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rfc:rfc8430

Internet Engineering Task Force (IETF) N. Bahadur, Ed. Request for Comments: 8430 Uber Category: Informational S. Kini, Ed. ISSN: 2070-1721

                                                             J. Medved
                                                                 Cisco
                                                        September 2018
                       RIB Information Model

Abstract

 Routing and routing functions in enterprise and carrier networks are
 typically performed by network devices (routers and switches) using a
 Routing Information Base (RIB).  Protocols and configurations push
 data into the RIB, and the RIB manager installs state into the
 hardware for packet forwarding.  This document specifies an
 information model for the RIB to enable defining a standardized data
 model.  The IETF's I2RS WG used this document to design the I2RS RIB
 data model.  This document is being published to record the higher-
 level information model decisions for RIBs so that other developers
 of RIBs may benefit from the design concepts.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Not all documents
 approved by the IESG are candidates for any level of Internet
 Standard; see Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 https://www.rfc-editor.org/info/rfc8430.

Bahadur, et al. Informational [Page 1] RFC 8430 RIB Information Model September 2018

Copyright Notice

 Copyright (c) 2018 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (https://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Bahadur, et al. Informational [Page 2] RFC 8430 RIB Information Model September 2018

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   1.1.  Conventions Used in This Document . . . . . . . . . . . .   6
 2.  RIB Data  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.1.  RIB Definition  . . . . . . . . . . . . . . . . . . . . .   7
   2.2.  Routing Instance  . . . . . . . . . . . . . . . . . . . .   7
   2.3.  Route . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   2.4.  Nexthop . . . . . . . . . . . . . . . . . . . . . . . . .  10
     2.4.1.  Base Nexthops . . . . . . . . . . . . . . . . . . . .  12
     2.4.2.  Derived Nexthops  . . . . . . . . . . . . . . . . . .  14
     2.4.3.  Nexthop Indirection . . . . . . . . . . . . . . . . .  15
 3.  Reading from the RIB  . . . . . . . . . . . . . . . . . . . .  16
 4.  Writing to the RIB  . . . . . . . . . . . . . . . . . . . . .  16
 5.  Notifications . . . . . . . . . . . . . . . . . . . . . . . .  17
 6.  RIB Grammar . . . . . . . . . . . . . . . . . . . . . . . . .  17
   6.1.  Nexthop Grammar Explained . . . . . . . . . . . . . . . .  20
 7.  Using the RIB Grammar . . . . . . . . . . . . . . . . . . . .  20
   7.1.  Using Route Preference  . . . . . . . . . . . . . . . . .  20
   7.2.  Using Different Nexthop Types . . . . . . . . . . . . . .  20
     7.2.1.  Tunnel Nexthops . . . . . . . . . . . . . . . . . . .  21
     7.2.2.  Replication Lists . . . . . . . . . . . . . . . . . .  21
     7.2.3.  Weighted Lists  . . . . . . . . . . . . . . . . . . .  21
     7.2.4.  Protection  . . . . . . . . . . . . . . . . . . . . .  22
     7.2.5.  Nexthop Chains  . . . . . . . . . . . . . . . . . . .  22
     7.2.6.  Lists of Lists  . . . . . . . . . . . . . . . . . . .  23
   7.3.  Performing Multicast  . . . . . . . . . . . . . . . . . .  24
 8.  RIB Operations at Scale . . . . . . . . . . . . . . . . . . .  25
   8.1.  RIB Reads . . . . . . . . . . . . . . . . . . . . . . . .  25
   8.2.  RIB Writes  . . . . . . . . . . . . . . . . . . . . . . .  25
   8.3.  RIB Events and Notifications  . . . . . . . . . . . . . .  25
 9.  Security Considerations . . . . . . . . . . . . . . . . . . .  25
 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26
 11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
   11.1.  Normative References . . . . . . . . . . . . . . . . . .  26
   11.2.  Informative References . . . . . . . . . . . . . . . . .  27
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  28
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  28

Bahadur, et al. Informational [Page 3] RFC 8430 RIB Information Model September 2018

1. Introduction

 Routing and routing functions in enterprise and carrier networks are
 traditionally performed in network devices.  Customarily, routers run
 routing protocols, and the routing protocols (along with static
 configuration information) populate the Routing Information Base
 (RIB) of the router.  The RIB is managed by the RIB manager, and the
 RIB manager provides a northbound interface to its clients (i.e., the
 routing protocols) to insert routes into the RIB.  The RIB manager
 consults the RIB and decides how to program the Forwarding
 Information Base (FIB) of the hardware by interfacing with the FIB
 manager.  The relationship between these entities is shown in
 Figure 1.
       +-------------+        +-------------+
       |RIB Client 1 | ...... |RIB Client N |
       +-------------+        +-------------+
              ^                      ^
              |                      |
              +----------------------+
                         |
                         V
              +---------------------+
              |    RIB Manager      |
              |                     |
              |     +--------+      |
              |     | RIB(s) |      |
              |     +--------+      |
              +---------------------+
                         ^
                         |
        +---------------------------------+
        |                                 |
        V                                 V
 +----------------+               +----------------+
 | FIB Manager 1  |               | FIB Manager M  |
 |   +--------+   |  ..........   |   +--------+   |
 |   | FIB(s) |   |               |   | FIB(s) |   |
 |   +--------+   |               |   +--------+   |
 +----------------+               +----------------+
         Figure 1: RIB Manager, RIB Clients, and FIB Managers
 Routing protocols are inherently distributed in nature, and each
 router makes an independent decision based on the routing data
 received from its peers.  With the advent of newer deployment
 paradigms and the need for specialized applications, there is an
 emerging need to guide the router's routing function [RFC7920].  The

