Network Working Group A. Mishra Internet-Draft Aalyria Technologies Intended status: Standards Track M. Jethanandani Expires: 3 August 2024 Kloud Services A. Saxena Ciena Corporation S. Pallagatti VMware M. Chen Huawei P. Fan China Mobile 31 January 2024 BFD Stability draft-ietf-bfd-stability-12 Abstract This document describes extensions to the Bidirectional Forwarding Detection (BFD) protocol to measure BFD stability. Specifically, it describes a mechanism for detection of BFD packet loss. 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 3 August 2024. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Mishra, et al. Expires 3 August 2024 [Page 1] Internet-Draft BFD Stability January 2024 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Functionality . . . . . . . . . . . . . . . . . . . . . . . . 3 5. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 3 5.1. Loss Measurement . . . . . . . . . . . . . . . . . . . . 4 6. Stability YANG Module . . . . . . . . . . . . . . . . . . . . 4 6.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 4 6.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7.1. The "IETF XML" Registry . . . . . . . . . . . . . . . . . 11 7.2. The "YANG Module Names" Registry . . . . . . . . . . . . 11 8. Security Consideration . . . . . . . . . . . . . . . . . . . 11 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 11. Normative References . . . . . . . . . . . . . . . . . . . . 12 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14 A.1. Single Hop BFD Configuration . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction The Bidirectional Forwarding Detection (BFD) [RFC5880] protocol operates by transmitting and receiving BFD control packets, generally at high frequency, over the datapath being monitored. In order to prevent significant data loss due to a datapath failure, BFD session detection time as defined in BFD [RFC5880] is set to the smallest feasible value. This document proposes a mechanism to detect lost packets in a BFD session in addition to the datapath fault detection mechanisms of BFD. Such a mechanism presents significant value to measure the stability of BFD sessions and provides data to the operators for the cause of a BFD failure. Mishra, et al. Expires 3 August 2024 [Page 2] Internet-Draft BFD Stability January 2024 This document does not propose any BFD extension to measure data traffic loss or delay on a link or tunnel and the scope is limited to BFD packets. 2. Terminology 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 RFC 2119 [RFC2119] and RFC 8174 [RFC8174]. The reader is expected to be familiar with the BFD [RFC5880], Optimizing BFD Authentication [I-D.ietf-bfd-optimizing-authentication] and BFD Secure Sequence Numbers [I-D.ietf-bfd-secure-sequence-numbers]. 3. Use Cases Bidirectional Forwarding Detection as defined in BFD [RFC5880] cannot detect any BFD packet loss if the loss does not last for detection time. This document proposes a method to detect a dropped packet on the receiver. For example, if the receiver receives BFD control packet k at time t but receives packet k+3 at time t+10ms, and never receives packet k+1 and/or k+2, then it has experienced a drop. This proposal enables BFD implementations to generate diagnostic information on the health of each BFD session that could be used to preempt a failure on a datapath that BFD was monitoring by allowing time for a corrective action to be taken. In a faulty datapath scenario, an operator can use BFD health information to trigger delay and loss measurement OAM protocol (Connectivity Fault Management (CFM) or Loss Measurement (LM)-Delay Measurement (DM)) to further isolate the issue. 4. Functionality The functionality proposed for BFD stability measurement is achieved by configuring the 'stability' flag in the attached YANG model in conjunction with BFD Meticulous Authentication. 5. Theory of Operation This mechanism allows operators to measure the loss of BFD control packets. Mishra, et al. Expires 3 August 2024 [Page 3] Internet-Draft BFD Stability January 2024 When using MD5 or SHA authentication, BFD MUST use an authentication type (bfd.AuthType) that is of type meticulous. Similarly, if BFD uses the OPT bfd.AuthType as defined in Optimizing BFD Authentication [I-D.ietf-bfd-optimizing-authentication], the authentication method it chooses MUST be of type meticulous. 