Network Working Group C. Hopps Internet-Draft LabN Consulting, L.L.C. Intended status: Standards Track 1 January 2022 Expires: 5 July 2022 YANG Module for IS-IS Reverse Metric draft-ietf-lsr-yang-isis-reverse-metric-06 Abstract This document defines a YANG module for managing the reverse metric extension to the Intermediate System to Intermediate System intra- domain routeing information exchange protocol (IS-IS). Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 5 July 2022. Copyright Notice Copyright (c) 2022 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Hopps Expires 5 July 2022 [Page 1] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. YANG Management . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 3 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 3.1. Updates to the IETF XML Registry . . . . . . . . . . . . 8 3.2. Updates to the YANG Module Names Registry . . . . . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. Normative References . . . . . . . . . . . . . . . . . . . . 10 6. Informative References . . . . . . . . . . . . . . . . . . . 11 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 12 A.1. Enablement Example using XML YANG Instance Data . . . . . 12 A.2. Usage Example using XML YANG Instance Data . . . . . . . 13 A.3. Usage Example using JSON YANG Instance Data . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction This document defines a YANG module for managing the reverse metric extension to IS-IS [RFC8500], [ISO10589]. Please refer to [RFC8500] 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 [RFC8342]. 2. YANG Management 2.1. YANG Tree The following is the YANG tree diagram ([RFC8340]) for the IS-IS reverse metric extension additions. Hopps Expires 5 July 2022 [Page 2] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 module: ietf-isis-reverse-metric augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis: +--rw reverse-metric +--rw enable-receive? boolean augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:interfaces /isis:interface: +--rw reverse-metric +--rw metric? isis:wide-metric +--rw flags | +--rw whole-lan? boolean | +--rw allow-unreachable? boolean +--rw exclude-te-metric? boolean +--rw level-1 | +--rw metric? isis:wide-metric | +--rw flags | | +--rw whole-lan? boolean | | +--rw allow-unreachable? boolean | +--rw exclude-te-metric? boolean +--rw level-2 +--rw metric? isis:wide-metric +--rw flags | +--rw whole-lan? boolean | +--rw allow-unreachable? boolean +--rw exclude-te-metric? boolean augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/isis:isis/isis:interfaces /isis:interface/isis:adjacencies/isis:adjacency: +--ro reverse-metric +--ro metric? isis:wide-metric +--ro flags | +--ro whole-lan? boolean | +--ro allow-unreachable? boolean +--ro te-metric? uint32 2.2. YANG Module The following is the YANG module for managing the IS-IS reverse metric functionality defined in [RFC8500]. It imports modules from the following RFCs: [RFC8349], [I-D.ietf-isis-yang-isis-cfg]. This YANG module uses the same "Per-Level" hierarchical configuration structure as is defined in the augmented base module. Hopps Expires 5 July 2022 [Page 3] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 file "ietf-isis-reverse-metric@2022-01-01.yang" module ietf-isis-reverse-metric { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric"; prefix isis-rmetric; import ietf-routing { prefix rt; reference "RFC8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-isis { prefix isis; reference "draft-ietf-isis-yang-isis-cfg-42: YANG Data Model for IS-IS Protocol"; } organization "IETF LSR Working Group (LSR)"; contact "WG Web: WG List: Author: Christian Hopps "; // RFC Ed.: replace XXXX with actual RFC number and // remove this note. description "This module defines the configuration and operational state for managing the IS-IS reverse metric functionality [RFC8500]. 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 Simplified 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 (https://www.rfc-editor.org/info/rfcXXXX>); see the RFC itself Hopps Expires 5 July 2022 [Page 4] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 for full legal notices."; revision 2022-01-01 { description "Initial Revision"; reference "RFC XXXX: YANG 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 "RFC8500, Section 2"; } container flags { description "The reverse metric flag values."; leaf whole-lan { type boolean; description "The 'whole LAN' or W-bit. If true then a DIS processing this reverse metric will add the metric value to all the nodes it advertises in the pseudo-node LSP for this interface. Otherwise, it will only increment the metric for the advertising node in the pseudo-node LSP for this interface."; reference "RFC8500, Section 2"; } leaf allow-unreachable { type boolean; description "The 'allow-unreachable' or U-bit. 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 "RFC8500, 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 Hopps Expires 5 July 2022 [Page 5] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 "If true and there is a TE metric defined for this interface then do not send the TE metric sub-TLV in the reverse metric TLV."; reference "RFC8500, 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 "RFC8500, 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 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 "Enable 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" { Hopps Expires 5 July 2022 [Page 6] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 when "derived-from-or-self(../../../rt:type, 'isis:isis')" { description "This augment is only valid when routing protocol instance type is 'isis'."; } description "The reverse metric configuration for an interface."; container reverse-metric { description "Announce a reverse metric to neighbors. The configuration is hierarchical and follows the same behavior as defined for 'Per-Level' values in the augmented base module. Reverse metric operation is enabled by the configuration of a reverse-metric metric value at either 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 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 "Announce a reverse metric to level-1 neighbors."; uses reverse-metric-if-config-data; } container level-2 { when '../../isis:interface-type = "broadcast"'; description "Announce a reverse metric to level-2 neighbors."; uses reverse-metric-if-config-data; } } } augment "/rt:routing/rt:control-plane-protocols/" Hopps Expires 5 July 2022 [Page 7] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 +"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 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; } } } 3. IANA Considerations 3.1. Updates to the IETF XML Registry This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in [RFC3688], 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. 