Bahadur, et al. Informational [Page 4] RFC 8430 RIB Information Model September 2018

 traditional network-device RIB population that is protocol based
 suffices for most use cases where distributed network control is
 used.  However, there are use cases that the network operators
 currently address by configuring static routes, policies, and RIB
 import/export rules on the routers.  There is also a growing list of
 use cases in which a network operator might want to program the RIB
 based on data unrelated to just routing (within that network's
 domain).  Programming the RIB could be based on other information
 (such as routing data in the adjacent domain or the load on storage
 and compute) in the given domain.  Or, it could simply be a
 programmatic way of creating on-demand dynamic overlays (e.g., GRE
 tunnels) between compute hosts (without requiring the hosts to run
 traditional routing protocols).  If there was a standardized,
 publicly documented programmatic interface to a RIB, it would enable
 further networking applications that address a variety of use cases
 [RFC7920].
 A programmatic interface to the RIB involves two types of operations:
 reading from the RIB and writing (adding/modifying/deleting) to the
 RIB.
 In order to understand what is in a router's RIB, methods like per-
 protocol SNMP MIBs and screen scraping are used.  These methods are
 not scalable since they are client pull mechanisms and not proactive
 push (from the router) mechanisms.  Screen scraping is error prone
 (since the output format can change) and is vendor dependent.
 Building a RIB from per-protocol MIBs is error prone since the MIB
 data represents protocol data and not the exact information that went
 into the RIB.  Thus, just getting read-only RIB information from a
 router is a hard task.
 Adding content to the RIB from a RIB client can be done today using
 static configuration mechanisms provided by router vendors.  However,
 the mix of what can be modified in the RIB varies from vendor to
 vendor, and the method of configuring it is also vendor dependent.
 This makes it hard for a RIB client to program a multi-vendor network
 in a consistent and vendor-independent way.
 The purpose of this document is to specify an information model for
 the RIB.  Using the information model, one can build a detailed data
 model for the RIB.  That data model could then be used by a RIB
 client to program a network device.  One data model that has been
 based on this document is the I2RS RIB data model [RFC8431].
 The rest of this document is organized as follows.  Section 2 goes
 into the details of what constitutes and can be programmed in a RIB.
 Guidelines for reading and writing the RIB are provided in Sections 3
 and 4, respectively.  Section 5 provides a high-level view of the

Bahadur, et al. Informational [Page 5] RFC 8430 RIB Information Model September 2018

 events and notifications going from a network device to a RIB client
 to update the RIB client on asynchronous events.  The RIB grammar is
 specified in Section 6.  Examples of using the RIB grammar are shown
 in Section 7.  Section 8 covers considerations for performing RIB
 operations at scale.

1.1. Conventions Used in This Document

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
 "OPTIONAL" in this document are to be interpreted as described in
 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
 capitals, as shown here.

2. RIB Data

 This section describes the details of a RIB.  It makes forward
 references to objects in the RIB grammar (see Section 6).  A high-
 level description of the RIB contents is as shown in Figure 2.
 Please note that for ease of representation in ASCII art, this
 drawing shows a single routing instance, a single RIB, and a single
 route.  Subsections of this section describe the logical data nodes
 that should be contained within a RIB.  Sections 3 and 4 describe the
 high-level read and write operations.
                        network-device
                              |
                              | 0..N
                              |
                       routing instance(s)
                        |             |
                        |             |
                  0..N  |             | 0..N
                        |             |
                   interface(s)     RIB(s)
                                      |
                                      |
                                      | 0..N
                                      |
                                    route(s)
                    Figure 2: RIB Information Model

Bahadur, et al. Informational [Page 6] RFC 8430 RIB Information Model September 2018

2.1. RIB Definition

 A RIB, in the context of the RIB information model, is an entity that
 contains routes.  It is identified by its name and is contained
 within a routing instance (see Section 2.2).  A network device MAY
 contain routing instances, and each routing instance MAY contain
 RIBs.  The name MUST be unique within a routing instance.  All routes
 in a given RIB MUST be of the same address family (e.g., IPv4).  Each
 RIB MUST belong to a routing instance.
 A routing instance may contain two or more RIBs of the same address
 family (e.g., IPv6).  A typical case where this can be used is for
 multi-topology routing [RFC4915] [RFC5120].
 Each RIB MAY be associated with an ENABLE_IP_RPF_CHECK attribute that
 enables Reverse Path Forwarding (RPF) checks on all IP routes in that
 RIB.  The RPF check is used to prevent spoofing and limit malicious
 traffic.  For IP packets, the IP source address is looked up and the
 RPF interface(s) associated with the route for that IP source address
 is found.  If the incoming IP packet's interface matches one of the
 RPF interfaces, then the IP packet is forwarded based on its IP
 destination address; otherwise, the IP packet is discarded.

2.2. Routing Instance

 A routing instance, in the context of the RIB information model, is a
 collection of RIBs, interfaces, and routing parameters.  A routing
 instance creates a logical slice of the router.  It allows different
 logical slices across a set of routers to communicate with each
 other.  Layer 3 VPNs, Layer 2 VPNs (L2VPNs), and Virtual Private LAN
 Service (VPLS) can be modeled as routing instances.  Note that
 modeling an L2VPN using a routing instance only models the Layer 3
 (RIB) aspect and does not model any Layer 2 information (like ARP)
 that might be associated with the L2VPN.
 The set of interfaces indicates which interfaces are associated with
 this routing instance.  The RIBs specify how incoming traffic is to
 be forwarded, and the routing parameters control the information in
 the RIBs.  The intersection set of interfaces of two routing
 instances MUST be the null set.  In other words, an interface MUST
 NOT be present in two routing instances.  Thus, a routing instance
 describes the routing information and parameters across a set of
 interfaces.

Bahadur, et al. Informational [Page 7] RFC 8430 RIB Information Model September 2018

 A routing instance MUST contain the following mandatory fields:
 o  INSTANCE_NAME: A routing instance is identified by its name,
    INSTANCE_NAME.  This MUST be unique across all routing instances
    in a given network device.
 o  rib-list: This is the list of RIBs associated with this routing
    instance.  Each routing instance can have multiple RIBs to
    represent routes of different types.  For example, one would put
    IPv4 routes in one RIB and MPLS routes in another RIB.  The list
    of RIBs can be an empty list.
 A routing instance MAY contain the following fields:
 o  interface-list: This represents the list of interfaces associated
    with this routing instance.  The interface list helps constrain
    the boundaries of packet forwarding.  Packets coming in on these
    interfaces are directly associated with the given routing
    instance.  The interface list contains a list of identifiers, with
    each identifier uniquely identifying an interface.
 o  ROUTER_ID: This field identifies the network device in control
    plane interactions with other network devices.  This field is to
    be used if one wants to virtualize a physical router into multiple
    virtual routers.  Each virtual router MUST have a unique
    ROUTER_ID.  A ROUTER_ID MUST be unique across all network devices
    in a given domain.
 A routing instance may be created purely for the purposes of packet
 processing and may not have any interfaces associated with it.  For
 example, an incoming packet in routing instance A might have a
 nexthop of routing instance B, and after packet processing in B, the
 nexthop might be routing instance C.  Thus, routing instance B is not
 associated with any interface.  And, given that this routing instance
 does not do any control-plane interaction with other network devices,
 a ROUTER_ID is also not needed.

