GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc5214

Network Working Group F. Templin Request for Comments: 5214 Boeing Phantom Works Obsoletes: 4214 T. Gleeson Category: Informational Cisco Systems K.K.

                                                             D. Thaler
                                                 Microsoft Corporation
                                                            March 2008
      Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

IESG Note

 The IESG thinks that this work is related to IETF work done in WG
 softwires, but this does not prevent publishing.

Abstract

 The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) connects
 dual-stack (IPv6/IPv4) nodes over IPv4 networks.  ISATAP views the
 IPv4 network as a link layer for IPv6 and supports an automatic
 tunneling abstraction similar to the Non-Broadcast Multiple Access
 (NBMA) model.

Templin, et al. Informational [Page 1] RFC 5214 ISATAP March 2008

Table of Contents

 1. Introduction ....................................................2
 2. Requirements ....................................................3
 3. Terminology .....................................................3
 4. Domain of Applicability .........................................4
 5. Node Requirements ...............................................4
 6. Addressing Requirements .........................................4
    6.1. ISATAP Interface Identifiers ...............................4
    6.2. ISATAP Interface Address Configuration .....................5
    6.3. Multicast/Anycast ..........................................5
 7. Automatic Tunneling .............................................5
    7.1. Encapsulation ..............................................5
    7.2. Handling ICMPv4 Errors .....................................5
    7.3. Decapsulation ..............................................6
    7.4. Link-Local Addresses .......................................6
    7.5. Neighbor Discovery over Tunnels ............................6
 8. Neighbor Discovery for ISATAP Interfaces ........................6
    8.1. Conceptual Model of a Host .................................7
    8.2. Router and Prefix Discovery - Router Specification .........7
    8.3. Router and Prefix Discovery - Host Specification ...........7
         8.3.1. Host Variables ......................................7
         8.3.2. Potential Router List Initialization ................7
         8.3.3. Processing Received Router Advertisements ...........8
         8.3.4. Sending Router Solicitations ........................8
    8.4. Neighbor Unreachability Detection ..........................9
 9. Site Administration Considerations ..............................9
 10. Security Considerations ........................................9
 11. IANA Considerations ...........................................10
 12. Acknowledgments ...............................................10
 13. References ....................................................11
    13.1. Normative References .....................................11
    13.2. Informative References ...................................12
 Appendix A. Modified EUI-64 Addresses in the IANA Ethernet
           Address Block ...........................................13

1. Introduction

 This document specifies a simple mechanism called the Intra-Site
 Automatic Tunnel Addressing Protocol (ISATAP) that connects
 dual-stack (IPv6/IPv4) nodes over IPv4 networks.  Dual-stack nodes
 use ISATAP to automatically tunnel IPv6 packets in IPv4, i.e., ISATAP
 views the IPv4 network as a link layer for IPv6.
 ISATAP enables automatic tunneling whether global or private IPv4
 addresses are used, and it presents a Non-Broadcast Multiple Access
 (NBMA) abstraction similar to [RFC2491],[RFC2492],[RFC2529], and
 [RFC3056].

Templin, et al. Informational [Page 2] RFC 5214 ISATAP March 2008

 The main objectives of this document are to: 1) describe the domain
 of applicability, 2) specify addressing requirements, 3) specify
 automatic tunneling using ISATAP, 4) specify the operation of IPv6
 Neighbor Discovery over ISATAP interfaces, and 5) discuss Site
 Administration, Security, and IANA considerations.

2. Requirements

 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
 SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
 document, are to be interpreted as described in [RFC2119].
 This document also uses internal conceptual variables to describe
 protocol behavior and external variables that an implementation must
 allow system administrators to change.  The specific variable names,
 how their values change, and how their settings influence protocol
 behavior are provided in order to demonstrate protocol behavior.  An
 implementation is not required to have them in the exact form
 described here, as long as its external behavior is consistent with
 that described in this document.

