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rtg lsr This document defines a YANG module for managing the reverse metric extension to the Intermediate System to Intermediate System (IS-IS) intra-domain routing information exchange protocol.

Introduction This document defines a YANG module for managing the reverse metric extension to IS-IS . Please refer to for the description and definition of the functionality managed by this module. The YANG data model described in this document conforms to the Network Management Datastore Architecture defined in .

YANG Management

YANG Tree The following is the YANG tree diagram for the IS-IS reverse metric extension additions.

YANG Module The following is the YANG module for managing the IS-IS reverse metric functionality defined in . It imports modules from and . This YANG module uses the same per-level hierarchical configuration structure as that defined in the augmented base module. WG List: Author: Christian Hopps "; description "This module defines the configuration and operational state for managing the IS-IS reverse metric functionality (RFC 8500). Copyright (c) 2022 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 9194; see the RFC itself for full legal notices."; reference "RFC 8500: IS-IS Routing with Reverse Metric"; revision 2022-10-19 { description "Initial revision."; reference "RFC 9194: A YANG Module for IS-IS Reverse Metric"; } grouping reverse-metric-data { description "IS-IS reverse metric data."; leaf metric { type isis:wide-metric; description "The reverse metric value."; reference "RFC 8500: IS-IS Routing with Reverse Metric, Section 2"; } container flags { description "The reverse metric flag values."; leaf whole-lan { type boolean; description "The 'Whole LAN' bit (W bit) (RFC 8500). If true, then a Designated Intermediate System (DIS) processing this reverse metric will add the metric value to all the nodes it advertises in the pseudonode Link State Protocol Data Unit (LSP) for this interface. Otherwise, it will only increment the metric for the advertising node in the pseudonode LSP for this interface."; reference "RFC 8500: IS-IS Routing with Reverse Metric, Section 2"; } leaf allow-unreachable { type boolean; description "The 'Unreachable' bit (U bit) (RFC 8500). If true, it allows the neighbor to increment the overall metric up to 2^24-1 rather than the lesser maximum of 2^24-2. If the metric is then set by the neighbor to 2^24-1, it will cause traffic to stop using, rather than avoid using, the interface."; reference "RFC 8500: IS-IS Routing with Reverse Metric, Section 2"; } } } grouping reverse-metric-if-config-data { description "IS-IS reverse metric config data."; uses reverse-metric-data; leaf exclude-te-metric { type boolean; default "false"; description "If true and there is a TE metric defined for this interface, then do not send the Traffic Engineering Metric sub-TLV in the Reverse Metric TLV."; reference "RFC 8500: IS-IS Routing with Reverse Metric, Section 2"; } } grouping tlv16-reverse-metric { description "IS-IS Reverse Metric TLV data."; uses reverse-metric-data; leaf te-metric { type uint32; description "The TE metric value from the sub-TLV, if present."; reference "RFC 8500: IS-IS Routing with Reverse Metric, Section 2"; } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "isis:isis" { when "derived-from-or-self(../rt:type, 'isis:isis')" { description "This augment is only valid when the routing protocol instance type is 'isis'."; } description "The reverse metric configuration for an IS-IS instance."; container reverse-metric { description "Global reverse metric configuration."; leaf enable-receive { type boolean; default "false"; description "Enables handling of reverse metric announcements from neighbors. By default, reverse metric handling is disabled and must be explicitly enabled through this configuration."; } } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "isis:isis/isis:interfaces/isis:interface" { when "derived-from-or-self(../../../rt:type, 'isis:isis')" { description "This augment is only valid when the routing protocol instance type is 'isis'."; } description "The reverse metric configuration for an interface."; container reverse-metric { description "Announces a reverse metric to neighbors. The configuration is hierarchical and follows the same behavior as that defined for per-level values in the augmented base module. Reverse metric operation is enabled by the configuration of a 'reverse-metric' metric value either at the top level or under a level-specific container node. If a 'reverse-metric' metric value is only specified under a level-specific container node, then operation is only enabled at the specified level. As the reverse metric is advertised in IS-IS Hello Protocol Data Units (IIH PDUs), level-specific configuration is only available for broadcast interface types."; uses reverse-metric-if-config-data { refine "flags/whole-lan" { default "false"; } refine "flags/allow-unreachable" { default "false"; } } container level-1 { when '../../isis:interface-type = "broadcast"'; description "Announces a reverse metric to level-1 neighbors."; uses reverse-metric-if-config-data; } container level-2 { when '../../isis:interface-type = "broadcast"'; description "Announces a reverse metric to level-2 neighbors."; uses reverse-metric-if-config-data; } } } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/" + "isis:isis/isis:interfaces/isis:interface/" + "isis:adjacencies/isis:adjacency" { when "derived-from-or-self(../../../../../rt:type, 'isis:isis')" { description "This augment is only valid when the routing protocol instance type is 'isis'."; } description "The reverse metric state advertised by an adjacency."; container reverse-metric { description "IS-IS Reverse Metric TLV data."; uses tlv16-reverse-metric; } } } ]]>

IANA Considerations

Updates to the IETF XML Registry This document registers a URI in the "IETF XML Registry" . Following the format in , the following registration has been made:

URI:

urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric

Registrant Contact:

The IESG.

XML:

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

Updates to the YANG Module Names Registry This document registers one YANG module in the "YANG Module Names" registry . Following the format in , the following registration has been made:

Name:

ietf-isis-reverse-metric

Maintained by IANA?

N

Namespace:

urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric

Prefix:

isis-rmetric

Reference:

RFC 9194

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. The YANG module defined in this document can enable, disable, and modify the behavior of metrics used by routing. For the security implications regarding these types of changes, consult -- which defines the functionality -- as well as . There are a number of data nodes defined in this 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 YANG nodes correspond directly to the functionality provided in RFC 8500, and the security considerations of the functionality are described in RFC 8500. These are the subtrees and data nodes: Some of the readable data nodes in this 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 YANG nodes correspond directly to the functionality provided in RFC 8500, and the security considerations of the functionality are described in RFC 8500. These are the subtrees and data nodes:

Normative References ISO International Standard 10589: 2002, Second Edition World Wide Web Consortium Recommendation REC-xml-20081126 Informative References

Examples

Enablement Example Using XML YANG Instance Data Below is an example of XML YANG instance data to enable reverse metric processing.

Example XML Data to Enable Reverse Metric Processing isis:isis default 00 true ]]>

Usage Example Using XML YANG Instance Data Below is an example of XML YANG instance data for the "ietf-isis-reverse-metric" module.

Example XML Data for the "ietf-isis-reverse-metric" Module eth0 ianaift:ethernetCsmacd isis:isis default 00 eth0 65535 ]]>

Usage Example Using JSON YANG Instance Data Below is an example of JSON YANG instance data for the "ietf-isis-reverse-metric" module.

Example JSON Data for the Level-1-Only Reverse Metric