2.3. Route

 A route is essentially a match condition and an action following the
 match.  The match condition specifies the kind of route (IPv4, MPLS,
 etc.) and the set of fields to match on.  Figure 3 represents the
 overall contents of a route.  Please note that for ease of depiction
 in ASCII art, only a single instance of the route-attribute, match
 flags, and nexthop is depicted.

Bahadur, et al. Informational [Page 8] RFC 8430 RIB Information Model September 2018

                               route
                               | | |
                     +---------+ | +----------+
                     |           |            |
                0..N |           |            |
       route-attribute         match         nexthop
                                 |
                                 |
                 +-------+-------+-------+--------+
                 |       |       |       |        |
                 |       |       |       |        |
                IPv4    IPv6    MPLS    MAC    Interface
                         Figure 3: Route Model
 This document specifies the following match types:
 o  IPv4: Match on destination and/or source IP address in the IPv4
    header
 o  IPv6: Match on destination and/or source IP address in the IPv6
    header
 o  MPLS: Match on an MPLS label at the top of the MPLS label stack
 o  MAC: Match on Media Access Control (MAC) destination addresses in
    the Ethernet header
 o  Interface: Match on the incoming interface of the packet
 A route MAY be matched on one or more of these match types by policy
 as either an "AND" (to restrict the number of routes) or an "OR" (to
 combine two filters).
 Each route MUST have the following mandatory route-attributes
 associated with it:
 o  ROUTE_PREFERENCE: This is a numerical value that allows for
    comparing routes from different protocols.  Static configuration
    is also considered a protocol for the purpose of this field.  It
    is also known as "administrative distance".  The lower the value,
    the higher the preference.  For example, there can be an OSPF
    route for 192.0.2.1/32 (or IPv6 2001:DB8::1/128) with a preference
    of 5.  If a controller programs a route for 192.0.2.1/32 (or IPv6
    2001:DB8::1/128) with a preference of 2, then the controller's
    route will be preferred by the RIB manager.  Preference should be

Bahadur, et al. Informational [Page 9] RFC 8430 RIB Information Model September 2018

    used to dictate behavior.  For more examples of preference, see
    Section 7.1.
 Each route can have one or more optional route-attributes associated
 with it.
 o  route-vendor-attributes: Vendors can specify vendor-specific
    attributes using this.  The details of this attribute are outside
    the scope of this document.
 Each route has a nexthop associated with it.  Nexthops are described
 in Section 2.4.
 Additional features to match multicast packets were considered (e.g.,
 TTL of the packet to limit the range of a multicast group), but these
 were not added to this information model.  Future RIB information
 models should investigate these multicast features.

2.4. Nexthop

 A nexthop represents an object resulting from a route lookup.  For
 example, if a route lookup results in sending the packet out of a
 given interface, then the nexthop represents that interface.
 Nexthops can be either fully resolved or unresolved.  A resolved
 nexthop has adequate information to send the outgoing packet to the
 destination by forwarding it on an interface to a directly connected
 neighbor.  For example, a nexthop to a point-to-point interface or a
 nexthop to an IP address on an Ethernet interface has the nexthop
 resolved.  An unresolved nexthop is something that requires the RIB
 manager to determine the final resolved nexthop.  For example, a
 nexthop could be an IP address.  The RIB manager would resolve how to
 reach that IP address; for example, is the IP address reachable by
 regular IP forwarding, by an MPLS tunnel, or by both?  If the RIB
 manager cannot resolve the nexthop, then the nexthop remains in an
 unresolved state and is NOT a candidate for installation in the FIB.
 Future RIB events can cause an unresolved nexthop to get resolved
 (e.g., an IP address being advertised by an IGP neighbor).
 Conversely, resolved nexthops can also become unresolved (e.g., in
 the case of a tunnel going down); hence, they would no longer be
 candidates to be installed in the FIB.
 When at least one of a route's nexthops is resolved, then the route
 can be used to forward packets.  Such a route is considered eligible
 to be installed in the FIB and is henceforth referred to as a FIB-
 eligible route.  Conversely, when all the nexthops of a route are
 unresolved, that route can no longer be used to forward packets.
 Such a route is considered ineligible to be installed in the FIB and

Bahadur, et al. Informational [Page 10] RFC 8430 RIB Information Model September 2018

 is henceforth referred to as a FIB-ineligible route.  The RIB
 information model allows a RIB client to program routes whose
 nexthops may be unresolved initially.  Whenever an unresolved nexthop
 gets resolved, the RIB manager will send a notification of the same
 (see Section 5).
 The overall structure and usage of a nexthop is as shown in the
 figure below.  For ease of description using ASCII art, only a single
 instance of any component of the nexthop is shown in Figure 4.
                             route
                               |
                               | 0..N
                               |
                             nexthop <-------------------------------+
                               |                                     |
        +-------+----------------------------+-------------+         |
        |       |              |             |             |         |
        |       |              |             |             |         |
     base   load-balance   protection      replicate     chain       |
        |       |              |             |             |         |
        |       |2..N          |2..N         |2..N         |1..N     |
        |       |              |             |             |         |
        |       |              V             |             |         |
        |       +------------->+<------------+-------------+         |
        |                      |                                     |
        |                      +-------------------------------------+
        |
        +-------------------+
                            |
                            |
                            |
                            |
   +---------------+--------+--------+--------------+----------+
   |               |                 |              |          |
   |               |                 |              |          |
nexthop-id  egress-interface  ip-address     logical-tunnel    |
                                                               |
                                                               |
                        +--------------------------------------+
                        |
     +----------------------+------------------+-------------+
     |                      |                  |             |
     |                      |                  |             |

tunnel-encapsulation tunnel-decapsulation rib-name special-nexthop

                        Figure 4: Nexthop Model

Bahadur, et al. Informational [Page 11] RFC 8430 RIB Information Model September 2018

 This document specifies a very generic, extensible, and recursive
 grammar for nexthops.  A nexthop can be a base nexthop or a derived
 nexthop.  Section 2.4.1 details base nexthops, and Section 2.4.2
 explains various kinds of derived nexthops.  There are certain
 special nexthops, and those are described in Section 2.4.1.1.
 Lastly, Section 2.4.3 delves into nexthop indirection and its use.
 Examples of when and how to use tunnel nexthops and derived nexthops
 are shown in Section 7.2.

