]> LabN Consulting, L.L.C.

301 Midenhall Way Cary NC United States of America 27513 acee.ietf@gmail.com

Futurewei Technologies

2330 Central Expressway Santa Clara CA 95050 United States of America yingzhen.qu@futurewei.com

rtg rtgwg configuration IPv6 Router Advertisements NETCONF RESTCONF YANG Routing RIB A Routing Information Base (RIB) is a list of routes and their corresponding administrative data and operational state. RFC 8349 defines the basic building blocks for the RIB data model, and this model augments it to support multiple next hops (aka paths) for each route as well as additional attributes.

Introduction This document defines a YANG data model that extends the RIB data model defined in the ietf-routing YANG module with more route attributes. A RIB is a collection of routes with attributes controlled and manipulated by control plane protocols. Each RIB contains only routes of one address family . Within a protocol, routes are selected based on the metrics in use by that protocol, and the protocol installs the routes to the RIB. The RIB selects the preferred or active route by comparing the route preference (aka administrative distance) of the candidate routes installed by different protocols. The module defined in this document extends the RIB to support more route attributes, such as multiple next hops, route metrics, and administrative tags. The YANG modules defined and discussed in this document conform to the Network Management Datastore Architecture (NMDA) .

Terminology and Notation The following terms are defined in :

• configuration
• system state
• operational state

The following terms are defined in :

• action
• augment
• container
• container with presence
• data model
• data node
• leaf
• list
• mandatory node
• module
• schema tree

The following term is defined in :

• RIB

Tree Diagrams Tree diagrams used in this document follow the notation defined in .

Prefixes in Data Node Names In this document, names of data nodes, actions, and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in . Prefixes and Corresponding YANG Modules

Prefix	YANG Module	Reference
if	ietf-interfaces
rt	ietf-routing
v4ur	ietf-ipv4-unicast-routing
v6ur	ietf-ipv6-unicast-routing
inet	ietf-inet-types
ospf	ietf-ospf
isis	ietf-isis

Design of the Model The YANG module defined in this document augments the ietf-routing, ietf-ipv4-unicast-routing, and ietf-ipv6-unicast-routing YANG modules defined in , which provide a basis for routing system data model development. Together with the ietf-routing YANG module and other YANG modules defined in , a generic RIB YANG data model is defined herein to implement and monitor a RIB. The modules in also define the basic configuration and operational state for both IPv4 and IPv6 static routes. This document provides augmentations for static routes to support multiple next hops and more next-hop attributes.

Tags and Preferences Individual route tags are supported at both the route and next-hop level. A preference per next hop is also supported for selection of the most preferred reachable static route. The following tree snapshot shows tag and preference entries that augment static IPv4 unicast route and IPv6 unicast route next hops.

Repair Path The IP Fast Reroute (IPFRR) calculation by routing protocol precomputes repair paths , and the repair paths are installed in the RIB. Each route next hop in the RIB is augmented with a repair path and is shown in the following tree snapshot.

RIB Model Tree The ietf-routing.yang tree with the augmentations herein is included in . The meanings of the symbols can be found in .

RIB Extension YANG Module This YANG module references , , , , , and . WG List: Author: Acee Lindem Author: Yingzhen Qu "; description "This YANG module extends the RIB defined in the ietf-routing YANG module with additional route attributes. This YANG module conforms to the Network Management Datastore Architecture (NMDA) as described in RFC 8342. Copyright (c) 2023 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC 9403; see the RFC itself for full legal notices."; revision 2023-11-20 { description "Initial version."; reference "RFC 9403: A YANG Data Model for RIB Extensions"; } /* Groupings */ grouping rib-statistics { description "Statistics grouping used for RIB augmentation."; container statistics { config false; description "Container for RIB statistics."; leaf total-routes { type uint32; description "Total number of routes in the RIB."; } leaf total-active-routes { type uint32; description "Total number of active routes in the RIB. An active route is the route that is preferred over other routes to the same destination prefix."; } leaf total-route-memory { type uint64; units "bytes"; description "Total memory for all routes in the RIB."; } list protocol-statistics { description "RIB statistics for routing protocols installing routes in the RIB."; leaf protocol { type identityref { base rt:routing-protocol; } description "Routing protocol installing routes in the RIB."; } leaf routes { type uint32; description "Total number of routes in the RIB for the routing protocol identified by the 'protocol' entry."; } leaf active-routes { type uint32; description "Total number of active routes in the RIB for the routing protocol identified by the 'protocol' entry. An active route is preferred over other routes to the same destination prefix."; } leaf route-memory { type uint64; units "bytes"; description "Total memory for all routes in the RIB for the routing protocol identified by the 'protocol' entry."; } } } } grouping repair-path { description "Grouping for the IP Fast Reroute (IPFRR) repair path."; container repair-path { description "IPFRR next-hop repair path."; leaf outgoing-interface { type if:interface-state-ref; description "Name of the outgoing interface."; } leaf next-hop-address { type inet:ip-address-no-zone; description "IP address of the next hop."; } leaf metric { type uint32; description "The metric for the repair path. While the reroute repair is local and the metric is not advertised externally, the metric for the repair path is useful for troubleshooting purposes."; } reference "RFC 5714: IP Fast Reroute Framework"; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:static-routes/v4ur:ipv4/" + "v4ur:route/v4ur:next-hop/v4ur:next-hop-options/" + "v4ur:simple-next-hop" { description "Augment 'simple-next-hop' case in IPv4 unicast route."; leaf preference { type uint32; default "1"; description "The preference is used to select among multiple static routes. Routes with a lower next-hop preference value are preferred, and equal-preference routes result in Equal-Cost Multipath (ECMP) static routes."; } leaf tag { type uint32; default "0"; description "The tag is a 32-bit opaque value associated with the route that can be used for policy decisions such as advertisement and filtering of the route."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:static-routes/v4ur:ipv4/" + "v4ur:route/v4ur:next-hop/v4ur:next-hop-options/" + "v4ur:next-hop-list/v4ur:next-hop-list/v4ur:next-hop" { description "Augment static route configuration 'next-hop-list'."; leaf preference { type uint32; default "1"; description "The preference is used to select among multiple static routes. Routes with a lower next-hop preference value are preferred, and equal-preference routes result in ECMP static routes."; } leaf tag { type uint32; default "0"; description "The tag is a 32-bit opaque value associated with the route that can be used for policy decisions such as advertisement and filtering of the route."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:static-routes/v6ur:ipv6/" + "v6ur:route/v6ur:next-hop/v6ur:next-hop-options/" + "v6ur:simple-next-hop" { description "Augment 'simple-next-hop' case in IPv6 unicast route."; leaf preference { type uint32; default "1"; description "The preference is used to select among multiple static routes. Routes with a lower next-hop preference value are preferred, and equal-preference routes result in ECMP static routes."; } leaf tag { type uint32; default "0"; description "The tag is a 32-bit opaque value associated with the route that can be used for policy decisions such as advertisement and filtering of the route."; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/rt:static-routes/v6ur:ipv6/" + "v6ur:route/v6ur:next-hop/v6ur:next-hop-options/" + "v6ur:next-hop-list/v6ur:next-hop-list/v6ur:next-hop" { description "Augment static route configuration 'next-hop-list'."; leaf preference { type uint32; default "1"; description "The preference is used to select among multiple static routes. Routes with a lower next-hop preference value are preferred, and equal-preference routes result in ECMP static routes."; } leaf tag { type uint32; default "0"; description "The tag is a 32-bit opaque value associated with the route that can be used for policy decisions such as advertisement and filtering of the route."; } } augment "/rt:routing/rt:ribs/rt:rib" { description "Augment a RIB with statistics."; uses rib-statistics; } augment "/rt:routing/rt:ribs/rt:rib/" + "rt:routes/rt:route" { description "Augment a route in the RIB with common attributes."; leaf metric { when "not(derived-from(" + "../rt:source-protocol, 'ospf:ospf')) " + "and not(derived-from( " + "../rt:source-protocol, 'isis:isis'))" { description "This augmentation is only valid for routes that don't have OSPF or IS-IS as the source protocol. The YANG data models for OSPF and IS-IS already include a 'metric' augmentation for routes."; } type uint32; description "The metric is a numeric value indicating the cost of the route from the perspective of the routing protocol installing the route. In general, routes with a lower metric installed by the same routing protocol are lower cost to reach and are preferable to routes with a higher metric. However, metrics from different routing protocols are not comparable."; } leaf-list tag { when "not(derived-from(" + "../rt:source-protocol, 'ospf:ospf')) " + "and not(derived-from( " + "../rt:source-protocol, 'isis:isis'))" { description "This augmentation is only valid for routes that don't have OSPF or IS-IS as the source protocol. The YANG data models for OSPF and IS-IS already include a 'tag' augmentation for routes."; } type uint32; description "A tag is a 32-bit opaque value associated with the route that can be used for policy decisions such as advertisement and filtering of the route."; } leaf application-tag { type uint32; description "The application-specific tag is an additional tag that can be used by applications that require semantics and/or policy different from that of the tag. For example, the tag is usually automatically advertised in OSPF AS-External Link State Advertisements (LSAs) while this application-specific tag is not advertised implicitly."; } } augment "/rt:routing/rt:ribs/rt:rib/" + "rt:routes/rt:route/rt:next-hop/rt:next-hop-options/" + "rt:simple-next-hop" { description "Augment 'simple-next-hop' with 'repair-path'."; uses repair-path; } augment "/rt:routing/rt:ribs/rt:rib/" + "rt:routes/rt:route/rt:next-hop/rt:next-hop-options/" + "rt:next-hop-list/rt:next-hop-list/rt:next-hop" { description "Augment the next hop with a repair path."; uses repair-path; } } ]]>

Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF or RESTCONF . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) . The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS . The Network Configuration Access Control Model (NACM) 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. There are a number of data nodes defined in the ietf-rib-extension.yang module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:

• /v4ur:next-hop-options/v4ur:simple-next-hop/rib-ext:preference
• /v4ur:next-hop-options/v4ur:simple-next-hop/rib-ext:tag
• /v4ur:next-hop-options/v4ur:next-hop-list/v4ur:next-hop-list /v4ur:next-hop/rib-ext:preference
• /v4ur:next-hop-options/v4ur:next-hop-list/v4ur:next-hop-list /v4ur:next-hop/rib-ext:tag
• /v6ur:next-hop-options/v6ur:simple-next-hop/rib-ext:preference
• /v6ur:next-hop-options/v6ur:simple-next-hop/rib-ext:tag
• /v6ur:next-hop-options/v6ur:next-hop-list/v6ur:next-hop-list /v6ur:next-hop/rib-ext:preference
• /v6ur:next-hop-options/v6ur:next-hop-list/v6ur:next-hop-list /v6ur:next-hop/rib-ext:tag

For these augmentations to ietf-routing.yang, the ability to delete, add, and modify IPv4 and IPv6 static route preferences and tags would allow traffic to be misrouted. Some of the readable data nodes in the ietf-rib-extension.yang module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

• /rt:routing/rt:ribs/rt:rib/rib-ext:statistics
• /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rib-ext:metric
• /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rib-ext:tag
• /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rib-ext:application-tag
• /rt:route/rt:next-hop/rt:next-hop-options/rt:simple-next-hop/rib-ext:repair-path
• /rt:routes/rt:route/rt:next-hop/rt:next-hop-options/rt:next-hop-list/rt:next-hop-list/rt:next-hop/rib-ext:repair-path

Exposing the RIB will expose the routing topology of the network. This may be undesirable due to the fact that such exposure may facilitate other attacks. Additionally, network operators may consider their topologies to be sensitive confidential data. All the security considerations for writable and readable data nodes defined in apply to the augmentations described herein.

IANA Considerations This document registers the following URI in the "IETF XML Registry" .

URI:

urn:ietf:params:xml:ns:yang:ietf-rib-extension

Registrant Contact:

The IESG.

XML:

N/A; the requested URI is an XML namespace.

IANA has registered the following YANG module in the "YANG Module Names" registry .

Name:

ietf-rib-extension

Namespace:

urn:ietf:params:xml:ns:yang:ietf-rib-extension

Prefix:

rib-ext

Reference:

RFC 9403

References Normative References World Wide Web Consortium Recommendation REC-xml-20081126 Informative References

Combined Tree Diagram This appendix provides the combined ietf-routing.yang, ietf-ipv4-unicast-routing.yang, ietf-ipv6-unicast-routing.yang, and ietf-rib-extension.yang tree diagram.

ietf-rib-extension.yang example The following is an XML example using the RIB extension module and RFC 8349. static static-routing-protocol 0.0.0.0/0 192.0.2.2 30 99 ::/0 2001:db8:aaaa::1111 30 66 ipv4-primary v4ur:ipv4-unicast true 0.0.0.0/0 192.0.2.2 5 static 2015-10-24T18:02:45+02:00 198.51.100.0/24\ 192.0.2.2 203.0.113.1 200 120 rip:rip 2015-10-24T18:02:45+02:00 ipv6-primary v6ur:ipv6-unicast true 0::/0 2001:db8:aaaa::1111\ 5 static 2015-10-24T18:02:45+02:00 2001:db8:bbbb::/64\ 2001:db8:aaaa::1111\ 2001:db8:cccc::2222 200 120 rip:rip 2015-10-24T18:02:45+02:00 ]]> The following is the same example using JSON format .

Acknowledgments The authors wish to thank , , and for their helpful comments and suggestions. The authors wish to thank , , , , , , , and for their reviews and comments.