Routing Policy Attributes Policy filters can also use the values of
 other attributes for comparison.  The attributes whose values can be
 used in policy filters are specified in the RPSL dictionary.  Please
 refer to Section 7 for details.  An example using the the BGP
 community attribute is shown below:
  aut-num: AS1
  export: to AS2 announce AS1 AND NOT community(NO_EXPORT)
 Filters using the routing policy attributes defined in the dictionary
 are evaluated before evaluating the operators AND, OR and NOT.
 Filter Set Name
    A filter set name matches the set of routes that are matched by
    its filter attribute.  Note that the filter attribute of a filter
    set, can recursively refer to other filter set names.  For example
    in Figure 17, fltr-foo matches { 5.0.0.0/8, 6.0.0.0/8 }, and
    fltr-bar matches AS1'S routes or { 5.0.0.0/8, 6.0.0.0/8 } if their
    as path contained AS2.

5.5 rtr-set Class

 The attributes of the rtr-set class are shown in Figure 18.  The
 rtr-set attribute defines the name of the set.  It is an RPSL name
 that starts with "rtrs-".  The members attribute lists the members of
 the set.  The members attribute is a list of inet-rtr names,
 ipv4_addresses or other rtr-set names.
  Attribute    Value                        Type
  rtr-set      <object-name>                mandatory, single-valued,
                                            class key
  members      list of <inet-rtr-names> or  optional, multi-valued
               <rtr-set-names>
               or <ipv4_addresses>
  mbrs-by-ref  list of <mntner-names>       optional, multi-valued
                  Figure 18:  rtr-set Class Attributes

Alaettinoglu, et al. Standards Track [Page 22] RFC 2622 RPSL June 1999

 Figure 19 presents two rtr-set objects.  The set rtrs-foo contains
 two routers, namely rtr1.isp.net and rtr2.isp.net.  The set rtrs-bar
 contains the members of the set rtrs-foo and rtr3.isp.net, that is it
 contains rtr1.isp.net, rtr2.isp.net, rtr3.isp.net.

rtr-set: rtrs-foo rtr-set: rtrs-bar members: rtr1.isp.net, rtr2.isp.net members: rtr3.isp.net, rtrs-foo

                      Figure 19:  rtr-set objects.
 The mbrs-by-ref attribute is a list of maintainer names or the
 keyword ANY.  If this attribute is used, the router set also includes
 routers whose inet-rtr objects are registered by one of these
 maintainers and whose member-of attribute refers to the name of this
 router set.  If the value of a mbrs-by-ref attribute is ANY, any
 inet-rtr object referring to the router set is a member of the set.
 If the mbrs-by-ref attribute is missing, only the routers listed in
 the members attribute are members of the set.
     rtr-set: rtrs-foo
     members: rtr1.isp.net, rtr2.isp.net
     mbrs-by-ref: MNTR-ME
     inet-rtr: rtr3.isp.net
     local-as: as1
     ifaddr: 1.1.1.1 masklen 30
     member-of: rtrs-foo
     mnt-by: MNTR-ME
                            Figure 20:  rtr-set objects.
 Figure 20 presents an example rtr-set object that uses the mbrs-by-
 ref attribute.  The set rtrs-foo contains rtr1.isp.net, rtr2.isp.net
 and rtr3.isp.net.

Alaettinoglu, et al. Standards Track [Page 23] RFC 2622 RPSL June 1999

5.6 Peerings and peering-set Class

 The attributes of the peering-set class are shown in Figure 21.  A
 peering-set object defines a set of peerings that are listed in its
 peering attributes.  The peering-set attribute defines the name of
 the set.  It is an RPSL name that starts with "prng-".
    Attribute    Value          Type
    peering-set  <object-name>  mandatory, single-valued, class key
    peering      <peering>      mandatory, multi-valued
                  Figure 21:  filter Class Attributes
 The peering attribute defines a peering that can be used for
 importing or
  1. ——————— ———————-

| 7.7.7.1 |——-| |——-| 7.7.7.2 |

   |                    |     ========      |                    |
   |   AS1              |      EX1  |-------| 7.7.7.3     AS2    |
   |                    |                   |                    |
   |            9.9.9.1 |------       ------| 9.9.9.2            |
   ----------------------     |       |     ----------------------
                             ===========
                                 |    EX2
   ----------------------        |
   |            9.9.9.3 |---------
   |                    |
   |   AS3              |
   ----------------------
Figure 22: Example topology consisting of three ASes, AS1, AS2, and
      AS3; two exchange points, EX1 and EX2; and six routers.
 exporting routes.
    In describing peerings, we are going to use the topology of Figure
    22.  In this topology, there are three ASes, AS1, AS2, and AS3;
    two exchange points, EX1 and EX2; and six routers.  Routers
    connected to the same exchange point peer with each other and
    exchange routing information.  That is, 7.7.7.1, 7.7.7.2 and
    7.7.7.3 peer with each other; 9.9.9.1, 9.9.9.2 and 9.9.9.3 peer
    with each other.
    The syntax of a peering specification is:
    <as-expression> [<router-expression-1>] [at <router-expression-2>]
   | <peering-set-name>

Alaettinoglu, et al. Standards Track [Page 24] RFC 2622 RPSL June 1999

    where <as-expression> is an expression over AS numbers and AS sets
    using operators AND, OR, and EXCEPT, and <router-expression-1> and
    <router-expression-2> are expressions over router IP addresses,
    inet-rtr names, and rtr-set names using operators AND, OR, and
    EXCEPT.  The binary "EXCEPT" operator is the set subtraction
    operator and has the same precedence as the operator AND (it is
    semantically equivalent to "AND NOT" combination).  That is "(AS1
    OR AS2) EXCEPT AS2" equals "AS1".
    This form identifies all the peerings between any local router in
    <router-expression-2> to any of their peer routers in <router-
    expression-1> in the ASes in <as-expression>.  If <router-
    expression-2> is not specified, it defaults to all routers of the
    local AS that peer with ASes in <as-expression>.  If <router-
    expression-1> is not specified, it defaults to all routers of the
    peer ASes in <as-expression> that peer with the local AS.
    If a <peering-set-name> is used, the peerings are listed in the
    corresponding peering-set object.  Note that the peering-set
    objects can be recursive.
    Many special forms of this general peering specification is
    possible.  The following examples illustrate the most common
    cases, using the import attribute of the aut-num class.  In the
    following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2.

(1) aut-num: AS1

   import: from AS2 7.7.7.2 at 7.7.7.1 accept { 128.9.0.0/16 }
 In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2
 and 7.7.7.3.

(2) aut-num: AS1

   import: from AS2 at 7.7.7.1 accept { 128.9.0.0/16 }
 In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2
 and 7.7.7.3, and 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2.

(3) aut-num: AS1

   import: from AS2 accept { 128.9.0.0/16 }
 In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2
 and 9.9.9.3.

Alaettinoglu, et al. Standards Track [Page 25] RFC 2622 RPSL June 1999

(4) as-set: AS-FOO

   members: AS2, AS3
   aut-num: AS1
   import: from AS-FOO      at 9.9.9.1 accept { 128.9.0.0/16 }
 In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2
 and 9.9.9.3, and 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and
 7.7.7.3.

(5) aut-num: AS1

   import: from AS-FOO                 accept { 128.9.0.0/16 }
 In the following example AS1 imports 128.9.0.0/16 from AS3 at router
 9.9.9.1

(6) aut-num: AS1

   import: from AS-FOO and not AS2 at not 7.7.7.1
           accept { 128.9.0.0/16 }
 This is because "AS-FOO and not AS2" equals AS3 and "not 7.7.7.1"
 equals 9.9.9.1.
 In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2
 and 9.9.9.3.

(7) peering-set: prng-bar

   peering: AS1 at 9.9.9.1
   peering-set: prng-foo
   peering: prng-bar
   peering: AS2 at 9.9.9.1
   aut-num: AS1
   import: from prng-foo accept { 128.9.0.0/16 }

Alaettinoglu, et al. Standards Track [Page 26] RFC 2622 RPSL June 1999

6 aut-num Class

 Routing policies are specified using the aut-num class.  The
 attributes of the aut-num class are shown in Figure 23.  The value of
 the aut-num attribute is the AS number of the AS described by this
 object.  The as-name attribute is a symbolic name (in RPSL name
 syntax) of the AS. The import, export and default routing policies of
 the AS are specified using import, export and default attributes
 respectively.
 Attribute  Value                  Type
 aut-num    <as-number>            mandatory, single-valued, class key
 as-name    <object-name>          mandatory, single-valued
 member-of  list of <as-set-names> optional, multi-valued
 import     see Section 6.1        optional, multi valued
 export     see Section 6.2        optional, multi valued
 default    see Section 6.5        optional, multi valued
                  Figure 23:  aut-num Class Attributes

6.1 import Attribute: Import Policy Specification

 In RPSL, an import policy is divided into import policy expressions.
 Each import policy expression is specified using an import attribute.
 The import attribute has the following syntax (we will extend this
 syntax later in Sections 6.3 and 6.6):
 import: from <peering-1> [action <action-1>]
          . . .
          from <peering-N> [action <action-N>]
          accept <filter>
 The action specification is optional.  The semantics of an import
 attribute is as follows: the set of routes that are matched by
 <filter> are imported from all the peers in <peerings>; while
 importing routes at <peering-M>, <action-M> is executed.
E.g.
  aut-num: AS1
  import: from AS2 action pref = 1; accept { 128.9.0.0/16 }
 This example states that the route 128.9.0.0/16 is accepted from AS2
 with preference 1.  We already presented how peerings (see Section
 5.6) and filters (see Section 5.4) are specified.  We next present
 how to specify actions.