2.4.1. Base Nexthops

 At the lowest level, a nexthop can be one of the following:
 o  Identifier: This is an identifier returned by the network device
    representing a nexthop.  This can be used as a way of reusing a
    nexthop when programming derived nexthops.
 o  Interface nexthops: These are nexthops that are pointing to an
    interface.  Various attributes associated with these nexthops are:
  • Egress-interface: This represents a physical, logical, or

virtual interface on the network device. Address resolution

       must not be required on this interface.  This interface may
       belong to any routing instance.
  • IP address: A route lookup on this IP address is done to

determine the egress-interface. Address resolution may be

       required depending on the interface.
       +  An optional rib-name can also be specified to indicate the
          RIB in which the IP address is to be looked up.  One can use
          the rib-name field to direct the packet from one domain into
          another domain.  By default the RIB will be the same as the
          one that route belongs to.
    These attributes can be used in combination as follows:
  • Egress-interface and IP address: This can be used in cases

where, e.g., the IP address is a link-local address.

  • Egress-interface and MAC address: The egress-interface must be

an Ethernet interface. Address resolution is not required for

       this nexthop.

Bahadur, et al. Informational [Page 12] RFC 8430 RIB Information Model September 2018

 o  Tunnel nexthops: These are nexthops that are pointing to a tunnel.
    The types of tunnel nexthops are:
  • tunnel-encapsulation: This can be an encapsulation representing

an IP tunnel, MPLS tunnel, or others as defined in this

       document.  An optional egress-interface can be chained to the
       tunnel-encapsulation to indicate which interface to send the
       packet out on.  The egress-interface is useful when the network
       device contains Ethernet interfaces and one needs to perform
       address resolution for the IP packet.
  • tunnel-decapsulation: This is to specify decapsulating a tunnel

header. After decapsulation, further lookup on the packet can

       be done via chaining it with another nexthop.  The packet can
       also be sent out via an egress-interface directly.
  • logical-tunnel: This can be an MPLS Label Switched Path (LSP)

or a GRE tunnel (or others as defined in this document) that is

       represented by a unique identifier (e.g., name).
 o  rib-name: A nexthop pointing to a RIB.  This indicates that the
    route lookup needs to continue in the specified RIB.  This is a
    way to perform chained lookups.
 Tunnel nexthops allow a RIB client to program static tunnel headers.
 There can be cases where the remote tunnel endpoint does not support
 dynamic signaling (e.g., no LDP support on a host); in those cases,
 the RIB client might want to program the tunnel header on both ends
 of the tunnel.  The tunnel nexthop is kept generic with
 specifications provided for some commonly used tunnels.  It is
 expected that the data model will model these tunnel types with
 complete accuracy.

2.4.1.1. Special Nexthops

 Special nexthops are for performing specific well-defined functions
 (e.g., DISCARD).  The purpose of each of them is explained below:
 o  DISCARD: This indicates that the network device should drop the
    packet and increment a drop counter.
 o  DISCARD_WITH_ERROR: This indicates that the network device should
    drop the packet, increment a drop counter, and send back an
    appropriate error message (like ICMP error).

Bahadur, et al. Informational [Page 13] RFC 8430 RIB Information Model September 2018

 o  RECEIVE: This indicates that the traffic is destined for the
    network device, for example, protocol packets or Operations,
    Administration, and Maintenance (OAM) packets.  All locally
    destined traffic SHOULD be throttled to avoid a denial-of-service
    attack on the router's control plane.  An optional rate limiter
    can be specified to indicate how to throttle traffic destined for
    the control plane.  The description of the rate limiter is outside
    the scope of this document.

2.4.2. Derived Nexthops

 Derived nexthops can be:
 o  weighted lists, which are used for load-balancing;
 o  preference lists, which are used for protection using primary and
    backup;
 o  replication lists, which are lists of nexthops to which to
    replicate a packet;
 o  nexthop chains, which are for chaining multiple operations or
    attaching multiple headers; or
 o  lists of lists, which are a recursive application of the above.
 Nexthop chains (see Section 7.2.5 for usage) are a way to perform
 multiple operations on a packet by logically combining them.  For
 example, one can chain together "decapsulate MPLS header" and "send
 it out a specific egress-interface".  Chains can be used to specify
 multiple headers over a packet before a packet is forwarded.  One
 simple example is that of MPLS over GRE, wherein the packet has an
 inner MPLS header followed by a GRE header followed by an IP header.
 The outermost IP header is decided by the network device, whereas the
 MPLS header or GRE header is specified by the controller.  Not every
 network device will be able to support all kinds of nexthop chains
 and an arbitrary number of headers chained together.  The RIB data
 model SHOULD provide a way to expose a nexthop chaining capability
 supported by a given network device.
 It is expected that all network devices will have a limit on how many
 levels of lookup can be performed, and not all hardware will be able
 to support all kinds of nexthops.  RIB capability negotiation becomes
 very important for this reason, and a RIB data model MUST specify a
 way for a RIB client to learn about the network device's
 capabilities.

Bahadur, et al. Informational [Page 14] RFC 8430 RIB Information Model September 2018

2.4.2.1. Nexthop List Attributes

 For nexthops that are of the form of a list(s), attributes can be
 associated with each member of the list to indicate the role of an
 individual member of the list.  Two attributes are specified:
 o  NEXTHOP_PREFERENCE: This is used for protection schemes.  It is an
    integer value between 1 and 99.  A lower value indicates higher
    preference.  To download a primary/standby pair to the FIB, the
    nexthops that are resolved and have the two highest preferences
    are selected.  Each <NEXTHOP_PREFERENCE> should have a unique
    value within a <nexthop-protection> (see Section 6).
 o  NEXTHOP_LB_WEIGHT: This is used for load-balancing.  Each list
    member MUST be assigned a weight between 1 and 99.  The weight
    determines the proportion of traffic to be sent over a nexthop
    used for forwarding as a ratio of the weight of this nexthop
    divided by the weights of all the nexthops of this route that are
    used for forwarding.  To perform equal load-balancing, one MAY
    specify a weight of "0" for all the member nexthops.  The value
    "0" is reserved for equal load-balancing and, if applied, MUST be
    applied to all member nexthops.  Note that a weight of 0 is
    special because of historical reasons.

2.4.3. Nexthop Indirection

 Nexthops can be identified by an identifier to create a level of
 indirection.  The identifier is set by the RIB manager and returned
 to the RIB client on request.
 One example of usage of indirection is a nexthop that points to
 another network device (e.g., a BGP peer).  The returned nexthop
 identifier can then be used for programming routes to point to the
 this nexthop.  Given that the RIB manager has created an indirection
 using the nexthop identifier, if the transport path to the network
 device (BGP peer) changes, that change in path will be seamless to
 the RIB client and all routes that point to that network device will
 automatically start going over the new transport path.  Nexthop
 indirection using identifiers could be applied to not only unicast
 nexthops but also nexthops that contain chains and nested nexthops.
 See Section 2.4.2 for examples.