3. Terminology

 The terminology of [RFC2460] and [RFC4861] applies to this document.
 The following additional terms are defined:
 ISATAP node/host/router:
    A dual-stack (IPv6/IPv4) node/host/router that implements the
    specifications in this document.
 ISATAP interface:
    An ISATAP node's Non-Broadcast Multi-Access (NBMA) IPv6 interface,
    used for automatic tunneling of IPv6 packets in IPv4.
 ISATAP interface identifier:
    An IPv6 interface identifier with an embedded IPv4 address
    constructed as specified in Section 6.1.
 ISATAP address:
    An IPv6 unicast address that matches an on-link prefix on an
    ISATAP interface of the node, and that includes an ISATAP
    interface identifier.
 locator:
    An IPv4 address-to-interface mapping; i.e., a node's IPv4 address
    and its associated interface.

Templin, et al. Informational [Page 3] RFC 5214 ISATAP March 2008

 locator set:
    A set of locators associated with an ISATAP interface.  Each
    locator in the set belongs to the same site.

4. Domain of Applicability

 The domain of applicability for this technical specification is
 automatic tunneling of IPv6 packets in IPv4 for ISATAP nodes within
 sites that observe the security considerations found in this
 document, including host-to-router, router-to-host, and host-to-host
 automatic tunneling in certain enterprise networks and 3GPP/3GPP2
 wireless operator networks.  (Other scenarios with a sufficient trust
 basis ensured by the mechanisms specified in this document also fall
 within this domain of applicability.)
 Extensions to the above domain of applicability (e.g., by combining
 the mechanisms in this document with those in other technical
 specifications) are out of the scope of this document.

5. Node Requirements

 ISATAP nodes observe the common functionality requirements for IPv6
 nodes found in [RFC4294] and the requirements for dual IP layer
 operation found in Section 2 of [RFC4213].  They also implement the
 additional features specified in this document.

6. Addressing Requirements

6.1. ISATAP Interface Identifiers

 ISATAP interface identifiers are constructed in Modified EUI-64
 format per Section 2.5.1 of [RFC4291] by concatenating the 24-bit
 IANA OUI (00-00-5E), the 8-bit hexadecimal value 0xFE, and a 32-bit
 IPv4 address in network byte order as follows:
 |0              1|1              3|3                              6|
 |0              5|6              1|2                              3|
 +----------------+----------------+--------------------------------+
 |000000ug00000000|0101111011111110|mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm|
 +----------------+----------------+--------------------------------+
 When the IPv4 address is known to be globally unique, the "u" bit
 (universal/local) is set to 1; otherwise, the "u" bit is set to 0.
 "g" is the individual/group bit, and "m" represents the bits of the
 IPv4 address.

Templin, et al. Informational [Page 4] RFC 5214 ISATAP March 2008

 Per Section 2.5.1 of [RFC4291], ISATAP nodes are not required to
 validate that interface identifiers created with modified EUI-64
 tokens with the "u" bit set to universal are unique.

6.2. ISATAP Interface Address Configuration

 Each ISATAP interface configures a set of locators consisting of IPv4
 address-to-interface mappings from a single site; i.e., an ISATAP
 interface's locator set MUST NOT span multiple sites.
 When an IPv4 address is removed from an interface, the corresponding
 locator SHOULD be removed from its associated locator set(s).  When a
 new IPv4 address is assigned to an interface, the corresponding
 locator MAY be added to the appropriate locator set(s).
 ISATAP interfaces form ISATAP interface identifiers from IPv4
 addresses in their locator set and use them to create link-local
 ISATAP addresses (Section 5.3 of [RFC4862]).

6.3. Multicast/Anycast

 It is not possible to assume the general availability of wide-area
 IPv4 multicast, so (unlike 6over4 [RFC2529]) ISATAP must assume that
 its underlying IPv4 carrier network only has unicast capability.
 Support for IPv6 multicast over ISATAP interfaces is not described in
 this document.
 Similarly, support for Reserved IPv6 Subnet Anycast Addresses is not
 described in this document.

7. Automatic Tunneling

 ISATAP interfaces use the basic tunneling mechanisms specified in
 Section 3 of [RFC4213].  The following sub-sections describe
 additional specifications.

7.1. Encapsulation

 ISATAP addresses are mapped to a link-layer address by a static
 computation; i.e., the last four octets are treated as an IPv4
 address.