Alaettinoglu, et al. Standards Track [Page 27] RFC 2622 RPSL June 1999

6.1.1 Action Specification

 Policy actions in RPSL either set or modify route attributes, such as
 assigning a preference to a route, adding a BGP community to the BGP
 community path attribute, or setting the MULTI-EXIT-DISCRIMINATOR
 attribute.  Policy actions can also instruct routers to perform
 special operations, such as route flap damping.
 The routing policy attributes whose values can be modified in policy
 actions are specified in the RPSL dictionary.  Please refer to
 Section 7 for a list of these attributes.  Each action in RPSL is
 terminated by the semicolon character (';').  It is possible to form
 composite policy actions by listing them one after the other.  In a
 composite policy action, the actions are executed left to right.  For
 example,

aut-num: AS1 import: from AS2

       action pref = 10; med = 0; community.append(10250, 3561:10);
       accept { 128.9.0.0/16 }
 sets pref to 10, med to 0, and then appends 10250 and 3561:10 to the
 BGP community path attribute.  The pref attribute is the inverse of
 the local-pref attribute (i.e. local-pref == 65535 - pref).  A route
 with a local-pref attribute is always preferred over a route without
 one.

aut-num: AS1 import: from AS2 action pref = 1;

       from AS3 action pref = 2;
       accept AS4
 The above example states that AS4's routes are accepted from AS2 with
 preference 1, and from AS3 with preference 2 (routes with lower
 integer preference values are preferred over routes with higher
 integer preference values).

aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1;

       from AS2                    action pref = 2;
       accept AS4
 The above example states that AS4's routes are accepted from AS2 on
 peering 7.7.7.1-7.7.7.2 with preference 1, and on any other peering
 with AS2 with preference 2.

Alaettinoglu, et al. Standards Track [Page 28] RFC 2622 RPSL June 1999

6.2 export Attribute: Export Policy Specification

 Similarly, an export policy expression is specified using an export
 attribute.  The export attribute has the following syntax:
  export: to <peering-1> [action <action-1>]
          . . .
          to <peering-N> [action <action-N>]
          announce <filter>
 The action specification is optional.  The semantics of an export
 attribute is as follows:  the set of routes that are matched by
 <filter> are exported to all the peers specified in <peerings>; while
 exporting routes at <peering-M>, <action-M> is executed.
E.g.
  aut-num: AS1
  export: to AS2 action med = 5; community .= { 70 };
          announce AS4
 In this example, AS4's routes are announced to AS2 with the med
 attribute's value set to 5 and community 70 added to the community
 list.
 Example:
  aut-num: AS1
  export: to AS-FOO announce ANY
 In this example, AS1 announces all of its routes to the ASes in the
 set AS-FOO.

6.3 Other Routing Protocols, Multi-Protocol Routing Protocols, and

 Injecting Routes Between Protocols
 The more complete syntax of the import and export attributes are as
 follows:
  import: [protocol <protocol-1>] [into <protocol-2>]
          from <peering-1> [action <action-1>]
          . . .
          from <peering-N> [action <action-N>]
          accept <filter>
  export: [protocol <protocol-1>] [into <protocol-2>]
          to <peering-1> [action <action-1>]
          . . .
          to <peering-N> [action <action-N>]
          announce <filter>

Alaettinoglu, et al. Standards Track [Page 29] RFC 2622 RPSL June 1999

 Where the optional protocol specifications can be used for specifying
 policies for other routing protocols, or for injecting routes of one
 protocol into another protocol, or for multi-protocol routing
 policies.  The valid protocol names are defined in the dictionary.
 The <protocol-1> is the name of the protocol whose routes are being
 exchanged.  The <protocol-2> is the name of the protocol which is
 receiving these routes.  Both <protocol-1> and <protocol-2> default
 to the Internet Exterior Gateway Protocol, currently BGP.
 In the following example, all interAS routes are injected into RIP.

aut-num: AS1 import: from AS2 accept AS2 export: protocol BGP4 into RIP

       to AS1 announce ANY
 In the following example, AS1 accepts AS2's routes including any more
 specifics of AS2's routes, but does not inject these extra more
 specific routes into OSPF.

aut-num: AS1 import: from AS2 accept AS2^+ export: protocol BGP4 into OSPF

       to AS1 announce AS2
 In the following example, AS1 injects its static routes (routes which
 are members of the set AS1:RS-STATIC-ROUTES) to the interAS routing
 protocol and appends AS1 twice to their AS paths.

aut-num: AS1 import: protocol STATIC into BGP4

       from AS1 action aspath.prepend(AS1, AS1);
       accept AS1:RS-STATIC-ROUTES
 In the following example, AS1 imports different set of unicast routes
 for multicast reverse path forwarding from AS2:

aut-num: AS1 import: from AS2 accept AS2 import: protocol IDMR

       from AS2 accept AS2:RS-RPF-ROUTES

Alaettinoglu, et al. Standards Track [Page 30] RFC 2622 RPSL June 1999

6.4 Ambiguity Resolution

 It is possible that the same peering can be covered by more that one
 peering specification in a policy expression.  For example:

aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 2;

       from AS2 7.7.7.2 at 7.7.7.1 action pref = 1;
       accept AS4
 This is not an error, though definitely not desirable.  To break the
 ambiguity, the action corresponding to the first peering
 specification is used.  That is the routes are accepted with
 preference 2.  We call this rule as the specification-order rule.
 Consider the example:

aut-num: AS1 import: from AS2 action pref = 2;

       from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5;
       accept AS4
 where both peering specifications cover the peering 7.7.7.1-7.7.7.2,
 though the second one covers it more specifically.  The specification
 order rule still applies, and only the action "pref = 2" is executed.
 In fact, the second peering-action pair has no use since the first
 peering-action pair always covers it.  If the intended policy was to
 accept these routes with preference 1 on this particular peering and
 with preference 2 in all other peerings, the user should have
 specified:

aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5;

       from AS2                    action pref = 2;
       accept AS4
 It is also possible that more than one policy expression can cover
 the same set of routes for the same peering.  For example:

aut-num: AS1 import: from AS2 action pref = 2; accept AS4 import: from AS2 action pref = 1; accept AS4

 In this case, the specification-order rule is still used.  That is,
 AS4's routes are accepted from AS2 with preference 2.  If the filters
 were overlapping but not exactly the same:

Alaettinoglu, et al. Standards Track [Page 31] RFC 2622 RPSL June 1999

aut-num: AS1 import: from AS2 action pref = 2; accept AS4 import: from AS2 action pref = 1; accept AS4 OR AS5

 the AS4's routes are accepted from AS2 with preference 2 and however
 AS5's routes are also accepted, but with preference 1.
 We next give the general specification order rule for the benefit of
 the RPSL implementors.  Consider two policy expressions:

aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-2 action action-2 accept filter-2

 The above policy expressions are equivalent to the following three
 expressions where there is no ambiguity:

aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-3 action action-2 accept filter-2 AND NOT filter-1 import: from peerings-4 action action-2 accept filter-2

 where peerings-3 are those that are covered by both peerings-1 and
 peerings-2, and peerings-4 are those that are covered by peerings-2
 but not by peerings-1 ("filter-2 AND NOT filter-1" matches the routes
 that are matched by filter-2 but not by filter-1).
 Example:

aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1

       action pref = 2;
       accept {128.9.0.0/16}

import: from AS2

       action pref = 1;
       accept {128.9.0.0/16, 75.0.0.0/8}
 Lets consider two peerings with AS2, 7.7.7.1-7.7.7.2 and 9.9.9.1-
 9.9.9.2.  Both policy expressions cover 7.7.7.1-7.7.7.2.  On this
 peering, the route 128.9.0.0/16 is accepted with preference 2, and
 the route 75.0.0.0/8 is accepted with preference 1.  The peering
 9.9.9.1-9.9.9.2 is only covered by the second policy expressions.
 Hence, both the route 128.9.0.0/16 and the route 75.0.0.0/8 are
 accepted with preference 1 on peering 9.9.9.1-9.9.9.2.
 Note that the same ambiguity resolution rules also apply to export
 and default policy expressions.

Alaettinoglu, et al. Standards Track [Page 32] RFC 2622 RPSL June 1999

6.5 default Attribute: Default Policy Specification

 Default routing policies are specified using the default attribute.
 The default attribute has the following syntax:
  default: to <peering> [action <action>] [networks <filter>]
 The <action> and <filter> specifications are optional.  The semantics
 are as follows:  The <peering> specification indicates the AS (and
 the router if present) is being defaulted to; the <action>
 specification, if present, indicates various attributes of
 defaulting, for example a relative preference if multiple defaults
 are specified; and the <filter> specifications, if present, is a
 policy filter.  A router only uses the default policy if it received
 the routes matched by <filter> from this peer.
 In the following example, AS1 defaults to AS2 for routing.

aut-num: AS1 default: to AS2

 In the following example, router 7.7.7.1 in AS1 defaults to router
 7.7.7.2 in AS2.

aut-num: AS1 default: to AS2 7.7.7.2 at 7.7.7.1

 In the following example, AS1 defaults to AS2 and AS3, but prefers
 AS2 over AS3.

aut-num: AS1 default: to AS2 action pref = 1; default: to AS3 action pref = 2;

 In the following example, AS1 defaults to AS2 and uses 128.9.0.0/16
 as the default network.

aut-num: AS1 default: to AS2 networks { 128.9.0.0/16 }

6.6 Structured Policy Specification

 The import and export policies can be structured.  We only reccomend
 structured policies to advanced RPSL users.  Please feel free to skip
 this section.
 The syntax for a structured policy specification is the following:

Alaettinoglu, et al. Standards Track [Page 33] RFC 2622 RPSL June 1999

 <import-factor> ::= from <peering-1> [action <action-1>]
                     . . .
                     from <peering-N> [action <action-N>]
                     accept <filter>;
 <import-term> ::=  <import-factor> |
                    LEFT-BRACE
                    <import-factor>
                    . . .
                    <import-factor>
                    RIGHT-BRACE
 <import-expression> ::= <import-term>                            |
                         <import-term> EXCEPT <import-expression> |
                         <import-term> REFINE <import-expression>
 import: [protocol <protocol1>] [into <protocol2>]
         <import-expression>
 Please note the semicolon at the end of an <import-factor>.  If the
 policy specification is not structured (as in all the examples in
 other sections), this semicolon is optional.  The syntax and
 semantics for an <import-factor> is already defined in Section 6.1.
 An <import-term> is either a sequence of <import-factor>'s enclosed
 within matching braces (i.e. `{' and `}') or just a single <import-
 factor>.  The semantics of an <import-term> is the union of <import-
 factor>'s using the specification order rule.  An <import-expression>
 is either a single <import-term> or an <import-term> followed by one
 of the keywords "except" and "refine", followed by another <import-
 expression>.  Note that our definition allows nested expressions.
 Hence there can be exceptions to exceptions, refinements to
 refinements, or even refinements to exceptions, and so on.
 The semantics for the except operator is as follows: The result of an
 except operation is another <import-term>.  The resulting policy set
 contains the policies of the right hand side but their filters are
 modified to only include the routes also matched by the left hand
 side.  The policies of the left hand side are included afterwards and
 their filters are modified to exclude the routes matched by the right
 hand side.  Please note that the filters are modified during this
 process but the actions are copied verbatim.  When there are multiple
 levels of nesting, the operations (both except and refine) are
 performed right to left.