Bahadur, et al. Informational [Page 15] RFC 8430 RIB Information Model September 2018

3. Reading from the RIB

 A RIB data model MUST allow a RIB client to read entries for RIBs
 created by that entity.  The network device administrator MAY allow
 reading of other RIBs by a RIB client through access lists on the
 network device.  The details of access lists are outside the scope of
 this document.
 The data model MUST support a full read of the RIB and subsequent
 incremental reads of changes to the RIB.  When sending data to a RIB
 client, the RIB manager SHOULD try to send all dependencies of an
 object prior to sending that object.

4. Writing to the RIB

 A RIB data model MUST allow a RIB client to write entries for RIBs
 created by that entity.  The network device administrator MAY allow
 writes to other RIBs by a RIB client through access lists on the
 network device.  The details of access lists are outside the scope of
 this document.
 When writing an object to a RIB, the RIB client SHOULD try to write
 all dependencies of the object prior to sending that object.  The
 data model SHOULD support requesting identifiers for nexthops and
 collecting the identifiers back in the response.
 Route programming in the RIB MUST result in a return code that
 contains the following attributes:
 o  Installed: Yes/No (indicates whether the route got installed in
    the FIB)
 o  Active: Yes/No (indicates whether a route is fully resolved and is
    a candidate for selection)
 o  Reason: E.g., "Not authorized"
 The data model MUST specify which objects can be modified.  An object
 that can be modified is one whose contents can be changed without
 having to change objects that depend on it and without affecting any
 data forwarding.  To change a non-modifiable object, one will need to
 create a new object and delete the old one.  For example, routes that
 use a nexthop that is identified by a nexthop identifier should be
 unaffected when the contents of that nexthop changes.

Bahadur, et al. Informational [Page 16] RFC 8430 RIB Information Model September 2018

5. Notifications

 Asynchronous notifications are sent by the network device's RIB
 manager to a RIB client when some event occurs on the network device.
 A RIB data model MUST support sending asynchronous notifications.  A
 brief list of suggested notifications is as below:
 o  Route change notification (with a return code as specified in
    Section 4)
 o  Nexthop resolution status (resolved/unresolved) notification

6. RIB Grammar

 This section specifies the RIB information model in Routing Backus-
 Naur Form (rBNF) [RFC5511].  This grammar is intended to help the
 reader better understand Section 2 in order to derive a data model.

<routing-instance> ::= <INSTANCE_NAME>

                      [<interface-list>] <rib-list>
                      [<ROUTER_ID>]

<interface-list> ::= (<INTERFACE_IDENTIFIER> …)

<rib-list> ::= (<rib> …) <rib> ::= <rib-name> <address-family>

                   [<route> ... ]
                   [ENABLE_IP_RPF_CHECK]

<address-family> ::= <IPV4_ADDRESS_FAMILY> | <IPV6_ADDRESS_FAMILY> |

                    <MPLS_ADDRESS_FAMILY> | <IEEE_MAC_ADDRESS_FAMILY>

<route> ::= <match> <nexthop>

           [<route-attributes>]
           [<route-vendor-attributes>]

<match> ::= <IPV4> <ipv4-route> | <IPV6> <ipv6-route> |

           <MPLS> <MPLS_LABEL> | <IEEE_MAC> <MAC_ADDRESS> |
           <INTERFACE> <INTERFACE_IDENTIFIER>

<route-type> ::= <IPV4> | <IPV6> | <MPLS> | <IEEE_MAC> | <INTERFACE>

Bahadur, et al. Informational [Page 17] RFC 8430 RIB Information Model September 2018

<ipv4-route> ::= <ip-route-type>

                (<destination-ipv4-address> | <source-ipv4-address> |
                 (<destination-ipv4-address> <source-ipv4-address>))

<destination-ipv4-address> ::= <ipv4-prefix> <source-ipv4-address> ::= <ipv4-prefix> <ipv4-prefix> ::= <IPV4_ADDRESS> <IPV4_PREFIX_LENGTH>

<ipv6-route> ::= <ip-route-type>

                (<destination-ipv6-address> | <source-ipv6-address> |
                 (<destination-ipv6-address> <source-ipv6-address>))

<destination-ipv6-address> ::= <ipv6-prefix> <source-ipv6-address> ::= <ipv6-prefix> <ipv6-prefix> ::= <IPV6_ADDRESS> <IPV6_PREFIX_LENGTH> <ip-route-type> ::= <SRC> | <DEST> | <DEST_SRC>

<route-attributes> ::= <ROUTE_PREFERENCE> [<LOCAL_ONLY>]

                      [<address-family-route-attributes>]

<address-family-route-attributes> ::= <ip-route-attributes> |

                                     <mpls-route-attributes> |
                                     <ethernet-route-attributes>

<ip-route-attributes> ::= <> <mpls-route-attributes> ::= <> <ethernet-route-attributes> ::= <> <route-vendor-attributes> ::= <>

<nexthop> ::= <nexthop-base> |

             (<NEXTHOP_LOAD_BALANCE> <nexthop-lb>) |
             (<NEXTHOP_PROTECTION> <nexthop-protection>) |
             (<NEXTHOP_REPLICATE> <nexthop-replicate>) |
             <nexthop-chain>

<nexthop-base> ::= <NEXTHOP_ID> |

                  <nexthop-special> |
                  <egress-interface> |
                  <ipv4-address> | <ipv6-address> |
                  (<egress-interface>
                      (<ipv4-address> | <ipv6-address>)) |
                  (<egress-interface> <IEEE_MAC_ADDRESS>) |
                  <tunnel-encapsulation> | <tunnel-decapsulation> |
                  <logical-tunnel> |
                  <rib-name>

<egress-interface> ::= <INTERFACE_IDENTIFIER>

Bahadur, et al. Informational [Page 18] RFC 8430 RIB Information Model September 2018

<nexthop-special> ::= <DISCARD> | <DISCARD_WITH_ERROR> |

                     (<RECEIVE> [<COS_VALUE>])

<nexthop-lb> ::= <NEXTHOP_LB_WEIGHT> <nexthop>

                (<NEXTHOP_LB_WEIGHT> <nexthop) ...