7.2. Handling ICMPv4 Errors

 ISATAP interfaces SHOULD process Address Resolution Protocol (ARP)
 failures and persistent ICMPv4 errors as link-specific information
 indicating that a path to a neighbor may have failed (Section 7.3.3
 of [RFC4861]).

Templin, et al. Informational [Page 5] RFC 5214 ISATAP March 2008

7.3. Decapsulation

 The specification in Section 3.6 of [RFC4213] is used.  Additionally,
 when an ISATAP node receives an IPv4 protocol 41 datagram that does
 not belong to a configured tunnel interface, it determines whether
 the packet's IPv4 destination address and arrival interface match a
 locator configured in an ISATAP interface's locator set.
 If an ISATAP interface that configures a matching locator is found,
 the decapsulator MUST verify that the packet's IPv4 source address is
 correct for the encapsulated IPv6 source address.  The IPv4 source
 address is correct if:
    o  the IPv6 source address is an ISATAP address that embeds the
       IPv4 source address in its interface identifier, or
    o  the IPv4 source address is a member of the Potential Router
       List (see Section 8.1).
 Packets for which the IPv4 source address is incorrect for this
 ISATAP interface are checked to determine whether they belong to
 another tunnel interface.

7.4. Link-Local Addresses

 ISATAP interfaces use link-local addresses constructed as specified
 in Section 6 of this document.

7.5. Neighbor Discovery over Tunnels

 ISATAP interfaces use the specifications for neighbor discovery found
 in the following section of this document.

8. Neighbor Discovery for ISATAP Interfaces

 ISATAP interfaces use the neighbor discovery mechanisms specified in
 [RFC4861].  The following sub-sections describe specifications that
 are also implemented.

Templin, et al. Informational [Page 6] RFC 5214 ISATAP March 2008

8.1. Conceptual Model of a Host

 To the list of Conceptual Data Structures (Section 5.1 of [RFC4861]),
 ISATAP interfaces add the following:
 Potential Router List (PRL)
    A set of entries about potential routers; used to support router
    and prefix discovery.  Each entry ("PRL(i)") has an associated
    timer ("TIMER(i)"), and an IPv4 address ("V4ADDR(i)") that
    represents a router's advertising ISATAP interface.

8.2. Router and Prefix Discovery - Router Specification

 Advertising ISATAP interfaces send Solicited Router Advertisement
 messages as specified in Section 6.2.6 of [RFC4861] except that the
 messages are sent directly to the soliciting node; i.e., they might
 not be received by other nodes on the link.

8.3. Router and Prefix Discovery - Host Specification

 The Host Specification in Section 6.3 of [RFC4861] is used.  The
 following sub-sections describe specifications added by ISATAP
 interfaces.

8.3.1. Host Variables

 To the list of host variables (Section 6.3.2 of [RFC4861]), ISATAP
 interfaces add the following:
 PrlRefreshInterval
    Time in seconds between successive refreshments of the PRL after
    initialization.  The designated value of all ones (0xffffffff)
    represents infinity.
    Default: 3600 seconds
 MinRouterSolicitInterval
    Minimum time in seconds between successive solicitations of the
    same advertising ISATAP interface.  The designated value of all
    ones (0xffffffff) represents infinity.

8.3.2. Potential Router List Initialization

 ISATAP nodes initialize an ISATAP interface's PRL with IPv4 addresses
 acquired via manual configuration, a DNS Fully Qualified Domain Name
 (FQDN) [RFC1035], a DHCPv4 [RFC2131] vendor-specific option, or an
 unspecified alternate method.  Domain names are acquired via manual

Templin, et al. Informational [Page 7] RFC 5214 ISATAP March 2008

 configuration, receipt of a DHCPv4 Domain Name option [RFC2132], or
 an unspecified alternate method.  FQDNs are resolved into IPv4
 addresses through a static host file lookup, querying the DNS
 service, querying a site-specific name service, or with an
 unspecified alternate method.
 After initializing an ISATAP interface's PRL, the node sets a timer
 for the interface to PrlRefreshInterval seconds and re-initializes
 the interface's PRL as specified above when the timer expires.  When
 an FQDN is used, and when it is resolved via a service that includes
 Times to Live (TTLs) with the IPv4 addresses returned (e.g., DNS 'A'
 resource records [RFC1035]), the timer SHOULD be set to the minimum
 of PrlRefreshInterval and the minimum TTL returned.  (Zero-valued
 TTLs are interpreted to mean that the PRL is re-initialized before
 each Router Solicitation event; see Section 8.3.4.)