Alaettinoglu, et al. Standards Track [Page 34] RFC 2622 RPSL June 1999

 Consider the following example:

import: from AS1 action pref = 1; accept as-foo;

       except {
          from AS2 action pref = 2; accept AS226;
          except {
             from AS3 action pref = 3; accept {128.9.0.0/16};
          }
       }
 where the route 128.9.0.0/16 is originated by AS226, and AS226 is a
 member of the as set as-foo.  In this example, the route 128.9.0.0/16
 is accepted from AS3, any other route (not 128.9.0.0/16) originated
 by AS226 is accepted from AS2, and any other ASes' routes in as-foo
 is accepted from AS1.
 We can come to the same conclusion using the algebra defined above.
 Consider the inner exception specification:
 from AS2 action pref = 2; accept AS226;
 except {
    from AS3 action pref = 3; accept {128.9.0.0/16};
 }

is equivalent to

{
 from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16};
 from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16};
}

Hence, the original expression is equivalent to:

import: from AS1 action pref = 1; accept as-foo;

       except {
          from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16};
          from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16};
       }

which is equivalent to

import: {

Alaettinoglu, et al. Standards Track [Page 35] RFC 2622 RPSL June 1999

 from AS3 action pref = 3;
          accept as-foo AND AS226 AND {128.9.0.0/16};
 from AS2 action pref = 2;
          accept as-foo AND AS226 AND NOT {128.9.0.0/16};
 from AS1 action pref = 1;
          accept as-foo AND NOT
            (AS226 AND NOT {128.9.0.0/16} OR AS226 AND {128.9.0.0/16});
 }

Since AS226 is in as-foo and 128.9.0.0/16 is in AS226, it simplifies to:

import: {

        from AS3 action pref = 3; accept {128.9.0.0/16};
        from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16};
        from AS1 action pref = 1; accept as-foo AND NOT AS226;
      }
 In the case of the refine operator, the resulting set is constructed
 by taking the cartasian product of the two sides as follows:  for
 each policy l in the left hand side and for each policy r in the
 right hand side, the peerings of the resulting policy are the
 peerings common to both r and l; the filter of the resulting policy
 is the intersection of l's filter and r's filter; and action of the
 resulting policy is l's action followed by r's action.  If there are
 no common peerings, or if the intersection of filters is empty, a
 resulting policy is not generated.
 Consider the following example:

import: { from AS-ANY action pref = 1; accept community(3560:10);

         from AS-ANY action pref = 2; accept community(3560:20);
       } refine {
          from AS1 accept AS1;
          from AS2 accept AS2;
          from AS3 accept AS3;
       }
 Here, any route with community 3560:10 is assigned a preference of 1
 and any route with community 3560:20 is assigned a preference of 2
 regardless of whom they are imported from.  However, only AS1's
 routes are imported from AS1, and only AS2's routes are imported from
 AS2, and only AS3's routes are imported form AS3, and no routes are
 imported from any other AS. We can reach the same conclusion using
 the above algebra.  That is, our example is equivalent to:

Alaettinoglu, et al. Standards Track [Page 36] RFC 2622 RPSL June 1999

import: {

 from AS1 action pref = 1; accept community(3560:10) AND AS1;
 from AS1 action pref = 2; accept community(3560:20) AND AS1;
 from AS2 action pref = 1; accept community(3560:10) AND AS2;
 from AS2 action pref = 2; accept community(3560:20) AND AS2;
 from AS3 action pref = 1; accept community(3560:10) AND AS3;
 from AS3 action pref = 2; accept community(3560:20) AND AS3;

}

 Note that the common peerings between "from AS1" and "from AS-ANY"
 are those peerings in "from AS1".  Even though we do not formally
 define "common peerings", it is straight forward to deduce the
 definition from the definitions of peerings (please see Section 5.6).
 Consider the following example:

import: {

 from AS-ANY action med = 0; accept {0.0.0.0/0^0-18};
 } refine {
      from AS1 at 7.7.7.1 action pref = 1; accept AS1;
      from AS1            action pref = 2; accept AS1;
   }
 where only routes of length 0 to 18 are accepted and med's value is
 set to 0 to disable med's effect for all peerings; In addition, from
 AS1 only AS1's routes are imported, and AS1's routes imported at
 7.7.7.1 are preferred over other peerings.  This is equivalent to:

import: {

    from AS1 at 7.7.7.1 action med=0; pref=1; accept {0.0.0.0/0^0-

18} AND AS1;

  from  AS1             action med=0; pref=2; accept {0.0.0.0/0^0-

18} AND AS1; }

 The above syntax and semantics also apply equally to structured
 export policies with "from" replaced with "to" and "accept" is
 replaced with "announce".

7 dictionary Class

 The dictionary class provides extensibility to RPSL. Dictionary
 objects define routing policy attributes, types, and routing
 protocols.  Routing policy attributes, henceforth called rp-
 attributes, may correspond to actual protocol attributes, such as the
 BGP path attributes (e.g. community, dpa, and AS-path), or they may
 correspond to router features (e.g. BGP route flap damping).  As new
 protocols, new protocol attributes, or new router features are

Alaettinoglu, et al. Standards Track [Page 37] RFC 2622 RPSL June 1999

 introduced, the dictionary object is updated to include appropriate
 rp-attribute and protocol definitions.
 An rp-attribute is an abstract class; that is a data representation
 is not available.  Instead, they are accessed through access methods.
 For example, the rp-attribute for the BGP AS-path attribute is called
 aspath; and it has an access method called prepend which stuffs extra
 AS numbers to the AS-path attributes.  Access methods can take
 arguments.  Arguments are strongly typed.  For example, the method
 prepend above takes AS numbers as arguments.
 Once an rp-attribute is defined in the dictionary, it can be used to
 describe policy filters and actions.  Policy analysis tools are
 required to fetch the dictionary object and recognize newly defined
 rp-attributes, types, and protocols.  The analysis tools may
 approximate policy analyses on rp-attributes that they do not
 understand:  a filter method may always match, and an action method
 may always perform no-operation.  Analysis tools may even download
 code to perform appropriate operations using mechanisms outside the
 scope of RPSL.
 We next describe the syntax and semantics of the dictionary class.
 This description is not essential for understanding dictionary
 objects (but it is essential for creating one).  Please feel free to
 skip to the RPSL Initial Dictionary subsection (Section 7.1).
 The attributes of the dictionary class are shown in Figure 24.  The
 dictionary attribute is the name of the dictionary object, obeying
 the RPSL naming rules.  There can be many dictionary objects, however
 there is always one well-known dictionary object "RPSL". All tools
 use this dictionary by default.

Attribute Value Type dictionary <object-name> mandatory, single-valued,

                                     class key

rp-attribute see description in text optional, multi valued typedef see description in text optional, multi valued protocol see description in text optional, multi valued

                Figure 24:  dictionary Class Attributes
 The rp-attribute attribute has the following syntax:
 rp-attribute: <name>
    <method-1>(<type-1-1>, ..., <type-1-N1> [, "..."])
    ...
    <method-M>(<type-M-1>, ..., <type-M-NM> [, "..."])

Alaettinoglu, et al. Standards Track [Page 38] RFC 2622 RPSL June 1999

 where <name> is the name of the rp-attribute; and <method-i> is the
 name of an access method for the rp-attribute, taking Ni arguments
 where the j-th argument is of type <type-i-j>.  A method name is
 either an RPSL name or one of the operators defined in Figure 25.
 The operator methods with the exception of operator() and operator[]
 can take only one argument.
 operator=           operator==
 operator<<=         operator<
 operator>>=         operator>
 operator+=          operator>=
 operator-=          operator<=
 operator*=          operator!=
 operator/=          operator()
 operator.=          operator[]
                         Figure 25:  Operators
 An rp-attribute can have many methods defined for it.  Some of the
 methods may even have the same name, in which case their arguments
 are of different types.  If the argument list is followed by "...",
 the method takes a variable number of arguments.  In this case, the
 actual arguments after the Nth argument are of type <type-N>.
 Arguments are strongly typed.  A <type> in RPSL is either a
 predefined type, a union type, a list type, or a dictionary defined
 type.  The predefined types are listed in Figure 26.
 integer[lower, upper]              ipv4_address
 real[lower, upper]                 address_prefix
 enum[name, name, ...]              address_prefix_range
 string                             dns_name
 boolean                            filter
 rpsl_word                          as_set_name
 free_text                          route_set_name
 email                              rtr_set_name
 as_number                          filter_set_name
                                    peering_set_name
                      Figure 26:  Predefined Types
 The integer and the real predefined types can be followed by a lower
 and an upper bound to specify the set of valid values of the
 argument.  The range specification is optional.  We use the ANSI C
 language conventions for representing integer, real and string
 values.  The enum type is followed by a list of RPSL names which are

Alaettinoglu, et al. Standards Track [Page 39] RFC 2622 RPSL June 1999

 the valid values of the type.  The boolean type can take the values
 true or false.  as_number, ipv4_address, address_prefix and dns_name
 types are as in Section 2.  filter type is a policy filter as in
 Section 6.  The value of filter type is suggested to be enclosed in
 parenthesis.
 The syntax of a union type is as follows:
  union <type-1>, ... , <type-N>
 where <type-i> is an RPSL type.  The union type is either of the
 types <type-1> through <type-N> (analogous to unions in C[14]).
 The syntax of a list type is as follows:
 list [<min_elems>:<max_elems>] of <type>
 In this case, the list elements are of <type> and the list contains
 at least <min_elems> and at most <max_elems> elements.  The size
 specification is optional.  If it is not specified, there is no
 restriction in the number of list elements.  A value of a list type
 is represented as a sequence of elements separated by the character
 "," and enclosed by the characters "{" and "}".
 The typedef attribute in the dictionary defines named types as
 follows:
 typedef: <name> <type>
 where <name> is a name for type <type>.  typedef attribute is
 paticularly useful when the type defined is not a predefined type
 (e.g. list of unions, list of lists, etc.).
 A protocol attribute of the dictionary class defines a protocol and a
 set of peering parameters for that protocol (which are used in inet-
 rtr class in Section 9).  Its syntax is as follows:
 protocol: <name>
  MANDATORY | OPTIONAL <parameter-1>(<type-1-1>,...,
                       <type-1-N1> [,"..."])
    ...
  MANDATORY | OPTIONAL <parameter-M>(<type-M-1>,...,
                       <type-M-NM> [,"..."])
 where <name> is the name of the protocol; MANDATORY and OPTIONAL are
 keywords; and <parameter-i> is a peering parameter for this protocol,
 taking Ni many arguments.  The syntax and semantics of the arguments
 are as in the rp-attribute.  If the keyword MANDATORY is used, the

Alaettinoglu, et al. Standards Track [Page 40] RFC 2622 RPSL June 1999

 parameter is mandatory and needs to be specified for each peering of
 this protocol.  If the keyword OPTIONAL is used, the parameter can be
 skipped.