<nexthop-protection> = <NEXTHOP_PREFERENCE> <nexthop>

                     (<NEXTHOP_PREFERENCE> <nexthop>)...

<nexthop-replicate> ::= <nexthop> <nexthop> …

<nexthop-chain> ::= <nexthop> …

<logical-tunnel> ::= <tunnel-type> <TUNNEL_NAME> <tunnel-type> ::= <IPV4> | <IPV6> | <MPLS> | <GRE> | <VxLAN> | <NVGRE>

<tunnel-encapsulation> ::= (<IPV4> <ipv4-header>) |

                          (<IPV6> <ipv6-header>) |
                          (<MPLS> <mpls-header>) |
                          (<GRE> <gre-header>) |
                          (<VXLAN> <vxlan-header>) |
                          (<NVGRE> <nvgre-header>)

<ipv4-header> ::= <SOURCE_IPv4_ADDRESS> <DESTINATION_IPv4_ADDRESS>

                 <PROTOCOL> [<TTL>] [<DSCP>]

<ipv6-header> ::= <SOURCE_IPV6_ADDRESS> <DESTINATION_IPV6_ADDRESS>

                 <NEXT_HEADER> [<TRAFFIC_CLASS>]
                 [<FLOW_LABEL>] [<HOP_LIMIT>]

<mpls-header> ::= (<mpls-label-operation> …) <mpls-label-operation> ::= (<MPLS_PUSH> <MPLS_LABEL> [<S_BIT>]

                                       [<TOS_VALUE>] [<TTL_VALUE>]) |
                          (<MPLS_SWAP> <IN_LABEL> <OUT_LABEL>
                                      [<TTL_ACTION>])

<gre-header> ::= <GRE_IP_DESTINATION> <GRE_PROTOCOL_TYPE> [<GRE_KEY>] <vxlan-header> ::= (<ipv4-header> | <ipv6-header>)

                  [<VXLAN_IDENTIFIER>]

<nvgre-header> ::= (<ipv4-header> | <ipv6-header>)

                  <VIRTUAL_SUBNET_ID>
                  [<FLOW_ID>]

Bahadur, et al. Informational [Page 19] RFC 8430 RIB Information Model September 2018

<tunnel-decapsulation> ::= 1)