8.3.3. Processing Received Router Advertisements

 To the list of checks for validating Router Advertisement messages
 (Section 6.1.2 of [RFC4861]), ISATAP interfaces add the following:
 o  IP Source Address is a link-local ISATAP address that embeds
    V4ADDR(i) for some PRL(i).
 Valid Router Advertisements received on an ISATAP interface are
 processed as specified in Section 6.3.4 of [RFC4861].

8.3.4. Sending Router Solicitations

 To the list of events after which Router Solicitation messages may be
 sent (Section 6.3.7 of [RFC4861]), ISATAP interfaces add the
 following:
 o  TIMER(i) for some PRL(i) expires.
 Since unsolicited Router Advertisements may be incomplete and/or
 absent, ISATAP nodes MAY schedule periodic Router Solicitation events
 for certain PRL(i)s by setting the corresponding TIMER(i).
 When periodic Router Solicitation events are scheduled, the node
 SHOULD set TIMER(i) so that the next event will refresh remaining
 lifetimes stored for PRL(i) before they expire, including the Router
 Lifetime, Valid Lifetimes received in Prefix Information Options, and
 Route Lifetimes received in Route Information Options [RFC4191].
 TIMER(i) MUST be set to no less than MinRouterSolicitInterval seconds
 where MinRouterSolicitInterval is configurable for the node, or for a
 specific PRL(i), with a conservative default value (e.g., 2 minutes).

Templin, et al. Informational [Page 8] RFC 5214 ISATAP March 2008

 When TIMER(i) expires, the node sends Router Solicitation messages as
 specified in Section 6.3.7 of [RFC4861] except that the messages are
 sent directly to PRL(i); i.e., they might not be received by other
 routers.  While the node continues to require periodic Router
 Solicitation events for PRL(i), and while PRL(i) continues to act as
 a router, the node resets TIMER(i) after each expiration event as
 described above.

8.4. Neighbor Unreachability Detection

 ISATAP hosts SHOULD perform Neighbor Unreachability Detection
 (Section 7.3 of [RFC4861]).  ISATAP routers MAY perform Neighbor
 Unreachability Detection, but this might not scale in all
 environments.
 After address resolution, ISATAP hosts SHOULD perform an initial
 reachability confirmation by sending Neighbor Solicitation messages
 and receiving a Neighbor Advertisement message.  ISATAP routers MAY
 perform this initial reachability confirmation, but this might not
 scale in all environments.

9. Site Administration Considerations

 Site administrators maintain a Potential Router List (PRL) of IPv4
 addresses representing advertising ISATAP interfaces of routers.
 The PRL is commonly maintained as an FQDN for the ISATAP service in
 the site's name service (see Section 8.3.2).  There are no mandatory
 rules for the selection of the FQDN, but site administrators are
 encouraged to use the convention "isatap.domainname" (e.g.,
 isatap.example.com).
 When the site's name service includes TTLs with the IPv4 addresses
 returned, site administrators SHOULD configure the TTLs with
 conservative values to minimize control traffic.

10. Security Considerations

 Implementers should be aware that, in addition to possible attacks
 against IPv6, security attacks against IPv4 must also be considered.
 Use of IP security at both IPv4 and IPv6 levels should nevertheless
 be avoided, for efficiency reasons.  For example, if IPv6 is running
 encrypted, encryption of IPv4 would be redundant unless traffic
 analysis is felt to be a threat.  If IPv6 is running authenticated,
 then authentication of IPv4 will add little.  Conversely, IPv4
 security will not protect IPv6 traffic once it leaves the ISATAP
 domain.  Therefore, implementing IPv6 security is required even if
 IPv4 security is available.