7.1 Initial RPSL Dictionary and Example Policy Actions and Filters

dictionary: RPSL rp-attribute: # preference, smaller values represent higher preferences

            pref
            operator=(integer[0, 65535])

rp-attribute: # BGP multi_exit_discriminator attribute

            med
            # to set med to 10: med = 10;
            # to set med to the IGP metric: med = igp_cost;
            operator=(union integer[0, 65535], enum[igp_cost])

rp-attribute: # BGP destination preference attribute (dpa)

            dpa
            operator=(integer[0, 65535])

rp-attribute: # BGP aspath attribute

            aspath
            # prepends AS numbers from last to first order
            prepend(as_number, ...)

typedef: # a community value in RPSL is either

            #  - a 4 byte integer (ok to use 3561:70 notation)
            #  - internet, no_export, no_advertise (see RFC-1997)
            community_elm union
                integer[1, 4294967295],
                enum[internet, no_export, no_advertise],

typedef: # list of community values { 40, no_export, 3561:70 }

            community_list list of community_elm

rp-attribute: # BGP community attribute

            community
            # set to a list of communities
            operator=(community_list)
            # append community values
            operator.=(community_list)
            append(community_elm, ...)
            # delete community values
            delete(community_elm, ...)
            # a filter: true if one of community values is contained
            contains(community_elm, ...)
            # shortcut to contains: community(no_export, 3561:70)
            operator()(community_elm, ...)
            # order independent equality comparison
            operator==(community_list)

rp-attribute: # next hop router in a static route

            next-hop
            # to set to 7.7.7.7: next-hop = 7.7.7.7;

Alaettinoglu, et al. Standards Track [Page 41] RFC 2622 RPSL June 1999

            # to set to router's own address: next-hop = self;
            operator=(union ipv4_address, enum[self])

rp-attribute: # cost of a static route

            cost
            operator=(integer[0, 65535])

protocol: BGP4

        # as number of the peer router
        MANDATORY asno(as_number)
        # enable flap damping
        OPTIONAL flap_damp()
        OPTIONAL flap_damp(integer[0,65535],
                           # penalty per flap
                           integer[0,65535],
                           # penalty value for supression
                           integer[0,65535],
                           # penalty value for reuse
                           integer[0,65535],
                           # halflife in secs when up
                           integer[0,65535],
                           # halflife in secs when down
                           integer[0,65535])
                           # maximum penalty

protocol: OSPF protocol: RIP protocol: IGRP protocol: IS-IS protocol: STATIC protocol: RIPng protocol: DVMRP protocol: PIM-DM protocol: PIM-SM protocol: CBT protocol: MOSPF

                      Figure 27:  RPSL Dictionary
 Figure 27 shows the initial RPSL dictionary.  It has seven rp-
 attributes:  pref to assign local preference to the routes accepted;
 med to assign a value to the MULTI_EXIT_DISCRIMINATOR BGP attribute;
 dpa to assign a value to the DPA BGP attribute; aspath to prepend a
 value to the AS_PATH BGP attribute; community to assign a value to or
 to check the value of the community BGP attribute; next-hop to assign
 next hop routers to static routes; and cost to assign a cost to
 static routes.  The dictionary defines two types:  community_elm and
 community_list.  community_elm type is either a 4-byte unsigned
 integer, or one of the keywords internet, no_export or no_advertise
 (defined in [9]).  An integer can be specified using two 2-byte

Alaettinoglu, et al. Standards Track [Page 42] RFC 2622 RPSL June 1999

 integers seperated by ":"  to partition the community number space so
 that a provider can use its AS number as the first two bytes, and
 assigns a semantics of its choice to the last two bytes.
 The initial dictionary (Figure 27) defines only options for the
 Border Gateway Protocol:  asno and flap_damp.  The mandatory asno
 option is the AS number of the peer router.  The optional flap_damp
 option instructs the router to damp route flaps [21] when importing
 routes from the peer router.
 It can be specified with or without parameters.  If parameters are
 missing, they default to:
 flap_damp(1000, 2000, 750, 900, 900, 20000)
 That is, a penalty of 1000 is assigned at each route flap, the route
 is suppressed when penalty reaches 2000.  The penalty is reduced in
 half after 15 minutes (900 seconds) of stability regardless of
 whether the route is up or down.  A supressed route is reused when
 the penalty falls below 750.  The maximum penalty a route can be
 assigned is 20,000 (i.e. the maximum suppress time after a route
 becomes stable is about 75 minutes).  These parameters are consistent
 with the default flap damping parameters in several routers.

Policy Actions and Filters Using RP-Attributes

 The syntax of a policy action or a filter using an rp-attribute x is
 as follows:
  x.method(arguments)
  x "op" argument
 where method is a method and "op" is an operator method of the rp-
 attribute x.  If an operator method is used in specifying a composite
 policy filter, it evaluates earlier than the composite policy filter
 operators (i.e. AND, OR, NOT, and implicit or operator).
 The pref rp-attribute can be assigned a positive integer as follows:
 pref = 10;
 The med rp-attribute can be assigned either a positive integer or the
 word "igp_cost" as follows:
 med = 0;
 med = igp_cost;
 The dpa rp-attribute can be assigned a positive integer as follows:

Alaettinoglu, et al. Standards Track [Page 43] RFC 2622 RPSL June 1999

 dpa = 100;
 The BGP community attribute is list-valued, that is it is a list of
 4-byte integers each representing a "community".  The following
 examples demonstrate how to add communities to this rp-attribute:
 community .= { 100 };
 community .= { NO_EXPORT };
 community .= { 3561:10 };
 In the last case, a 4-byte integer is constructed where the more
 significant two bytes equal 3561 and the less significant two bytes
 equal 10.  The following examples demonstrate how to delete
 communities from the community rp-attribute:
 community.delete(100, NO_EXPORT, 3561:10);
 Filters that use the community rp-attribute can be defined as
 demonstrated by the following examples:
 community.contains(100, NO_EXPORT, 3561:10);
 community(100, NO_EXPORT, 3561:10);             # shortcut
 The community rp-attribute can be set to a list of communities as
 follows:
 community = {100, NO_EXPORT, 3561:10, 200};
 community = {};
 In this first case, the community rp-attribute contains the
 communities 100, NO_EXPORT, 3561:10, and 200.  In the latter case,
 the community rp-attribute is cleared.  The community rp-attribute
 can be compared against a list of communities as follows:
 community == {100, NO_EXPORT, 3561:10, 200};   # exact match
 To influence the route selection, the BGP as_path rp-attribute can be
 made longer by prepending AS numbers to it as follows:
 aspath.prepend(AS1);
 aspath.prepend(AS1, AS1, AS1);
 The following examples are invalid:
 med = -50;                     # -50 is not in the range
 med = igp;                     # igp is not one of the enum values
 med.assign(10);                # method assign is not defined
 community.append(AS3561:20);   # the first argument should be 3561

Alaettinoglu, et al. Standards Track [Page 44] RFC 2622 RPSL June 1999

 Figure 28 shows a more advanced example using the rp-attribute
 community.  In this example, AS3561 bases its route selection
 preference on the community attribute.  Other ASes may indirectly
 affect AS3561's route selection by including the appropriate
 communities in their route announcements.
  aut-num: AS1
  export: to AS2 action community.={3561:90};
          to AS3 action community.={3561:80};
          announce AS1
  as-set: AS3561:AS-PEERS
  members: AS2, AS3
  aut-num: AS3561
  import: from AS3561:AS-PEERS
          action pref = 10;
          accept community(3561:90)
  import: from AS3561:AS-PEERS
          action pref = 20;
          accept community(3561:80)
  import: from AS3561:AS-PEERS
          action pref = 20;
          accept community(3561:70)
  import: from AS3561:AS-PEERS
          action pref = 0;
          accept ANY
         Figure 28:  Policy example using the community rp-attribute.

8 Advanced route Class

8.1 Specifying Aggregate Routes

 The components, aggr-bndry, aggr-mtd, export-comps, inject, and holes
 attributes are used for specifying aggregate routes [11].  A route
 object specifies an aggregate route if any of these attributes, with
 the exception of inject, is specified.  The origin attribute for an
 aggregate route is the AS performing the aggregation, i.e. the
 aggregator AS. In this section, we used the term "aggregate" to refer
 to the route generated, the term "component" to refer to the routes
 used to generate the path attributes of the aggregate, and the term
 "more specifics" to refer to any route which is a more specific of
 the aggregate regardless of whether it was used to form the path
 attributes.

