Network Working Group A. Mishra Internet-Draft SES Intended status: Standards Track M. Jethanandani Expires: January 14, 2021 Kloud Services A. Saxena Ciena Corporation S. Pallagatti VmWare M. Chen Huawei P. Fan China Mobile July 13, 2020 BFD Stability draft-ietf-bfd-stability-06 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 January 14, 2021. Copyright Notice Copyright (c) 2020 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 Mishra, et al. Expires January 14, 2021 [Page 1] Internet-Draft BFD Stability July 2020 (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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. BFD Null-Authentication Type . . . . . . . . . . . . . . . . 3 5. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 3 5.1. Loss Measurement . . . . . . . . . . . . . . . . . . . . 3 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. Security Consideration . . . . . . . . . . . . . . . . . . . 4 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 10. Normative References . . . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 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 packet 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. 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", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119] and RFC 8174 [RFC8174]. Mishra, et al. Expires January 14, 2021 [Page 2] Internet-Draft BFD Stability July 2020 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 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 implementation to generate diagnostic information on the health of each BFD session that could be used to preempt a failure on a link 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. BFD Null-Authentication Type The functionality proposed for BFD stability measurement is achieved by appending the Null-Authentication type (as defined in Optimizing BFD Authentication [I-D.ietf-bfd-optimizing-authentication] ) to the BFD control packets that do not have authentication enabled. 5. Theory of Operation This mechanism allows operators to measure the loss of BFD control packets. When using MD5 or SHA authentication, BFD uses authentication TLV that carries the Sequence Number. However, if non-meticulous authentication is being used, or no authentication is in use, then the non-authenticated BFD packets MUST include NULL-Auth TLV. 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 the Auth TLV (NULL or otherwise) in successive BFD control packets. The Sequence Number in Mishra, et al. Expires January 14, 2021 [Page 3] Internet-Draft BFD Stability July 2020 each successive control packet generated on a BFD session by the transmitter is incremented by one. The first BFD NULL-Auth type processed by the receiver that has a non-zero sequence number is used for bootstrapping the logic. When using secure sequence numbers, if the expected values are pre- calculated, the value must be matched to detect lost packets as defined in BFD secure sequence numbers [I-D.ietf-bfd-secure-sequence-numbers]. 6. IANA Considerations This document has no actions for IANA. 7. Security Consideration Other than concerns raised in BFD [RFC5880], Optimizing BFD Authentication [I-D.ietf-bfd-optimizing-authentication] and BFD Secure Sequence Numbers [I-D.ietf-bfd-secure-sequence-numbers]. There are no new concerns with this proposal. 8. Contributors Manav Bhatia 9. Acknowledgements Authors would like to thank Nobo Akiya, Jeffery Haas, Peng Fan, Dileep Singh, Basil Saji, Sagar Soni and Mallik Mudigonda who also contributed to this document. 10. Normative References [I-D.ietf-bfd-optimizing-authentication] Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia, "Optimizing BFD Authentication", draft-ietf-bfd- optimizing-authentication-09 (work in progress), December 2019. [I-D.ietf-bfd-secure-sequence-numbers] Jethanandani, M., Agarwal, S., Mishra, A., Saxena, A., and A. DeKok, "Secure BFD Sequence Numbers", draft-ietf-bfd- secure-sequence-numbers-05 (work in progress), February 2020. Mishra, et al. Expires January 14, 2021 [Page 4] Internet-Draft BFD Stability July 2020 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Authors' Addresses Ashesh Mishra SES Email: mishra.ashesh@gmail.com Mahesh Jethanandani Kloud Services CA USA Email: mjethanandani@gmail.com Ankur Saxena Ciena Corporation 3939 North 1st Street San Jose, CA 95134 USA Email: ankurpsaxena@gmail.com URI: www.ciena.com Santosh Pallagatti VmWare Bangalore, Karnataka 560103 India Email: santosh.pallagatti@gmail.com Mishra, et al. Expires January 14, 2021 [Page 5] Internet-Draft BFD Stability July 2020 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 January 14, 2021 [Page 6]