1)
<IPV4> <IPV4_DECAP> [<TTL_ACTION>]) |
                          (<IPV6> <IPV6_DECAP> [<HOP_LIMIT_ACTION>]) |
                          (<MPLS> <MPLS_POP> [<TTL_ACTION>]))
                      Figure 5: RIB rBNF Grammar
6.1. Nexthop Grammar Explained
 A nexthop is used to specify the next network element to forward the
 traffic to.  It is also used to specify how the traffic should be
 load-balanced, protected using preference, or multicast using
 replication.  This is explicitly specified in the grammar.  The
 nexthop has recursion built in to address complex use cases like the
 one defined in Section 7.2.6.
7. Using the RIB Grammar
 The RIB grammar is very generic and covers a variety of features.
 This section provides examples on using objects in the RIB grammar
 and examples to program certain use cases.
7.1. Using Route Preference
 Using route preference, a client can preinstall alternate paths in
 the network.  For example, if OSPF has a route preference of 10, then
 another client can install a route with a route preference of 20 to
 the same destination.  The OSPF route will get precedence and will
 get installed in the FIB.  When the OSPF route is withdrawn, the
 alternate path will get installed in the FIB.
 Route preference can also be used to prevent denial-of-service
 attacks by installing routes with the best preference, which either
 drops the offending traffic or routes it to some monitoring/analysis
 station.  Since the routes are installed with the best preference,
 they will supersede any route installed by any other protocol.
7.2. Using Different Nexthop Types
 The RIB grammar allows one to create a variety of nexthops.  This
 section describes uses for certain types of nexthops.
Bahadur, et al. Informational [Page 20] RFC 8430 RIB Information Model September 2018 7.2.1. Tunnel Nexthops
 A tunnel nexthop points to a tunnel of some kind.  Traffic that goes
 over the tunnel gets encapsulated with the tunnel-encapsulation.
 Tunnel nexthops are useful for abstracting out details of the network
 by having the traffic seamlessly route between network edges.  At the
 end of a tunnel, the tunnel will get decapsulated.  Thus, the grammar
 supports two kinds of operations: one for encapsulation and another
 for decapsulation.
7.2.2. Replication Lists
 One can create a replication list for replicating traffic to multiple
 destinations.  The destinations, in turn, could be derived nexthops
 in themselves (at a level supported by the network device); point to
 multipoint and broadcast are examples that involve replication.
 A replication list (at the simplest level) can be represented as:
 <nexthop> ::= <NEXTHOP_REPLICATE> <nexthop> [ <nexthop> ... ]
 The above can be derived from the grammar as follows:
 <nexthop> ::= <nexthop-replicate>
 <nexthop> ::= <NEXTHOP_REPLICATE> <nexthop> <nexthop> ...
7.2.3. Weighted Lists
 A weighted list is used to load-balance traffic among a set of
 nexthops.  From a modeling perspective, a weighted list is very
 similar to a replication list, with the difference that each member
 nexthop MUST have a NEXTHOP_LB_WEIGHT associated with it.
 A weighted list (at the simplest level) can be represented as:
 <nexthop> ::= <NEXTHOP_LOAD_BALANCE> (<nexthop> <NEXTHOP_LB_WEIGHT>)
                    [(<nexthop> <NEXTHOP_LB_WEIGHT>)... ]
 The above can be derived from the grammar as follows:
 <nexthop> ::= <nexthop-lb>
 <nexthop> ::= <NEXTHOP_LOAD_BALANCE>
                 <NEXTHOP_LB_WEIGHT> <nexthop>
                 (<NEXTHOP_LB_WEIGHT> <nexthop>) ...
 <nexthop> ::= <NEXTHOP_LOAD_BALANCE> (<NEXTHOP_LB_WEIGHT> <nexthop>)
                 (<NEXTHOP_LB_WEIGHT> <nexthop>) ...
Bahadur, et al. Informational [Page 21] RFC 8430 RIB Information Model September 2018 7.2.4. Protection
 A primary/backup protection can be represented as:
 <nexthop> ::= <NEXTHOP_PROTECTION> <1> <interface-primary>
                                    <2> <interface-backup>)
 The above can be derived from the grammar as follows:
<nexthop> ::= <nexthop-protection> <nexthop> ::= <NEXTHOP_PROTECTION> (<NEXTHOP_PREFERENCE> <nexthop>
                    (<NEXTHOP_PREFERENCE> <nexthop>)...)
<nexthop> ::= <NEXTHOP_PROTECTION> (<NEXTHOP_PREFERENCE> <nexthop>
                    (<NEXTHOP_PREFERENCE> <nexthop>))
<nexthop> ::= <NEXTHOP_PROTECTION> ((<NEXTHOP_PREFERENCE> <nexthop-base>
                    (<NEXTHOP_PREFERENCE> <nexthop-base>))
<nexthop> ::= <NEXTHOP_PROTECTION> (<1> <interface-primary>
                    (<2> <interface-backup>))
 Traffic can be load-balanced among multiple primary nexthops and a
 single backup.  In such a case, the nexthop will look like:
 <nexthop> ::= <NEXTHOP_PROTECTION> (<1>
               (<NEXTHOP_LOAD_BALANCE>
                (<NEXTHOP_LB_WEIGHT> <nexthop-base>
                (<NEXTHOP_LB_WEIGHT> <nexthop-base>) ...))
                 <2> <nexthop-base>)
 A backup can also have another backup.  In such a case, the list will
 look like:
 <nexthop> ::= <NEXTHOP_PROTECTION> (<1> <nexthop>
               <2> <NEXTHOP_PROTECTION>(<1> <nexthop> <2> <nexthop>))
7.2.5. Nexthop Chains
 A nexthop chain is a way to perform multiple operations on a packet
 by logically combining them.  For example, when a VPN packet comes on
 the WAN interface and has to be forwarded to the correct VPN
 interface, one needs to pop the VPN label before sending the packet
 out.  Using a nexthop chain, one can chain together "pop MPLS header"
 and "send it out a specific egress-interface".
Bahadur, et al. Informational [Page 22] RFC 8430 RIB Information Model September 2018
 The above example can be derived from the grammar as follows:
 <nexthop-chain> ::= <nexthop> <nexthop>
 <nexthop-chain> ::= <nexthop-base> <nexthop-base>
 <nexthop-chain> ::= <tunnel-decapsulation> <egress-interface>
 <nexthop-chain> ::= (<MPLS> <MPLS_POP>) <interface-outgoing>
 Elements in a nexthop chain are evaluated left to right.
 A nexthop chain can also be used to put one or more headers on an
 outgoing packet.  One example is a pseudowire, which is MPLS over
 some transport (MPLS or GRE, for instance).  Another example is
 Virtual eXtensible Local Area Network (VXLAN) over IP.  A nexthop
 chain thus allows a RIB client to break up the programming of the
 nexthop into independent pieces (one per encapsulation).
 A simple example of MPLS over GRE can be represented as follows:
 <nexthop-chain> ::= (<MPLS> <mpls-header>) (<GRE> <gre-header>)
                     <interface-outgoing>
 The above can be derived from the grammar as follows:
 <nexthop-chain> ::= <nexthop> <nexthop> <nexthop>
 <nexthop-chain> ::= <nexthop-base> <nexthop-base> <nexthop-base>
 <nexthop-chain> ::= <tunnel-encapsulation> <tunnel-encapsulation>
                     <egress-interface>
 <nexthop-chain> ::= (<MPLS> <mpls-header>) (<GRE> <gre-header>)
                     <interface-outgoing>
7.2.6. Lists of Lists
 Lists of lists is a derived construct.  One example of usage of such
 a construct is to replicate traffic to multiple destinations with
 load-balancing.  In other words, for each branch of the replication
 tree, there are multiple interfaces on which traffic needs to be
 load-balanced.  So, the outer list is a replication list for
 multicast and the inner lists are weighted lists for load-balancing.
 Let's take an example of a network element that has to replicate
 traffic to two other network elements.  Traffic to the first network
 element should be load-balanced equally over two interfaces:
 outgoing-1-1 and outgoing-1-2.  Traffic to the second network element
 should be load-balanced over three interfaces: outgoing-2-1,
 outgoing-2-2, and outgoing-2-3 (in the ratio 20:20:60).
Bahadur, et al. Informational [Page 23] RFC 8430 RIB Information Model September 2018
 This can be derived from the grammar as follows:
<nexthop> ::= <nexthop-replicate> <nexthop> ::= <NEXTHOP_REPLICATE> (<nexthop> <nexthop>…) <nexthop> ::= <NEXTHOP_REPLICATE> (<nexthop> <nexthop>) <nexthop> ::= <NEXTHOP_REPLICATE> ((<NEXTHOP_LOAD_BALANCE> <nexthop-lb>)
            (<NEXTHOP_LOAD_BALANCE> <nexthop-lb>))
<nexthop> ::= <NEXTHOP_REPLICATE> ((<NEXTHOP_LOAD_BALANCE>
            (<NEXTHOP_LB_WEIGHT> <nexthop>
            (<NEXTHOP_LB_WEIGHT> <nexthop>) ...))
             ((<NEXTHOP_LOAD_BALANCE>
              (<NEXTHOP_LB_WEIGHT> <nexthop>
              (<NEXTHOP_LB_WEIGHT> <nexthop>) ...))
