Network Working Group A. Mishra
Internet-Draft SES
Intended status: Standards Track M. Jethanandani
Expires: July 18, 2021 Kloud Services
A. Saxena
Ciena Corporation
S. Pallagatti
VmWare
M. Chen
Huawei
P. Fan
China Mobile
Jan 14, 2021
BFD Stability
draft-ietf-bfd-stability-07
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.
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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 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.
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].
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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. BFD Null-Authentication Type
The functionality proposed for BFD stability measurement is achieved
by appending an authentication section with 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 an authentication
section that carries the Sequence Number. However, if non-meticulous
authentication is being used, or no authentication is in use, then
the non-authenticated BFD control packets MUST include an
authentication section with the NULL Authentication type.
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
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otherwise) 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.
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. 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-11 (work in progress), July
2020.
[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-07 (work in progress), December
2020.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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
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Mach Chen
Huawei
Email: mach.chen@huawei.com
Peng Fan
China Mobile
32 Xuanwumen West Street
Beijing, Beijing
China
Email: fanp08@gmail.com
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