Templin, et al. Informational [Page 9] RFC 5214 ISATAP March 2008

 The threats associated with IPv6 Neighbor Discovery are described in
 [RFC3756].
 There is a possible spoofing attack in which spurious ip-protocol-41
 packets are injected into an ISATAP link from outside.  Since an
 ISATAP link spans an entire IPv4 site, restricting access to the link
 can be achieved by restricting access to the site; i.e., by having
 site border routers implement IPv4 ingress filtering and ip-
 protocol-41 filtering.
 Another possible spoofing attack involves spurious ip-protocol-41
 packets injected from within an ISATAP link by a node pretending to
 be a router.  The Potential Router List (PRL) provides a list of IPv4
 addresses representing advertising ISATAP interfaces of routers that
 hosts use in filtering decisions.  Site administrators should ensure
 that the PRL is kept up to date, and that the resolution mechanism
 (see Section 9) cannot be subverted.
 The use of temporary addresses [RFC4941] and Cryptographically
 Generated Addresses [RFC3972] on ISATAP interfaces is outside the
 scope of this specification.

11. IANA Considerations

 The IANA has specified the format for Modified EUI-64 address
 construction (Appendix A of [RFC4291]) in the IANA Ethernet Address
 Block.  The text in the Appendix of this document has been offered as
 an example specification.  The current version of the IANA registry
 for Ether Types can be accessed at:
 http://www.iana.org/assignments/ethernet-numbers

12. Acknowledgments

 The ideas in this document are not original, and the authors
 acknowledge the original architects.  Portions of this work were
 sponsored through SRI International and Nokia and Boeing internal
 projects and government contracts.  Government sponsors include
 Monica Farah Stapleton and Russell Langan (U.S. Army CECOM ASEO) and
 Dr. Allen Moshfegh (U.S. Office of Naval Research).  SRI
 International sponsors include Dr. Mike Frankel, J. Peter
 Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry.
 The following are acknowledged for providing peer review input: Jim
 Bound, Rich Draves, Cyndi Jung, Ambatipudi Sastry, Aaron Schrader,
 Ole Troan, and Vlad Yasevich.

Templin, et al. Informational [Page 10] RFC 5214 ISATAP March 2008

 The following are acknowledged for their significant contributions:
 Marcelo Albuquerque, Brian Carpenter, Alain Durand, Hannu Flinck,
 Jason Goldschmidt, Christian Huitema, Nathan Lutchansky, Karen
 Nielsen, Mohan Parthasarathy, Chirayu Patel, Art Shelest, Markku
 Savela, Pekka Savola, Margaret Wasserman, Brian Zill, and members of
 the IETF IPv6 and V6OPS working groups.  Mohit Talwar contributed to
 earlier versions of this document.
 The authors acknowledge the work done by Brian Carpenter and Cyndi
 Jung in RFC 2529 that introduced the concept of intra-site automatic
 tunneling.  This concept was later called: "Virtual Ethernet" and
 researched by Quang Nguyen under the guidance of Dr. Lixia Zhang.

13. References

13.1. Normative References

 [RFC1035]  Mockapetris, P., "Domain names - implementation and
            specification", STD 13, RFC 1035, November 1987.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol", RFC
            2131, March 1997.
 [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
            Extensions", RFC 2132, March 1997.
 [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
            (IPv6) Specification", RFC 2460, December 1998.
 [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
            "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
            September 2007.
 [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
            for IPv6 Hosts and Routers", RFC 4213, October 2005.
 [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
            Architecture", RFC 4291, February 2006.
 [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
            Address Autoconfiguration", RFC 4862, September 2007.