<nexthop> ::= <NEXTHOP_REPLICATE> ((<NEXTHOP_LOAD_BALANCE>
            (<NEXTHOP_LB_WEIGHT> <nexthop>
             (<NEXTHOP_LB_WEIGHT> <nexthop>)))
              ((<NEXTHOP_LOAD_BALANCE>
              (<NEXTHOP_LB_WEIGHT> <nexthop>
              (<NEXTHOP_LB_WEIGHT> <nexthop>)
              (<NEXTHOP_LB_WEIGHT> <nexthop>)))
<nexthop> ::= <NEXTHOP_REPLICATE> ((<NEXTHOP_LOAD_BALANCE>
             (<NEXTHOP_LB_WEIGHT> <nexthop>)
             (<NEXTHOP_LB_WEIGHT> <nexthop>)))
             ((<NEXTHOP_LOAD_BALANCE>
             (<NEXTHOP_LB_WEIGHT> <nexthop>)
             (<NEXTHOP_LB_WEIGHT> <nexthop>)
             (<NEXTHOP_LB_WEIGHT> <nexthop>)))
<nexthop> ::= <NEXTHOP_REPLICATE>
             ((<NEXTHOP_LOAD_BALANCE>
               (50 <outgoing-1-1>)
               (50 <outgoing-1-2>)))
              ((<NEXTHOP_LOAD_BALANCE>
                (20 <outgoing-2-1>)
                (20 <outgoing-2-2>)
                (60 <outgoing-2-3>)))
7.3. Performing Multicast
 IP multicast involves matching a packet on (S,G) or (*,G), where both
 S (Source) and G (Group) are IP prefixes.  Following the match, the
 packet is replicated to one or more recipients.  How the recipients
 subscribe to the multicast group is outside the scope of this
 document.
 In PIM-based multicast, the packets are IP forwarded on an IP
 multicast tree.  The downstream nodes on each point in the multicast
 tree are one or more IP addresses.  These can be represented as a
 replication list (see Section 7.2.2).
Bahadur, et al. Informational [Page 24] RFC 8430 RIB Information Model September 2018
 In MPLS-based multicast, the packets are forwarded on a Point-to-
 Multipoint (P2MP) LSP.  The nexthop for a P2MP LSP can be represented
 in the nexthop grammar as a <logical-tunnel> (P2MP LSP identifier) or
 a replication list (see Section 7.2.2) of <tunnel-encapsulation>,
 with each tunnel-encapsulation representing a single MPLS downstream
 nexthop.
8. RIB Operations at Scale
 This section discusses the scale requirements for a RIB data model.
 The RIB data model should be able to handle a large scale of
 operations to enable deployment of RIB applications in large
 networks.
8.1. RIB Reads
 Bulking (grouping of multiple objects in a single message) MUST be
 supported when a network device sends RIB data to a RIB client.
 Similarly, the data model MUST enable a RIB client to request data in
 bulk from a network device.
8.2. RIB Writes
 Bulking (grouping of multiple write operations in a single message)
 MUST be supported when a RIB client wants to write to the RIB.  The
 response from the network device MUST include a return-code for each
 write operation in the bulk message.
8.3. RIB Events and Notifications
 There can be cases where a single network event results in multiple
 events and/or notifications from the network device to a RIB client.
 On the other hand, due to timing of multiple things happening at the
 same time, a network device might have to send multiple events and/or
 notifications to a RIB client.  The network-device-originated event/
 notification message MUST support the bulking of multiple events and
 notifications in a single message.
9. Security Considerations
 The information model specified in this document defines a schema for
 data models that are designed to be accessed via network management
 protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040].  The
 lowest NETCONF layer is the secure transport layer, and the
 mandatory-to-implement secure transport is Secure Shell (SSH)
 [RFC6242].  The lowest RESTCONF layer is HTTPS, and the mandatory-to-
 implement secure transport is TLS [RFC8446].
Bahadur, et al. Informational [Page 25] RFC 8430 RIB Information Model September 2018
 The NETCONF access control model [RFC8341] provides the means to
 restrict access for particular NETCONF or RESTCONF users to a
 preconfigured subset of all available NETCONF or RESTCONF protocol
 operations and content.
 The RIB information model specifies read and write operations to
 network devices.  These network devices might be considered sensitive
 or vulnerable in some network environments.  Write operations to
 these network devices without proper protection can have a negative
 effect on network operations.  Due to this factor, it is recommended
 that data models also consider the following in their design:
 o  Require utilization of the authentication and authorization
    features of the NETCONF or RESTCONF suite of protocols.
 o  Augment the limits on how much data can be written or updated by a
    remote entity built to include enough protection for a RIB data
    model.
 o  Expose the specific RIB data model implemented via NETCONF/
    RESTCONF data models.
10. IANA Considerations
 This document has no IANA actions.
11. References 11.1. Normative References
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <https://www.rfc-editor.org/info/rfc2119>.
 [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
            and A. Bierman, Ed., "Network Configuration Protocol
            (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
            <https://www.rfc-editor.org/info/rfc6241>.
 [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
            Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
            <https://www.rfc-editor.org/info/rfc6242>.
 [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
            Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
            <https://www.rfc-editor.org/info/rfc8040>.
Bahadur, et al. Informational [Page 26] RFC 8430 RIB Information Model September 2018
 [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
            2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
            May 2017, <https://www.rfc-editor.org/info/rfc8174>.
 [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
            Access Control Model", STD 91, RFC 8341,
            DOI 10.17487/RFC8341, March 2018,
            <https://www.rfc-editor.org/info/rfc8341>.
 [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
            Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
            <https://www.rfc-editor.org/info/rfc8446>.
11.2. Informative References
 [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
            Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
            RFC 4915, DOI 10.17487/RFC4915, June 2007,
            <https://www.rfc-editor.org/info/rfc4915>.
 [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
            Topology (MT) Routing in Intermediate System to
            Intermediate Systems (IS-ISs)", RFC 5120,
            DOI 10.17487/RFC5120, February 2008,
            <https://www.rfc-editor.org/info/rfc5120>.
 [RFC5511]  Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
            Used to Form Encoding Rules in Various Routing Protocol
            Specifications", RFC 5511, DOI 10.17487/RFC5511, April
            2009, <https://www.rfc-editor.org/info/rfc5511>.
 [RFC7920]  Atlas, A., Ed., Nadeau, T., Ed., and D. Ward, "Problem
            Statement for the Interface to the Routing System",
            RFC 7920, DOI 10.17487/RFC7920, June 2016,
            <https://www.rfc-editor.org/info/rfc7920>.
 [RFC8431]  Wang, L., Chen, M., Dass, A., Ananthakrishnan, H., Kini,
            S., and N. Bahadur, "A YANG Data Model for the Routing
            Information Base (RIB)", RFC 8431, DOI 10.17487/RFC8431,
            September 2018, <http://www.rfc-editor.org/info/rfc8431>.
Bahadur, et al. Informational [Page 27] RFC 8430 RIB Information Model September 2018 Acknowledgements
 The authors would like to thank Ron Folkes, Jeffrey Zhang, the WG
 co-Chairs, and reviewers for their comments and suggestions on this
 document.  The following people contributed to the design of the RIB
 information model as part of the I2RS Interim meeting in April 2013:
 Wes George, Chris Liljenstolpe, Jeff Tantsura, Susan Hares, and
 Fabian Schneider.
Authors' Addresses
 Nitin Bahadur (editor)
 Uber
 900 Arastradero Rd
 Palo Alto, CA  94304
 United States of America
 Email: nitin_bahadur@yahoo.com
 Sriganesh Kini (editor)
 Email: sriganeshkini@gmail.com
 Jan Medved
 Cisco
 Email: jmedved@cisco.com
Bahadur, et al. Informational [Page 28]
/data/webs/external/dokuwiki/data/pages/rfc/rfc8430.txt · Last modified: 2018/09/26 16:35 by 127.0.0.1

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