Alaettinoglu, et al. Standards Track [Page 45] RFC 2622 RPSL June 1999

 The components attribute defines what component routes are used to
 form the aggregate.  Its syntax is as follows:
 components: [ATOMIC] [[<filter>] [protocol <protocol> <filter> ...]]
 where <protocol> is a routing protocol name such as BGP4, OSPF or RIP
 (valid names are defined in the dictionary) and <filter> is a policy
 expression.  The routes that match one of these filters and are
 learned from the corresponding protocol are used to form the
 aggregate.  If <protocol> is omitted, it defaults to any protocol.
 <filter> implicitly contains an "AND" term with the more specifics of
 the aggregate so that only the component routes are selected.  If the
 keyword ATOMIC is used, the aggregation is done atomically [11].  If
 a <filter> is not specified it defaults to more specifics.  If the
 components attribute is missing, all more specifics without the
 ATOMIC keyword is used.
 route: 128.8.0.0/15
 origin: AS1
 components: <^AS2>
 route: 128.8.0.0/15
 origin: AS1
 components: protocol BGP4 {128.8.0.0/16^+}
             protocol OSPF {128.9.0.0/16^+}
                Figure 29:  Two aggregate route objects.
 Figure 29 shows two route objects.  In the first example, more
 specifics of 128.8.0.0/15 with AS paths starting with AS2 are
 aggregated.  In the second example, some routes learned from BGP and
 some routes learned form OSPF are aggregated.
 The aggr-bndry attribute is an AS expression over AS numbers and sets
 (see Section 5.6).  The result defines the set of ASes which form the
 aggregation boundary.  If the aggr-bndry attribute is missing, the
 origin AS is the sole aggregation boundary.  Outside the aggregation
 boundary, only the aggregate is exported and more specifics are
 suppressed.  However, within the boundary, the more specifics are
 also exchanged.
 The aggr-mtd attribute specifies how the aggregate is generated.  Its
 syntax is as follows:
aggr-mtd: inbound
        | outbound [<as-expression>]

Alaettinoglu, et al. Standards Track [Page 46] RFC 2622 RPSL June 1999

 where <as-expression> is an expression over AS numbers and sets (see
 Section 5.6).  If <as-expression> is missing, it defaults to AS-ANY.
 If outbound aggregation is specified, the more specifics of the
 aggregate will be present within the AS and the aggregate will be
 formed at all inter-AS boundaries with ASes in <as-expression> before
 export, except for ASes that are within the aggregating boundary
 (i.e. aggr-bndry is enforced regardless of <as-expression>).  If
 inbound aggregation is specified, the aggregate is formed at all
 inter-AS boundaries prior to importing routes into the aggregator AS.
 Note that <as-expression> can not be specified with inbound
 aggregation.  If aggr-mtd attribute is missing, it defaults to
 "outbound AS-ANY".
 route:      128.8.0.0/15            route:      128.8.0.0/15
 origin:     AS1                     origin:     AS2
 components: {128.8.0.0/15^-}        components: {128.8.0.0/15^-}
 aggr-bndry: AS1 OR AS2              aggr-bndry: AS1 OR AS2
 aggr-mtd:   outbound AS-ANY         aggr-mtd:   outbound AS-ANY
           Figure 30:  Outbound multi-AS aggregation example.
 Figure 30 shows an example of an outbound aggregation.  In this
 example, AS1 and AS2 are coordinating aggregation and announcing only
 the less specific 128.8.0.0/15 to outside world, but exchanging more
 specifics between each other.  This form of aggregation is useful
 when some of the components are within AS1 and some are within AS2.
 When a set of routes are aggregated, the intent is to export only the
 aggregate route and suppress exporting of the more specifics outside
 the aggregation boundary.  However, to satisfy certain policy and
 topology constraints (e.g. a multi-homed component), it is often
 required to export some of the components.  The export-comps
 attribute equals an RPSL filter that matches the more specifics that
 need to be exported outside the aggregation boundary.  If this
 attribute is missing, more specifics are not exported outside the
 aggregation boundary.  Note that, the export-comps filter contains an
 implicit "AND" term with the more specifics of the aggregate.
 Figure 31 shows an example of an outbound aggregation.  In this
 example, the more specific 128.8.8.0/24 is exported outside AS1 in
 addition to the aggregate.  This is useful, when 128.8.8.0/24 is
 multi-homed site to AS1 with some other AS.

Alaettinoglu, et al. Standards Track [Page 47] RFC 2622 RPSL June 1999

    route:      128.8.0.0/15
    origin:     AS1
    components: {128.8.0.0/15^-}
    aggr-mtd:   outbound AS-ANY
    export-comps: {128.8.8.0/24}
           Figure 31:  Outbound aggregation with export exception.
 The inject attribute specifies which routers perform the aggregation
 and when they perform it.  Its syntax is as follow:
inject: [at <router-expression>] ...
        [action <action>]
        [upon <condition>]
 where <action> is an action specification (see Section 6.1.1),
 <condition> is a boolean expression described below, and <router-
 expression> is as described in Section 5.6.
 All routers in <router-expression> and in the aggregator AS perform
 the aggregation.  If a <router-expression> is not specified, all
 routers inside the aggregator AS perform the aggregation.  The
 <action> specification may set path attributes of the aggregate, such
 as assign a preferences to the aggregate.
 The upon clause is a boolean condition.  The aggregate is generated
 if and only if this condition is true.  <condition> is a boolean
 expression using the logical operators AND and OR (i.e. operator NOT
 is not allowed) over:
 HAVE-COMPONENTS { list of prefixes }
 EXCLUDE { list of prefixes }
 STATIC
 The list of prefixes in HAVE-COMPONENTS can only be more specifics of
 the aggregate.  It evaluates to true when all the prefixes listed are
 present in the routing table of the aggregating router.  The list can
 also include prefix ranges (i.e. using operators ^-, ^+, ^n, and ^n-
 m).  In this case, at least one prefix from each prefix range needs
 to be present in the routing table for the condition to be true.  The
 list of prefixes in EXCLUDE can be arbitrary.  It evaluates to true
 when none of the prefixes listed is present in the routing table.
 The list can also include prefix ranges, and no prefix in that range
 should be present in the routing table.  The keyword static always
 evaluates to true.  If no upon clause is specified the aggregate is
 generated if an only if there is a component in the routing table
 (i.e. a more specific that matches the filter in the components

Alaettinoglu, et al. Standards Track [Page 48] RFC 2622 RPSL June 1999

 attribute).
 route:      128.8.0.0/15
 origin:     AS1
 components: {128.8.0.0/15^-}
 aggr-mtd:   outbound AS-ANY
 inject:     at 1.1.1.1 action dpa = 100;
 inject:     at 1.1.1.2 action dpa = 110;
 route:      128.8.0.0/15
 origin:     AS1
 components: {128.8.0.0/15^-}
 aggr-mtd:   outbound AS-ANY
 inject:     upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16}
 holes:      128.8.8.0/24
                    Figure 32:  Examples of inject.
 Figure 32 shows two examples.  In the first case, the aggregate is
 injected at two routers each one setting the dpa path attribute
 differently.  In the second case, the aggregate is generated only if
 both 128.8.0.0/16 and 128.9.0.0/16 are present in the routing table,
 as opposed to the first case where the presence of just one of them
 is sufficient for injection.
 The holes attribute lists the component address prefixes which are
 not reachable through the aggregate route (perhaps that part of the
 address space is unallocated).  The holes attribute is useful for
 diagnosis purposes.  In Figure 32, the second example has a hole,
 namely 128.8.8.0/24.  This may be due to a customer changing
 providers and taking this part of the address space with it.

8.1.1 Interaction with policies in aut-num class

 An aggregate formed is announced to other ASes only if the export
 policies of the AS allows exporting the aggregate.  When the
 aggregate is formed, the more specifics are suppressed from being
 exported except to the ASes in aggr-bndry and except the components
 in export-comps.  For such exceptions to happen, the export policies
 of the AS should explicitly allow exporting of these exceptions.
 If an aggregate is not formed (due to the upon clause), then the more
 specifics of the aggregate can be exported to other ASes, but only if
 the export policies of the AS allows it.  In other words, before a
 route (aggregate or more specific) is exported it is filtered twice,
 once based on the route objects, and once based on the export
 policies of the AS.

Alaettinoglu, et al. Standards Track [Page 49] RFC 2622 RPSL June 1999

 route:        128.8.0.0/16
 origin:       AS1
 route:        128.9.0.0/16
 origin:       AS1
 route:        128.8.0.0/15
 origin:       AS1
 aggr-bndry:   AS1 or AS2 or AS3
 aggr-mtd:     outbound AS3 or AS4 or AS5
 components:   {128.8.0.0/16, 128.9.0.0/16}
 inject:       upon HAVE-COMPONENTS {128.9.0.0/16, 128.8.0.0/16}
 aut-num: AS1
 export:  to AS2 announce AS1
 export:  to AS3 announce AS1 and not {128.9.0.0/16}
 export:  to AS4 announce AS1
 export:  to AS5 announce AS1
 export:  to AS6 announce AS1
        Figure 33:  Interaction with policies in aut-num class.
 In Figure 33 shows an interaction example.  By examining the route
 objects, the more specifics 128.8.0.0/16 and 128.9.0.0/16 should be
 exchanged between AS1, AS2 and AS3 (i.e. the aggregation boundary).
 Outbound aggregation is done to AS4 and AS5 and not to AS3, since AS3
 is in the aggregation boundary.  The aut-num object allows exporting
 both components to AS2, but only the component 128.8.0.0/16 to AS3.
 The aggregate can only be formed if both components are available.
 In this case, only the aggregate is announced to AS4 and AS5.
 However, if one of the components is not available the aggregate will
 not be formed, and any available component or more specific will be
 exported to AS4 and AS5.  Regardless of aggregation is performed or
 not, only the more specifics will be exported to AS6 (it is not
 listed in the aggr-mtd attribute).
 When doing an inbound aggregation, configuration generators may
 eliminating the aggregation statements on routers where import policy
 of the AS prohibits importing of any more specifics.

8.1.2 Ambiguity resolution with overlapping aggregates

 When several aggregate routes are specified and they overlap, i.e.
 one is less specific of the other, they must be evaluated more
 specific to less specific order.  When an outbound aggregation is
 performed for a peer, the aggregate and the components listed in the
 export-comps attribute for that peer are available for generating the

Alaettinoglu, et al. Standards Track [Page 50] RFC 2622 RPSL June 1999

 next less specific aggregate.  The components that are not specified
 in the export-comps attribute are not available.  A route is
 exportable to an AS if it is the least specific aggregate exportable
 to that AS or it is listed in the export-comps attribute of an
 exportable route.  Note that this is a recursive definition.
 route:        128.8.0.0/15
 origin:       AS1
 aggr-bndry:   AS1 or AS2
 aggr-mtd:     outbound
 inject:       upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16}
 route:        128.10.0.0/15
 origin:       AS1
 aggr-bndry:   AS1 or AS3
 aggr-mtd:     outbound
 inject:       upon HAVE-COMPONENTS {128.10.0.0/16, 128.11.0.0/16}
 export-comps: {128.11.0.0/16}
 route:        128.8.0.0/14
 origin:       AS1
 aggr-bndry:   AS1 or AS2 or AS3
 aggr-mtd:     outbound
 inject:       upon HAVE-COMPONENTS {128.8.0.0/15, 128.10.0.0/15}
 export-comps: {128.10.0.0/15}
                 Figure 34:  Overlapping aggregations.
 In Figure 34, AS1 together with AS2 aggregates 128.8.0.0/16 and
 128.9.0.0/16 into 128.8.0.0/15.  Together with AS3, AS1 aggregates
 128.10.0.0/16 and 128.11.0.0/16 into 128.10.0.0/15.  But altogether
 they aggregate these four routes into 128.8.0.0/14.  Assuming all
 four components are available, a router in AS1 for an outside AS, say
 AS4, will first generate 128.8.0.0/15 and 128.10.0.0/15.  This will
 make 128.8.0.0/15, 128.10.0.0/15 and its exception 128.11.0.0/16
 available for generating 128.8.0.0/14.  The router will then generate
 128.8.0.0/14 from these three routes.  Hence for AS4, 128.8.0.0/14
 and its exception 128.10.0.0/15 and its exception 128.11.0.0/16 will
 be exportable.
 For AS2, a router in AS1 will only generate 128.10.0.0/15.  Hence,
 128.10.0.0/15 and its exception 128.11.0.0/16 will be exportable.
 Note that 128.8.0.0/16 and 128.9.0.0/16 are also exportable since
 they did not participate in an aggregate exportable to AS2.

Alaettinoglu, et al. Standards Track [Page 51] RFC 2622 RPSL June 1999

 Similarly, for AS3, a router in AS1 will only generate 128.8.0.0/15.
 In this case 128.8.0.0/15, 128.10.0.0/16, 128.11.0.0/16 are
 exportable.

8.2 Specifying Static Routes

 The inject attribute can be used to specify static routes by using
 "upon static" as the condition:
inject: [at <router-expression>] ...
        [action <action>]
        upon static
 In this case, the routers in <router-expression> executes the
 <action> and injects the route to the interAS routing system
 statically.  <action> may set certain route attributes such as a
 next-hop router or a cost.
 In the following example, the router 7.7.7.1 injects the route
 128.7.0.0/16.  The next-hop routers (in this example, there are two
 next-hop routers) for this route are 7.7.7.2 and 7.7.7.3 and the
 route has a cost of 10 over 7.7.7.2 and 20 over 7.7.7.3.
 route:  128.7.0.0/16
 origin: AS1
 inject: at 7.7.7.1 action next-hop = 7.7.7.2; cost = 10; upon static
 inject: at 7.7.7.1 action next-hop = 7.7.7.3; cost = 20; upon static

9 inet-rtr Class

Routers are specified using the inet-rtr class. The attributes of the inet-rtr class are shown in Figure 35. The inet-rtr attribute is a valid DNS name of the router described. Each alias attribute, if present, is a canonical DNS name for the router. The local-as attribute specifies the AS number of the AS which owns/operates this router.

Attribute  Value                    Type
inet-rtr   <dns-name>               mandatory, single-valued, class key
alias      <dns-name>               optional, multi-valued
local-as   <as-number>              mandatory, single-valued
ifaddr     see description in text  mandatory, multi-valued
peer       see description in text  optional, multi-valued
member-of  list of <rtr-set-names>  optional, multi-valued
                 Figure 35:  inet-rtr Class Attributes

Alaettinoglu, et al. Standards Track [Page 52] RFC 2622 RPSL June 1999

 The value of an ifaddr attribute has the following syntax:
 <ipv4-address> masklen <integer> [action <action>]
 The IP address and the mask length are mandatory for each interface.
 Optionally an action can be specified to set other parameters of this
 interface.
 Figure 36 presents an example inet-rtr object.  The name of the
 router is "amsterdam.ripe.net".  "amsterdam1.ripe.net" is a canonical
 name for the router.  The router is connected to 4 networks.  Its IP
 addresses and mask lengths in those networks are specified in the
 ifaddr attributes.
  inet-rtr: Amsterdam.ripe.net
  alias:    amsterdam1.ripe.net
  local-as: AS3333
  ifaddr:   192.87.45.190 masklen 24
  ifaddr:   192.87.4.28   masklen 24
  ifaddr:   193.0.0.222   masklen 27
  ifaddr:   193.0.0.158   masklen 27
  peer:     BGP4 192.87.45.195 asno(AS3334), flap_damp()
                         Figure 36:  inet-rtr Objects
 Each peer attribute, if present, specifies a protocol peering with
 another router.  The value of a peer attribute has the following
 syntax:
   <protocol> <ipv4-address>      <options>
 | <protocol> <inet-rtr-name>     <options>
 | <protocol> <rtr-set-name>      <options>
 | <protocol> <peering-set-name>  <options>
 where <protocol> is a protocol name, <ipv4-address> is the IP address
 of the peer router, and <options> is a comma separated list of
 peering options for <protocol>.  Instead of the peer's IP address,
 its inet-rtr-name can be used.  Possible protocol names and
 attributes are defined in the dictionary (please see Section 7).  In
 the above example, the router has a BGP peering with the router
 192.87.45.195 in AS3334 and turns the flap damping on when importing
 routes from this router.
 Instead of a single peer, a group of peers can be specified by using
 the <rtr-set-name> and <peering-set-name> forms.  If <peering-set-
 name> form is being used only the peerings in the corresponding
 peering set that are with this router are included.  Figure 37 shows

Alaettinoglu, et al. Standards Track [Page 53] RFC 2622 RPSL June 1999

 an example inet-rtr object with peering groups.
  rtr-set: rtrs-ibgp-peers
  members: 1.1.1.1, 2.2.2.2, 3.3.3.3
  peering-set: prng-ebgp-peers
  peering: AS3334 192.87.45.195
  peering: AS3335 192.87.45.196
  inet-rtr: Amsterdam.ripe.net
  alias:    amsterdam1.ripe.net
  local-as: AS3333
  ifaddr:   192.87.45.190 masklen 24
  ifaddr:   192.87.4.28   masklen 24
  ifaddr:   193.0.0.222   masklen 27
  ifaddr:   193.0.0.158   masklen 27
  peer:     BGP4 rtrs-ibgp-peers asno(AS3333), flap_damp()
  peer:     BGP4 prng-ebgp-peers asno(PeerAS), flap_damp()
               Figure 37:  inet-rtr Object with peering groups

10 Extending RPSL

 Our experience with earlier routing policy languages and data formats
 (PRDB [2], RIPE-81 [8], and RIPE-181 [7]) taught us that RPSL had to
 be extensible.  As a result, extensibility was a primary design goal
 for RPSL.  New routing protocols or new features to existing routing
 protocols can be easily handled using RPSL's dictionary class.  New
 classes or new attributes to the existing classes can also be added.
 This section provides guidelines for extending RPSL. These guidelines
 are designed with an eye toward maintaining backward compatibility
 with existing tools and databases.  We next list the available
 options for extending RPSL from the most preferred to the least
 preferred order.

10.1 Extensions by changing the dictionary class

 The dictionary class is the primary mechanism provided to extend
 RPSL.  Dictionary objects define routing policy attributes, types,
 and routing protocols.
 We recommend updating the RPSL dictionary to include appropriate rp-
 attribute and protocol definitions as new path attributes or router
 features are introduced.  For example, in an earlier version of the
 RPSL document, it was only possible to specify that a router performs
 route flap damping on a peer, but it was not possible to specify the

Alaettinoglu, et al. Standards Track [Page 54] RFC 2622 RPSL June 1999

 parameters of route flap damping.  Later the parameters were added by
 changing the dictionary.
 When changing the dictionary, full compatibility should be
 maintained.  For example, in our flap damping case, we made the
 parameter specification optional in case this level of detail was not
 desired by some ISPs.  This also achieved compatibility.  Any object
 registered without the parameters will continue to be valid.  Any
 tool based on RPSL is expected to do a default action on routing
 policy attributes that they do not understand (e.g. issue a warning
 and otherwise ignore).  Hence, old tools upon encountering a flap
 damping specification with parameters will ignore the parameters.

10.2 Extensions by adding new attributes to existing classes

 New attributes can be added to any class.  To ensure full
 compatibility, new attributes should not contradict the semantics of
 the objects they are attached to.  Any tool that uses the IRR should
 be designed so that it ignores attributes that it doesn't understand.
 Most existing tools adhere to this design principle.
 We recommend adding new attributes to existing classes when a new
 aspect of a class is discovered.  For example, RPSL route class
 extends its RIPE-181 predecessor by including several new attributes
 that enable aggregate and static route specification.

10.3 Extensions by adding new classes

 New classes can be added to RPSL to store new types of policy data.
 Providing full compatibility is straight forward as long as existing
 classes are still understood.  Since a tool should only query the IRR
 for the classes that it understand, full compatibility should not be
 a problem in this case.
 Before adding a new class, one should question if the information
 contained in the objects of the new class could have better belonged
 to some other class.  For example, if the geographic location of a
 router needs to be stored in IRR, it may be tempting to add a new
 class called, say router-location class.  However, the information
 better belongs to the inet-rtr class, perhaps in a new attribute
 called location.

10.4 Extensions by changing the syntax of existing RPSL attributes

 If all of the methods described above fail to provide the desired
 extension, it may be necessary to change the syntax of RPSL. Any
 change in RPSL syntax must provide backwards compatibility, and
 should be considered only as a last resort since full compatibility

Alaettinoglu, et al. Standards Track [Page 55] RFC 2622 RPSL June 1999

 may not be achievable.  However, we require that the old syntax to be
 still valid.