Templin, et al. Informational [Page 11] RFC 5214 ISATAP March 2008

13.2. Informative References

 [RFC2491]  Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6
            over Non-Broadcast Multiple Access (NBMA) networks", RFC
            2491, January 1999.
 [RFC2492]  Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM
            Networks", RFC 2492, January 1999.
 [RFC2529]  Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
            Domains without Explicit Tunnels", RFC 2529, March 1999.
 [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
            via IPv4 Clouds", RFC 3056, February 2001.
 [RFC3756]  Nikander, P., Ed., Kempf, J., and E. Nordmark, "IPv6
            Neighbor Discovery (ND) Trust Models and Threats", RFC
            3756, May 2004.
 [RFC3972]  Aura, T., "Cryptographically Generated Addresses (CGA)",
            RFC 3972, March 2005.
 [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
            More-Specific Routes", RFC 4191, November 2005.
 [RFC4294]  Loughney, J., Ed., "IPv6 Node Requirements", RFC 4294,
            April 2006.
 [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
            Extensions for Stateless Address Autoconfiguration in
            IPv6", RFC 4941, September 2007.

Templin, et al. Informational [Page 12] RFC 5214 ISATAP March 2008

Appendix A. Modified EUI-64 Addresses in the IANA Ethernet Address

           Block
 Modified EUI-64 addresses (Section 2.5.1 and Appendix A of [RFC4291])
 in the IANA Ethernet Address Block are formed by concatenating the
 24-bit IANA OUI (00-00-5E) with a 40-bit extension identifier and
 inverting the "u" bit; i.e., the "u" bit is set to one (1) to
 indicate universal scope and set to zero (0) to indicate local scope.
 Modified EUI-64 addresses have the following appearance in memory
 (bits transmitted right-to-left within octets, octets transmitted
 left-to-right):
 0                       23                                        63
 |        OUI            |            extension identifier         |
 000000ug00000000 01011110xxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx
 When the first two octets of the extension identifier encode the
 hexadecimal value 0xFFFE, the remainder of the extension identifier
 encodes a 24-bit vendor-supplied id as follows:
 0                       23               39                       63
 |        OUI            |     0xFFFE     |   vendor-supplied id   |
 000000ug00000000 0101111011111111 11111110xxxxxxxx xxxxxxxxxxxxxxxx
 When the first octet of the extension identifier encodes the
 hexadecimal value 0xFE, the remainder of the extension identifier
 encodes a 32-bit IPv4 address as follows:
 0                       23      31                                63
 |        OUI            |  0xFE |           IPv4 address          |
 000000ug00000000 0101111011111110 xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx

Templin, et al. Informational [Page 13] RFC 5214 ISATAP March 2008

Authors' Addresses

 Fred L. Templin
 Boeing Phantom Works
 P.O. Box 3707 MC 7L-49
 Seattle, WA  98124
 USA
 EMail: fred.l.templin@boeing.com
 Tim Gleeson
 Cisco Systems K.K.
 Shinjuku Mitsui Building
 2-1-1 Nishishinjuku, Shinjuku-ku
 Tokyo  163-0409
 Japan
 EMail: tgleeson@cisco.com
 Dave Thaler
 Microsoft Corporation
 One Microsoft Way
 Redmond, WA  98052-6399
 US
 Phone: +1 425 703 8835
 EMail: dthaler@microsoft.com

Templin, et al. Informational [Page 14] RFC 5214 ISATAP March 2008

Full Copyright Statement

 Copyright (C) The IETF Trust (2008).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78 and at http://www.rfc-editor.org/copyright.html,
 and except as set forth therein, the authors retain all their rights.
 This document and the information contained herein are provided on an
 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
 THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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.

Intellectual Property

 The IETF takes no position regarding the validity or scope of any
 Intellectual Property Rights or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
 this document or the extent to which any license under such rights
 might or might not be available; nor does it represent that it has
 made any independent effort to identify any such rights.  Information
 on the procedures with respect to rights in RFC documents can be
 found in BCP 78 and BCP 79.
 Copies of IPR disclosures made to the IETF Secretariat and any
 assurances of licenses to be made available, or the result of an
 attempt made to obtain a general license or permission for the use of
 such proprietary rights by implementers or users of this
 specification can be obtained from the IETF on-line IPR repository at
 http://www.ietf.org/ipr.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights that may cover technology that may be required to implement
 this standard.  Please address the information to the IETF at
 ietf-ipr@ietf.org.

Templin, et al. Informational [Page 15]

/data/webs/external/dokuwiki/data/pages/rfc/rfc5214.txt · Last modified: 2008/03/19 19:51 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki