]> LabN Consulting LLC

301 Midenhall Way Cary NC USA 27513 acee.ietf@gmail.com

Futurewei

2330 Central Expressway Santa Clara CA 95050 USA yingzhen.qu@futurewei.com

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 which 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 RIB. The RIB selects the preferred or active route by comparing the route-preference (aka, administrative distance) of the candidate routes installed 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 in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342].

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
• RPC (Remote Procedure Call) operation

The following terms are defined in Section 5.2:

• 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

Design of the Model The YANG module defined in this document augments the ietf-routing YANG modules defined in , which provide a basis for routing system data model development. Together with YANG modules defined in , a generic RIB YANG model is defined 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 Preference 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 which augment static IPv4 unicast routes and IPv6 unicast routes next-hop.

Repair Path The IP Fast Reroute (IPFRR) calculation by routing protocol pre-computes 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 meaning of the symbols can be found in .

RIB Extension YANG Model 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 (NDMA) 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 XXXX; see the RFC itself for full legal notices."; revision 2023-06-06 { description "Initial Version"; reference "RFC XXXX: 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'."; } leaf active-routes { type uint32; description "Total number of active routes in the RIB for the routing protocol for the routing protocol identified by the 'protocol'. 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'."; } } } } grouping attributes { description "Common attributes applicable to all routes."; leaf metric { 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 { 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."; } } grouping repair-path { description "Grouping for IP Fast Reroute repair path."; container repair-path { description "IP Fast Reroute 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 IP Fast Reroute re-route repair is local and the metric is not advertised externally, the metric for 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 preference next-hop are preferred and equal preference routes result in Equal-Cost-Multi-Path (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 preference next-hop are preferred and equal preference routes result in Equal-Cost-Multi-Path (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 preference next-hop are preferred and equal preference routes result in Equal-Cost-Multi-Path (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 preference next-hop are preferred and equal preference routes result in Equal-Cost-Multi-Path (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 RIB with attributes."; uses attributes; } 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 NETCONF access control model provides the means to restrict access for particular NETCONF or RESTCONF users to a pre-configured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in ietf-rib-extensions.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 preference and tag would allow traffic to be misrouted.

Some of the readable data nodes in the ietf-rib-extensions.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
• The exposure of the Routing Information Base (RIB) will expose the routing topology of the network. This may be undesirable due to the fact that 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 apply to the augmentations described herein.

IANA Considerations This document registers a URI in the IETF XML registry . Following the format in , the following registration is requested to be made: This document registers a YANG module in the YANG Module Names registry .

References Normative References This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document describes a method for invoking and running the Network Configuration Protocol (NETCONF) within a Secure Shell (SSH) session as an SSH subsystem. This document obsoletes RFC 4742. [STANDARDS-TRACK] This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950. This document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics). The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342. This document obsoletes RFC 7223. This document specifies three YANG modules and one submodule. Together, they form the core routing data model that serves as a framework for configuring and managing a routing subsystem. It is expected that these modules will be augmented by additional YANG modules defining data models for control-plane protocols, route filters, and other functions. The core routing data model provides common building blocks for such extensions -- routes, Routing Information Bases (RIBs), and control-plane protocols. The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA). This document obsoletes RFC 8022. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. Informative References This document provides a framework for the development of IP fast- reroute mechanisms that provide protection against link or router failure by invoking locally determined repair paths. Unlike MPLS fast-reroute, the mechanisms are applicable to a network employing conventional IP routing and forwarding. This document is not an Internet Standards Track specification; it is published for informational purposes. This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. This document defines two strategies for handling long lines in width-bounded text content. One strategy, called the "single backslash" strategy, is based on the historical use of a single backslash ('\') character to indicate where line-folding has occurred, with the continuation occurring with the first character that is not a space character (' ') on the next line. The second strategy, called the "double backslash" strategy, extends the first strategy by adding a second backslash character to identify where the continuation begins and is thereby able to handle cases not supported by the first strategy. Both strategies use a self-describing header enabling automated reconstitution of the original content.

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

ietf-rib-extension.yang example The following is an XML example using the RIB extension module and RFC 8349. Note: '\' line wrapping per . 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\ 192.0.2.2 203.0.113.1 200 110 ospf:ospf 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 200 110 ospf:ospf 2015-10-24T18:02:45+02:00 ]]> The following is the same example using JSON format.

Acknowledgments The RFC text was produced using Marshall Rose's xml2rfc tool. The authors wish to thank Les Ginsberg, Krishna Deevi, and Suyoung Yoon for their helpful comments and suggestions. The authors wish to thank Tom Petch, Rob Wilton, Chris Hopps, Martin Bjorklund, Jeffrey Zhang, Eric Vyncke, Lars Eggert, and Bo Wu for their reviews and comments.