11 Security Considerations

 This document describes RPSL, a language for expressing routing
 policies.  The language defines a maintainer (mntner class) object
 which is the entity which controls or "maintains" the objects stored
 in a database expressed by RPSL. Requests from maintainers can be
 authenticated with various techniques as defined by the "auth"
 attribute of the maintainer object.
 The exact protocols used by IRR's to communicate RPSL objects is
 beyond the scope of this document, but it is envisioned that several
 techniques may be used, ranging from interactive query/update
 protocols to store and forward protocols similar to or based on
 electronic mail (or even voice telephone calls).  Regardless of which
 protocols are used in a given situation, it is expected that
 appropriate security techniques such as IPSEC, TLS or PGP/MIME will
 be utilized.

12 Acknowledgements

 We would like to thank Jessica Yu, Randy Bush, Alan Barrett, Bill
 Manning, Sue Hares, Ramesh Govindan, Kannan Varadhan, Satish Kumar,
 Craig Labovitz, Rusty Eddy, David J. LeRoy, David Whipple, Jon
 Postel, Deborah Estrin, Elliot Schwartz, Joachim Schmitz, Mark Prior,
 Tony Przygienda, David Woodgate, Rob Coltun, Sanjay Wadhwa, Ardas
 Cilingiroglu, and the participants of the IETF RPS Working Group for
 various comments and suggestions.

References

 [1] Internet routing registry. procedures.
     http://www.ra.net/RADB.tools.docs/,
     http://www.ripe.net/db/doc.html.
 [2] Nsfnet policy routing database (prdb). Maintained by MERIT
     Network Inc., Ann Arbor, Michigan. Contents available from
     nic.merit.edu.:/nsfnet/announced.networks/nets.tag.now by
     anonymous ftp.
 [3] Alaettinouglu, C., Bates, T., Gerich, E., Karrenberg, D., Meyer,
     D., Terpstra, M. and C. Villamizer, "Routing Policy Specification
     Language (RPSL)", RFC 2280, January 1998.

Alaettinoglu, et al. Standards Track [Page 56] RFC 2622 RPSL June 1999

 [4] C. Alaettinouglu, D. Meyer, and J. Schmitz. Application of
     routing policy specification language (rpsl) on the internet.
     Work in Progress.
 [5] T. Bates. Specifying an `internet router' in the routing
     registry.  Technical Report RIPE-122, RIPE, RIPE NCC, Amsterdam,
     Netherlands, October 1994.
 [6] T. Bates, E. Gerich, L. Joncheray, J-M. Jouanigot, D. Karrenberg,
     M. Terpstra, and J. Yu. Representation of ip routing policies in
     a routing registry. Technical Report ripe-181, RIPE, RIPE NCC,
     Amsterdam, Netherlands, October 1994.
 [7] Bates, T., Gerich, E., Joncheray, L., Jouanigot, J-M.,
     Karrenberg, D., Terpstra, M. and J. Yu, " Representation of IP
     Routing Policies in a Routing Registry", RFC 1786, March 1995.
 [8] T. Bates, J-M. Jouanigot, D. Karrenberg, P. Lothberg, and M.
     Terpstra.  Representation of ip routing policies in the ripe
     database. Technical Report ripe-81, RIPE, RIPE NCC, Amsterdam,
     Netherlands, February 1993.
 [9] Chandra, R., Traina, P. and T. Li, "BGP Communities Attribute",
     RFC 1997, August 1996.
[10] Crocker, D., "Standard for ARPA Internet Text Messages", STD 11,
     RFC 822, August 1982.
[11] Fuller, V., Li, T., Yu, J. and K. Varadhan, "Classless Inter-
     Domain Routing (CIDR): an Address Assignment and Aggregation
     Strategy", RFC 1519, September 1993.
[12] D. Karrenberg and T. Bates. Description of inter-as networks in
     the ripe routing registry. Technical Report RIPE-104, RIPE, RIPE
     NCC, Amsterdam, Netherlands, December 1993.
[13] D. Karrenberg and M. Terpstra. Authorisation and notification of
     changes in the ripe database. Technical Report ripe-120, RIPE,
     RIPE NCC, Amsterdam, Netherlands, October 1994.
[14] B. W. Kernighan and D. M. Ritchie. The C Programming Language.
     Prentice-Hall, 1978.
[15] A. Lord and M. Terpstra. Ripe database template for networks and
     persons. Technical Report ripe-119, RIPE, RIPE NCC, Amsterdam,
     Netherlands, October 1994.

Alaettinoglu, et al. Standards Track [Page 57] RFC 2622 RPSL June 1999

[16] A. M. R. Magee. Ripe ncc database documentation. Technical Report
     RIPE-157, RIPE, RIPE NCC, Amsterdam, Netherlands, May 1997.
[17] Mockapetris, P., "Domain names - concepts and facilities", STD
     13, RFC 1034, November 1987.
[18] Y. Rekhter. Inter-domain routing protocol (idrp). Journal of
     Internetworking Research and Experience, 4:61--80, 1993.
[19] Rekhter Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC
     1771, March 1995.
[20] C. Villamizar, C. Alaettinouglu, D. Meyer, S. Murphy, and C.
     Orange.  Routing policy system security", Work in Progress.
[21] Villamizar, C., Chandra, R. and R. Govindan, "BGP Route Flap
     Damping", RFC 2439, November 1998.
[22] J. Zsako, "PGP authentication for ripe database updates", Work in
     Progress.

Alaettinoglu, et al. Standards Track [Page 58] RFC 2622 RPSL June 1999

A Routing Registry Sites

 The set of routing registries as of November 1996 are RIPE, RADB,
 CANet, MCI and ANS. You may contact one of these registries to find
 out the current list of registries.

B Grammar Rules

 In this section we provide formal grammar rules for RPSL. Basic data
 types are defined in Section 2.  We do not provide formal grammar
 rules for attributes whose values are of basic types or list of basic
 types.  The rules are written using the input language of GNU Bison
 parser.  Hence, they can be cut and pasted to that program.

Generic Attributes changed_attribute: ATTR_CHANGED TKN_EMAIL TKN_INT aut-num class * as_expression / opt_as_expression: | as_expression as_expression: as_expression OP_OR as_expression_term | as_expression_term as_expression_term: as_expression_term OP_AND as_expression_factor | as_expression_term KEYW_EXCEPT as_expression_factor | as_expression_factor as_expression_factor: '(' as_expression ')' | as_expression_operand as_expression_operand: TKN_ASNO | TKN_ASNAME router_expression / opt_router_expression: | router_expression opt_router_expression_with_at: | KEYW_AT router_expression router_expression: router_expression OP_OR router_expression_term | router_expression_term Alaettinoglu, et al. Standards Track [Page 59] RFC 2622 RPSL June 1999 router_expression_term: router_expression_term OP_AND router_expression_factor | router_expression_term KEYW_EXCEPT router_expression_factor | router_expression_factor router_expression_factor: '(' router_expression ')' | router_expression_operand router_expression_operand: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME peering / peering: as_expression opt_router_expression opt_router_expression_with_at | TKN_PRNGNAME action opt_action: | KEYW_ACTION action action: single_action | action single_action single_action: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')' ';' | TKN_RP_ATTR TKN_OPERATOR list_item ';' | TKN_RP_ATTR '(' generic_list ')' ';' | TKN_RP_ATTR '[' generic_list ']' ';' | ';' filter filter: filter OP_OR filter_term | filter filter_term %prec OP_OR | filter_term filter_term : filter_term OP_AND filter_factor | filter_factor filter_factor : OP_NOT filter_factor | '(' filter ')' | filter_operand filter_operand: KEYW_ANY | '<' filter_aspath '>' | filter_rp_attribute | TKN_FLTRNAME | filter_prefix Alaettinoglu, et al. Standards Track [Page 60] RFC 2622 RPSL June 1999 filter_prefix: filter_prefix_operand OP_MS | filter_prefix_operand filter_prefix_operand: TKN_ASNO | KEYW_PEERAS | TKN_ASNAME | TKN_RSNAME | '{' opt_filter_prefix_list '}' opt_filter_prefix_list: | filter_prefix_list filter_prefix_list: filter_prefix_list_prefix | filter_prefix_list ',' filter_prefix_list_prefix filter_prefix_list_prefix: TKN_PRFXV4 | TKN_PRFXV4RNG filter_aspath: filter_aspath '|' filter_aspath_term | filter_aspath_term filter_aspath_term: filter_aspath_term filter_aspath_closure | filter_aspath_closure filter_aspath_closure: filter_aspath_closure '*' | filter_aspath_closure '?' | filter_aspath_closure '+' | filter_aspath_factor filter_aspath_factor: '^' | '$' | '(' filter_aspath ')' | filter_aspath_no filter_aspath_no: TKN_ASNO | KEYW_PEERAS | TKN_ASNAME | '.' | '[' filter_aspath_range ']' | '[' '^' filter_aspath_range ']' filter_aspath_range: | filter_aspath_range TKN_ASNO | filter_aspath_range KEYW_PEERAS | filter_aspath_range '.' | filter_aspath_range TKN_ASNO '-' TKN_ASNO | filter_aspath_range TKN_ASNAME Alaettinoglu, et al. Standards Track [Page 61] RFC 2622 RPSL June 1999 filter_rp_attribute: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')' | TKN_RP_ATTR TKN_OPERATOR list_item | TKN_RP_ATTR '(' generic_list ')' | TKN_RP_ATTR '[' generic_list ']' peering action pair / import_peering_action_list: KEYW_FROM peering opt_action | import_peering_action_list KEYW_FROM peering opt_action export_peering_action_list: KEYW_TO peering opt_action | export_peering_action_list KEYW_TO peering opt_action import/export factor import_factor: import_peering_action_list KEYW_ACCEPT filter import_factor_list: import_factor ';' | import_factor_list import_factor ';' export_factor: export_peering_action_list KEYW_ANNOUNCE filter export_factor_list: export_factor ';' | export_factor_list export_factor ';' import/export term import_term: import_factor ';' | '{' import_factor_list '}' export_term: export_factor ';' | '{' export_factor_list '}' import/export expression import_expression: import_term | import_term KEYW_REFINE import_expression | import_term KEYW_EXCEPT import_expression export_expression: export_term | export_term KEYW_REFINE export_expression | export_term KEYW_EXCEPT export_expression protocol / opt_protocol_from: | KEYW_PROTOCOL tkn_word Alaettinoglu, et al. Standards Track [Page 62] RFC 2622 RPSL June 1999 opt_protocol_into: | KEYW_INTO tkn_word import/export attributes import_attribute: ATTR_IMPORT | ATTR_IMPORT opt_protocol_from opt_protocol_into import_factor export_attribute: ATTR_EXPORT | ATTR_EXPORT opt_protocol_from opt_protocol_into export_factor opt_default_filter: | KEYW_NETWORKS filter default_attribute: ATTR_DEFAULT KEYW_TO peering filter_attribute: ATTR_FILTER filter peering_attribute: ATTR_PEERING peering inet-rtr class ifaddr_attribute: ATTR_IFADDR TKN_IPV4 KEYW_MASKLEN TKN_INT opt_action peer attribute opt_peer_options: | peer_options peer_options: peer_option | peer_options ',' peer_option peer_option: tkn_word '(' generic_list ')' peer_id: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME | TKN_PRNGNAME peer_attribute: ATTR_PEER tkn_word peer_id opt_peer_options route class * aggr_bndry_attribute: ATTR_AGGR_BNDRY as_expression aggr_mtd_attribute: ATTR_AGGR_MTD KEYW_INBOUND | ATTR_AGGR_MTD KEYW_OUTBOUND opt_as_expression Alaettinoglu, et al. Standards Track [Page 63] RFC 2622 RPSL June 1999 inject attribute opt_inject_expression: | KEYW_UPON inject_expression inject_expression: inject_expression OP_OR inject_expression_term | inject_expression_term inject_expression_term: inject_expression_term OP_AND inject_expression_factor | inject_expression_factor inject_expression_factor: '(' inject_expression ')' | inject_expression_operand inject_expression_operand: KEYW_STATIC | KEYW_HAVE_COMPONENTS '{' opt_filter_prefix_list '}' | KEYW_EXCLUDE '{' opt_filter_prefix_list '}' inject_attribute: ATTR_INJECT opt_router_expression_with_at opt_action opt_inject_expression components attribute opt_atomic: | KEYW_ATOMIC components_list: | filter | components_list KEYW_PROTOCOL tkn_word filter components_attribute: ATTR_COMPONENTS opt_atomic components_list route-set * opt_rs_members_list: /* empty list */ | rs_members_list rs_members_list: rs_member | rs_members_list ',' rs_member rs_member: TKN_ASNO | TKN_ASNO OP_MS | TKN_ASNAME | TKN_ASNAME OP_MS | TKN_RSNAME | TKN_RSNAME OP_MS | TKN_PRFXV4 Alaettinoglu, et al. Standards Track [Page 64] RFC 2622 RPSL June 1999 | TKN_PRFXV4RNG rs_members_attribute: ATTR_RS_MEMBERS opt_rs_members_list dictionary rpattr_attribute: ATTR_RP_ATTR TKN_WORD methods | ATTR_RP_ATTR TKN_RP_ATTR methods methods: method | methods method method: TKN_WORD '(' ')' | TKN_WORD '(' typedef_type_list ')' | TKN_WORD '(' typedef_type_list ',' TKN_3DOTS ')' | KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ')' | KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ',' TKN_3DOTS ')' typedef attribute typedef_attribute: ATTR_TYPEDEF TKN_WORD typedef_type typedef_type_list: typedef_type | typedef_type_list ',' typedef_type typedef_type: KEYW_UNION typedef_type_list | KEYW_RANGE KEYW_OF typedef_type | TKN_WORD | TKN_WORD '[' TKN_INT ',' TKN_INT ']' | TKN_WORD '[' TKN_REAL ',' TKN_REAL ']' | TKN_WORD '[' enum_list ']' | KEYW_LIST '[' TKN_INT ':' TKN_INT ']' KEYW_OF typedef_type | KEYW_LIST KEYW_OF typedef_type enum_list: tkn_word | enum_list ',' tkn_word protocol attribute protocol_attribute: ATTR_PROTOCOL tkn_word protocol_options protocol_options: | protocol_options protocol_option protocol_option: KEYW_MANDATORY method | KEYW_OPTIONAL method Token Definitions * Alaettinoglu, et al. Standards Track [Page 65] RFC 2622 RPSL June 1999 flex macros used in token definitions / INT digit+ SINT [+-]?{INT} REAL [+-]?{INT}?\.{INT}({WS}*E{WS}*[+-]?{INT})? NAME alpha(alnum)? ASNO AS{INT} ASNAME AS-alnum RSNAME RS-alnum RTRSNAME RTRS-alnum PRNGNAME PRNG-alnum FLTRNAME FLTR-alnum IPV4 [0-9]+(\.[0-9]+){3,3} PRFXV4 {IPV4}\/[0-9]+ PRFXV4RNG {PRFXV4}("^+"|"^-"|"^"{INT}|"^"{INT}-{INT}) ENAMECHAR [^()<>,;:\\\"\.[\] \t\r] ENAME ({ENAMECHAR}+(\.{ENAMECHAR}+)*\.?)|(\"[^\"@\\\r\n]+\") DNAME [[:alnum:]_-]+ Token Definitions TKN_INT {SINT} TKN_INT {INT}:{INT} if each {INT} is two octets TKN_INT {INT}.{INT}.{INT}.{INT} if each {INT} is one octet TKN_REAL {REAL} TKN_STRING Same as in programming language C TKN_IPV4 {IPV4} TKN_PRFXV4 {PRFXV4} TKN_PRFXV4RNG {PRFXV4RNG} TKN_ASNO {ASNO} TKN_ASNAME 1)

1)
{ASNO}|peeras|{ASNAME}):)*{ASNAME}\
              (:({ASNO}|peeras|{ASNAME}))*
TKN_RSNAME (({ASNO}|peeras|{RSNAME}):)*{RSNAME}\
              (:({ASNO}|peeras|{RSNAME}))*
TKN_RTRSNAME (({ASNO}|peeras|{RTRSNAME}):)*{RTRSNAME}\
              (:({ASNO}|peeras|{RTRSNAME}))*
TKN_PRNGNAME (({ASNO}|peeras|{PRNGNAME}):)*{PRNGNAME}\
              (:({ASNO}|peeras|{PRNGNAME}))*
TKN_FLTRNAME (({ASNO}|peeras|{FLTRNAME}):)*{FLTRNAME}\
              (:({ASNO}|peeras|{FLTRNAME}))*
TKN_BOOLEAN true|false TKN_RP_ATTR {NAME} if defined in dictionary TKN_WORD {NAME} TKN_DNS {DNAME}("."{DNAME})+ TKN_EMAIL {ENAME}@({DNAME}("."{DNAME})+|{IPV4}) Alaettinoglu, et al. Standards Track [Page 66] RFC 2622 RPSL June 1999 C Changes from RFC 2280
 RFC 2280 [3] contains an earlier version of RPSL. This section
 summarizes the changes since then.  They are as follows:
o  It is now possible to write integers as sequence of four 1-octet
   integers (e.g. 1.1.1.1) or as sequence of two 2-octet integers
   (e.g.  3561:70).  Please see Section 2.
o  The definition of address prefix range is extended so that an
   address prefix is also an address prefix range.  Please see Section
   2.
o  The semantics for a range operator applied to a set containing
   address prefix ranges is defined (e.g. {30.0.0.0/8^24-28}^27-30).
   Please see Section 2.
o  All dates are now in UTC. Please see Section 2.
o  Plus ('+') character is added to space and tab characters to split
   an attribute's value to multiple lines (i.e. by starting the
   following lines with a space, a tab or a plus ('+') character).
   Please see Section 2.
o  The withdrawn attribute of route class is removed from the
   language.
o  filter-set class is introduced.  Please see Section 5.4.
o  rtr-set class is introduced.  Please see Section 5.5.
o  peering-set class is introduced.  Please see Section 5.6.
o  Filters can now refer to filter-set names.  Please see Section 5.4.
o  Peerings can now refer to peering-set, rtr-set names.  Both local
   and peer routers can be specified using router expressions.  Please
   see Section 5.6.
o  The peer attribute of the inet-rtr class can refer to peering-set,
   rtr-set names.  Please see Section 9.
o  The syntax and semantics of union, and list types and typedef
   attribute have changed.  Please see Section 7.
o  In the initial dictionary, the typedef attribute defining the
   community_elm, rp-attribute defining the community attribute has
   changed.  Please see Section 7.
Alaettinoglu, et al. Standards Track [Page 67] RFC 2622 RPSL June 1999
o  Guideliness for extending RPSL is added.  Please see Section 10.
o  Formal grammar rules are added.  Please see Appendix B.
D Authors' Addresses
 Cengiz Alaettinoglu
 USC/Information Sciences Institute
 EMail: cengiz@isi.edu
 Curtis Villamizar
 Avici Systems
 EMail: curtis@avici.com
 Elise Gerich
 At Home Network
 EMail: epg@home.net
 David Kessens
 Qwest Communications
 EMail: David.Kessens@qwest.net
 David Meyer
 University of Oregon
 EMail: meyer@antc.uoregon.edu
 Tony Bates
 Cisco Systems, Inc.
 EMail: tbates@cisco.com
 Daniel Karrenberg
 RIPE NCC
 EMail: dfk@ripe.net
 Marten Terpstra
 c/o Bay Networks, Inc.
 EMail: marten@BayNetworks.com
Alaettinoglu, et al. Standards Track [Page 68] RFC 2622 RPSL June 1999 Full Copyright Statement
 Copyright (C) The Internet Society (1999).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implmentation may be prepared, copied, published and
 distributed, in whole or in part, without restriction of any kind,
 provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of developing
 Internet standards in which case the procedures for copyrights defined
 in the Internet Standards process must be followed, or as required to
 translate it into languages other than English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
 NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN
 WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
 Funding for the RFC Editor function is currently provided by the
 Internet Society.
Alaettinoglu, et al. Standards Track [Page 69]
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