5.1. Loss Measurement Loss measurement counts the number of BFD control packets missed at the receiver during any Detection Time period. The loss is detected by comparing the Sequence Number field in successive BFD control packets. The Sequence Number in each successive control packet generated on a BFD session by the transmitter is incremented by one. This loss count can then be exposed using the YANG module defined in the subsequent section. The first BFD authentication section with a non-zero sequence number, in a valid BFD control packet, processed by the receiver is used for bootstrapping the logic. 6. Stability YANG Module 6.1. Data Model Overview This YANG module augments the "ietf-bfd" module to add a flag 'stability' to enable this feature. The feature statement 'stability' needs to be enabled to indicate that BFD Stability is supported by the implementation. In addition, a loss count per- session or lsp for BFD packets that are lost has also been added in this model. Mishra, et al. Expires 3 August 2024 [Page 4] Internet-Draft BFD Stability January 2024 module: ietf-bfd-stability augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh /bfd-ip-sh:sessions/bfd-ip-sh:session: +--rw stability? boolean {stability}? augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh /bfd-ip-mh:session-groups/bfd-ip-mh:session-group: +--rw stability? boolean {stability}? augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-lag:lag /bfd-lag:sessions/bfd-lag:session: +--rw stability? boolean {stability}? augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls /bfd-mpls:session-groups/bfd-mpls:session-group: +--rw stability? boolean {stability}? augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh /bfd-ip-sh:sessions/bfd-ip-sh:session /bfd-ip-sh:session-statistics: +--ro lost-packet-count? yang:counter32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh /bfd-ip-mh:session-groups/bfd-ip-mh:session-group /bfd-ip-mh:sessions/bfd-ip-mh:session-statistics: +--ro lost-packet-count? yang:counter32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-lag:lag /bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links /bfd-lag:micro-bfd-ipv4/bfd-lag:session-statistics: +--ro lost-packet-count? yang:counter32 augment /rt:routing/rt:control-plane-protocols /rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls /bfd-mpls:session-groups/bfd-mpls:session-group /bfd-mpls:sessions/bfd-mpls:session-statistics: +--ro lost-packet-count? yang:counter32 6.2. YANG Module This YANG module imports Common YANG Types [RFC6991], A YANG Data Model for Routing [RFC8349], and YANG Data Model for Bidirectional Forwading Detection (BFD) [RFC9314]. Mishra, et al. Expires 3 August 2024 [Page 5] Internet-Draft BFD Stability January 2024 file "ietf-bfd-stability@2024-01-31.yang" module ietf-bfd-stability { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-stability"; prefix "bfds"; import ietf-yang-types { prefix "yang"; reference "RFC 6991: Common YANG Data Types"; } import ietf-routing { prefix "rt"; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA version)"; } import ietf-bfd { prefix bfd; reference "RFC 9314: YANG Data Model for Bidirectional Forwarding Detection."; } import ietf-bfd-ip-sh { prefix bfd-ip-sh; reference "RFC 9314: YANG Data Model for Bidirectional Forwarding Detection."; } import ietf-bfd-ip-mh { prefix bfd-ip-mh; reference "RFC 9314: YANG Data Model for Bidirectional Forwarding Detection."; } import ietf-bfd-lag { prefix bfd-lag; reference "RFC 9314: YANG Data Model for Bidirectional Forwarding Detection."; } import ietf-bfd-mpls { Mishra, et al. Expires 3 August 2024 [Page 6] Internet-Draft BFD Stability January 2024 prefix bfd-mpls; reference "RFC 9314: YANG Data Model for Bidirectional Forwarding Detection."; } organization "IETF BFD Working Group"; contact "WG Web: WG List: Authors: Mahesh Jethanandani (mjethanandani@gmail.com) Ashesh Mishra (mishra.ashesh@gmail.com) Ankur Saxena (ankurpsaxena@gmail.com) Santosh Pallagatti (santosh.pallagati@gmail.com) Mach Chen (mach.chen@huawei.com) Peng Fan (fanp08@gmail.com)."; description "This YANG module augments the base BFD YANG model to add attributes related to BFD Stability. In particular it adds a a per session count for BFD packets that are lost. Copyright (c) 2024 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 (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision "2024-01-31" { description Mishra, et al. Expires 3 August 2024 [Page 7] Internet-Draft BFD Stability January 2024 "Initial Version."; reference "RFC XXXX, BFD Stability."; } feature stability { description "If supported, the feature allows for BFD sessions to be monitored for frames lost."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "bfd-ip-sh:sessions/bfd-ip-sh:session" { leaf stability { if-feature "stability"; type boolean; must "../bfd-ip-sh:authentication/bfd-ip-sh:meticulous = " + "'true'"; default false; description "If set to true, this enables the BFD session to monitor for stability; i.e., to watch how many frames are getting dropped."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" + "bfd-ip-mh:session-groups/bfd-ip-mh:session-group" { leaf stability { if-feature "stability"; type boolean; must "../bfd-ip-mh:authentication/bfd-ip-mh:meticulous = " + "'true'"; default false; description "If set to true, this enables the BFD session to monitor for stability; i.e., to watch how many frames are getting dropped."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } Mishra, et al. Expires 3 August 2024 [Page 8] Internet-Draft BFD Stability January 2024 augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" + "bfd-lag:sessions/bfd-lag:session" { leaf stability { if-feature "stability"; type boolean; must "../bfd-lag:authentication/bfd-lag:meticulous = " + "'true'"; default false; description "If set to true, this enables the BFD session to monitor for stability; i.e., to watch how many frames are getting dropped."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" + "bfd-mpls:session-groups/bfd-mpls:session-group" { leaf stability { if-feature "stability"; type boolean; must "../bfd-mpls:authentication/bfd-mpls:meticulous = " + "'true'"; default false; description "If set to true, this enables the BFD session to monitor for stability; i.e., to watch how many frames are getting dropped."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh/" + "bfd-ip-sh:sessions/bfd-ip-sh:session/" + "bfd-ip-sh:session-statistics" { leaf lost-packet-count { type yang:counter32; description "Number of BFD packets that were lost without bringing the session down. This counter should be present only if stability is configured."; Mishra, et al. Expires 3 August 2024 [Page 9] Internet-Draft BFD Stability January 2024 } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" + "bfd-ip-mh:session-groups/bfd-ip-mh:session-group/" + "bfd-ip-mh:sessions/bfd-ip-mh:session-statistics" { leaf lost-packet-count { type yang:counter32; description "Number of BFD packets that were lost without bringing the session down. This counter should be present only if stability is configured."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" + "bfd-lag:sessions/bfd-lag:session/bfd-lag:member-links/" + "bfd-lag:micro-bfd-ipv4/bfd-lag:session-statistics" { leaf lost-packet-count { type yang:counter32; description "Number of BFD packets that were lost without bringing the session down. This counter should be present only if stability is configured."; } description "Augment the 'bfd' container to add attributes related to BFD stability."; } augment "/rt:routing/rt:control-plane-protocols/" + "rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" + "bfd-mpls:session-groups/bfd-mpls:session-group/" + "bfd-mpls:sessions/bfd-mpls:session-statistics" { leaf lost-packet-count { type yang:counter32; description "Number of BFD packets that were lost without bringing the session down. This counter should be present only if stability is configured."; Mishra, et al. Expires 3 August 2024 [Page 10] Internet-Draft BFD Stability January 2024 } description "Augment the 'bfd' container to add attributes related to BFD stability."; } } 7. IANA Considerations 7.1. The "IETF XML" Registry This document registers one URIs in the "ns" subregistry of the "IETF XML" registry [RFC3688]. Following the format in [RFC3688], the following registration is requested: URI: urn:ietf:params:xml:ns:yang:ietf-bfd-stability Registrant Contact: The IESG XML: N/A, the requested URI is an XML namespace. 7.2. The "YANG Module Names" Registry This document registers one YANG modules in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registrations are requested: name: ietf-bfd-stability namespace: urn:ietf:params:xml:ns:yang:ietf-bfd-stability prefix: bfds reference: RFC XXXX 8. Security Consideration 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 (NACM) [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 does not define any writeable/creatable/deletable data nodes that can have an adverse impact on a BFD session. Mishra, et al. Expires 3 August 2024 [Page 11] Internet-Draft BFD Stability January 2024 The only readable data nodes in 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. The model defines a read-only variables to indicate the number of packets that were lost. Access to this information may allow a malicious user information on which links are experiencing issues. The YANG module does not define any RPC operations. 9. Contributors The authors of this document would like to acknowledge Jeff Haas as a contributor to this document. Jeff played a role not only as a shepherd but also actively contributed to the improvement of the document. In addition, Manav Bhatia also contributed to this document. 10. Acknowledgements Authors would like to thank Nobo Akiya, Jeffery Haas, Dileep Singh, Basil Saji, Sagar Soni, Albert Fu and Mallik Mudigonda who also contributed to this document. 11. Normative References [I-D.ietf-bfd-optimizing-authentication] Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia, "Optimizing BFD Authentication", Work in Progress, Internet-Draft, draft-ietf-bfd-optimizing-authentication- 13, 1 August 2021, . [I-D.ietf-bfd-secure-sequence-numbers] DeKok, A., Jethanandani, M., Agarwal, S., Mishra, A., and A. Saxena, "Secure BFD Sequence Numbers", Work in Progress, Internet-Draft, draft-ietf-bfd-secure-sequence- numbers-12, 29 November 2023, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Mishra, et al. Expires 3 August 2024 [Page 12] Internet-Draft BFD Stability January 2024 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [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, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, 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, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Mishra, et al. Expires 3 August 2024 [Page 13] Internet-Draft BFD Stability January 2024 [RFC9314] Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed., Pallagatti, S., and G. Mirsky, "YANG Data Model for Bidirectional Forwarding Detection (BFD)", RFC 9314, DOI 10.17487/RFC9314, September 2022, . Appendix A. Examples This section tries to show some examples in how the model can be configured for stability. A.1. Single Hop BFD Configuration This example demonstrates how a Single Hop BFD session can be configured to enable monitoring of a session for stability. =============== NOTE: '\' line wrapping per RFC 8792 =============== bfd-stability-config "An example for BFD Stabalized configuration." 55 2017-01-01T00:00:00Z 2017-02-01T00:00:00Z 2016-12-31T23:59:55Z 2017-02-01T00:00:05Z kc:sha-1 eth0 if-type:ethernetCsmacd Mishra, et al. Expires 3 August 2024 [Page 14] Internet-Draft BFD Stability January 2024 bfd-types:bfdv1 name:BFD eth0 2001:db8:0:113::101 10000 10000 true bfd-stability-config true Authors' Addresses Ashesh Mishra Aalyria Technologies Email: ashesh@aalyria.com Mahesh Jethanandani Kloud Services CA United States of America Email: mjethanandani@gmail.com Mishra, et al. Expires 3 August 2024 [Page 15] Internet-Draft BFD Stability January 2024 Ankur Saxena Ciena Corporation 3939 North 1st Street San Jose, CA 95134 United States of America Email: ankurpsaxena@gmail.com URI: www.ciena.com Santosh Pallagatti VMware Bangalore 560103 Karnataka India Email: santosh.pallagatti@gmail.com Mach Chen Huawei Email: mach.chen@huawei.com Peng Fan China Mobile 32 Xuanwumen West Street Beijing Beijing, China Email: fanp08@gmail.com Mishra, et al. Expires 3 August 2024 [Page 16]