3.2. Updates to the YANG Module Names Registry This document registers one YANG module in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registration has been made: name ietf-isis-reverse-metric namespace urn:ietf:params:xml:ns:yang:ietf-isis-reverse-metric prefix isis-rmetric reference RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove this note.) Hopps Expires 5 July 2022 [Page 8] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 4. 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 [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]. 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 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 [RFC8500] which defines the functionality as well as [I-D.ietf-isis-yang-isis-cfg]. 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 RFC 8500 functionality and the security considerations of the functionality are described in RFC 8500. These are the subtrees and data nodes: Under "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/isis:isis" - /isis-rmetric:reverse-metric/isis-rmetric:enable-receive Under "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/isis:isis/" + "isis:interfaces/isis:interface/" + "isis-rmetric:reverse-metric" - /isis-rmetric:metric - /isis-rmetric:flags/isis-rmetric:whole-lan - /isis-rmetric:flags/isis-rmetric:allow-unreachable - /isis-rmetric:exclude-te-metric Hopps Expires 5 July 2022 [Page 9] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 Under "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/isis:isis/" + "isis:interfaces/isis:interface/" + "isis-rmetric:reverse-metric/" + "isis-rmetric:level-1/" - /isis-rmetric:metric - /isis-rmetric:flags/isis-rmetric:whole-lan - /isis-rmetric:flags/isis-rmetric:allow-unreachable - /isis-rmetric:exclude-te-metric Under "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/isis:isis/" + "isis:interfaces/isis:interface/" + "isis-rmetric:reverse-metric/" + "isis-rmetric:level-2/" - /isis-rmetric:metric - /isis-rmetric:flags/isis-rmetric:whole-lan - /isis-rmetric:flags/isis-rmetric:allow-unreachable - /isis-rmetric:exclude-te-metric 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 RFC 8500 functionality and the security considerations of the functionality are described in RFC 8500. These are the subtrees and data nodes: Under "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/isis:isis/" + "isis:interfaces/isis:interface/" + "isis:adjacencies/isis:adjacency/" + "isis-rmetric:reverse-metric" - /isis-rmetric:metric - /isis-rmetric:flags/isis-rmetric:whole-lan - /isis-rmetric:flags/isis-rmetric:allow-unreachable - /isis-rmetric:te-metric 5. Normative References Hopps Expires 5 July 2022 [Page 10] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 [ISO10589] International Organization for Standardization, "Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473)", ISO Standard 10589:2002, 2002. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, March 2018, . [RFC8500] Shen, N., Amante, S., and M. Abrahamsson, "IS-IS Routing with Reverse Metric", RFC 8500, DOI 10.17487/RFC8500, February 2019, . [I-D.ietf-isis-yang-isis-cfg] Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L. Lhotka, "YANG Data Model for IS-IS Protocol", Work in Progress, Internet-Draft, draft-ietf-isis-yang-isis-cfg- 42, 15 October 2019, . 6. Informative References Hopps Expires 5 July 2022 [Page 11] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 [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, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Appendix A. Examples A.1. Enablement Example using XML YANG Instance Data Below is an example of XML YANG instance data [RFC8342] to enable reverse metric processing. Hopps Expires 5 July 2022 [Page 12] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 isis:isis default 00 true Figure 1: Example XML data to enable reverse metric processing. A.2. Usage Example using XML YANG Instance Data Below is an example of XML YANG instance data [RFC8342] for the ietf- isis-reverse-metric module. Hopps Expires 5 July 2022 [Page 13] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 eth0 ianaift:ethernetCsmacd isis:isis default 00 eth0 65535 Figure 2: Example XML data for ietf-isis-reverse-metric module. A.3. Usage Example using JSON YANG Instance Data Below is an example of JSON YANG instance data [RFC7951] for the ietf-isis-reverse-metric module. Hopps Expires 5 July 2022 [Page 14] Internet-Draft YANG Module for IS-IS Reverse Metric January 2022 { "ietf-interfaces:interfaces": { "interface": [ { "name": "eth0", "type": "iana-if-type:ethernetCsmacd" } ] }, "ietf-routing:routing": { "control-plane-protocols": { "control-plane-protocol": [ { "type": "ietf-isis:isis", "name": "default", "ietf-isis:isis": { "area-address": [ "00" ], "interfaces": { "interface": [ { "name": "eth0", "ietf-isis-reverse-metric:reverse-metric": { "level-1": { "metric": 65535, "exclude-te-metric": true } } } ] } } } ] } } } Figure 3: Example JSON data for level-1 only reverse metric. Author's Address Christian Hopps LabN Consulting, L.L.C. Email: chopps@chopps.org Hopps Expires 5 July 2022 [Page 15]