Internet DRAFT - draft-hwy-bfd-sdi
draft-hwy-bfd-sdi
BFD Working Group L. Han
Internet-Draft M. Wang
Intended status: Standards Track China Mobile
Expires: 27 June 2023 F. Yang
R. Tan
Huawei Technologies
24 December 2022
Signal Degrade Indication in BFD
draft-hwy-bfd-sdi-02
Abstract
To satisfy the requirements of signal degrade indication described in
[I-D.yang-mpls-ps-sdi-sr], this document illustrates the extension of
BFD protocol to support signal degrade indication.
Requirements Language
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].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 27 June 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Signal Degrade Overview . . . . . . . . . . . . . . . . . . . 3
3.1. Signal Degrade Definition . . . . . . . . . . . . . . . . 3
3.2. Signal Degrade vs Packet Loss Rate . . . . . . . . . . . 4
3.3. Use BFD to Support Signal Degrade Indication . . . . . . 4
3.4. Notification Spread in Network . . . . . . . . . . . . . 4
4. BFD Extension to Indicate Signal Degrade . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Background
Signal Degrade (SD) is categorized as one of triggers to bring
survivability challenge to networks [RFC4428]. Not like the signal
failure caused by failure of links or nodes, Signal Degrade (SD) is
normally caused by fiber aging, fiber impairment, fiber pollution,
optical module mismatch or WDM transmission error etc.
The detection and transmission of signal degrade is discussed in
[I-D.zhl-mpls-tp-sd] and [I-D.yang-mpls-ps-sdi-sr]. When signal
degrade is detected, it can be spread via control plane, forwarding
plane, or management plane, or combination of any of them.
BFD [RFC5880] and SBFD [RFC7880] are widely used as the failure
notification in networks due to the characteristics of simplicity and
efficiency. BFD also provides good opportunity to indicate signal
degrade by reflecting it in BFD state changes. This document extends
the BFD protocol to carry signal degrade indication in networks.
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2. Terminology
SD: Signal Degrade
BER: Bit Error Rate
MIP: Maintenance Entity Group Intermediate Point
PLR: Packet Loss Rate
FEC: Forwarding Error Correction
SLA: Service Level Agreement
BFD: Bidirectional Forwarding Detection
SBFD: Seamless BFD
OAM: Operation, Administration and Maintenance
3. Signal Degrade Overview
3.1. Signal Degrade Definition
In [IEEE 802.3-2018], Bit Error Rate (BER) is defined as the ratio of
the number of bits received in error to the total number of bits
received. It is one of parameters to indicate quality of physical
links. Depending on the Forwarding Error Correction (FEC) capability
of PHYs, BER can be classified into pre-FEC BER and post-FEC BER.
The pre-FEC BER value acquired from PHY on receiving port indicates
the on wire BER value of physical link. This value can also be
measured via external test instruments. Generally speaking, BER
specifically refers to pre-FEC BER. If FEC capability is unavailable
for some legacy PHYs, it is meaningless to differentiate pre-FEC and
post-FEC BER values.
Signal degrade can be detected based on the physical bit error
statistic on port level, no matter whether the PHY is with or without
Forwarding Error Correction. Port level statistic is an intuitive
approach to be best understood in the equipment and network systems.
In practice, flexible configuration of the watermark to trigger the
indication of signal degrade is also preferred.
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3.2. Signal Degrade vs Packet Loss Rate
In packet switched network, the measurement of physical link is based
on the unit of packet, resulting in either no packet loss or a number
of packet loss to indicate the status of link. Although PHYs are
defined in [IEEE 802.3-2018], vendors may have different
implementations to deal with the error bits when equipment detects
them. Moreover, bit is a fix unit, but packet has variable length.
Several error bits can lead to one packet loss, or multiple packets'
loss. There is no uniform approach to calculate pre-FEC BER into
PLR. It means there is no parameter directly indicated the status of
physical links in packet switched network.
3.3. Use BFD to Support Signal Degrade Indication
For the network where BFD is used to provide the fast failure
detection, the minimal detection interval e.g. 3.3ms actually leaves
a huge gap of data packets between two consecutive BFD packets when
the line rate packets are transmitted over high speed Ethernet link.
Take an example of 10Gbps link transmitting the packets with length
of 192 bytes to calculate, more than twenty thousand packets are
transmitted within 3.3ms. Note that the criteria to announce a
failure of BFD based on three consecutive BFD packet loss. It may
not be accurate to rely on BFD to detect and trigger the protection
mechanism if there is signal degrade on the physical link.
3.4. Notification Spread in Network
In current packet switched networks, the error bit information like
BER is only obtained and processed locally on each node. There is no
indication or advertisement of the errors or its indications of
physical links. It should be possible to spread this information via
control plane, management plane or even data plane to suit for
different needs. Especially, if the signal degrade of the link could
be transmitted in data plane and aware by any other nodes, local
repair or end-to-end path protection could be performed even more
efficiently. Previous work proposed in [I-D.rkhd-mpls-tp-sd],
[I-D.zhl-mpls-tp-sd] and [I-D.zhang-ccamp-rsvpte-ber-measure] give
the examples of protocol extensions to support SD transmission for
further network convergence behaviors. With the emerge of telemetry,
it is also possible to collect and report this information more
frequently to SDN controller to facilitate the network operation and
management.
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4. BFD Extension to Indicate Signal Degrade
The Diagnostic code in BFD specifies the local system's reason for
the last change in session state. The definition of the Values is
specified in Section 4.1 of [RFC5880].
In this document, reserved values from 9 to 31 are requested to IANA
to support the signal degrade indication and removal.
(preamble)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers | Diag |Sta|P|F|C|A|D|M| Detect Mult | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Your Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Desired Min TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min Echo RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BFD Packet Format
5. IANA Considerations
The document requires the definition of the new indication and
removal of the signal degrade indication in BFD Value code.
6. Security Considerations
TBD
7. References
7.1. Normative References
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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>.
[RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
Pallagatti, "Seamless Bidirectional Forwarding Detection
(S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
<https://www.rfc-editor.org/info/rfc7880>.
7.2. Informative References
[I-D.rkhd-mpls-tp-sd]
Ram, R., Cohn, D., Daikoku, M., Yuxia, M., and Y. Jian,
"SD detection and protection triggering in MPLS-TP", Work
in Progress, Internet-Draft, draft-rkhd-mpls-tp-sd-03, 31
May 2011, <https://www.ietf.org/archive/id/draft-rkhd-
mpls-tp-sd-03.txt>.
[I-D.yang-mpls-ps-sdi-sr]
Yang, F., Han, L., and J. Zhao, "Problem Statement of
Signal Degrade Indication for SR over MPLS", Work in
Progress, Internet-Draft, draft-yang-mpls-ps-sdi-sr-01, 2
November 2020, <https://www.ietf.org/archive/id/draft-
yang-mpls-ps-sdi-sr-01.txt>.
[I-D.zhang-ccamp-rsvpte-ber-measure]
Li, Z., Zhang, L., and G. Yang, "RSVP-TE Extensions for
Bit Error Rate (BER) Measurement", Work in Progress,
Internet-Draft, draft-zhang-ccamp-rsvpte-ber-measure-02, 3
July 2014, <https://www.ietf.org/archive/id/draft-zhang-
ccamp-rsvpte-ber-measure-02.txt>.
[I-D.zhl-mpls-tp-sd]
Haiyan, Z., Jia, H., and H. Li, "SD-Triggered Protection
Switching in MPLS-TP", Work in Progress, Internet-Draft,
draft-zhl-mpls-tp-sd-03, 25 October 2010,
<https://www.ietf.org/archive/id/draft-zhl-mpls-tp-sd-
03.txt>.
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[RFC4428] Papadimitriou, D., Ed. and E. Mannie, Ed., "Analysis of
Generalized Multi-Protocol Label Switching (GMPLS)-based
Recovery Mechanisms (including Protection and
Restoration)", RFC 4428, DOI 10.17487/RFC4428, March 2006,
<https://www.rfc-editor.org/info/rfc4428>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
Profile (MPLS-TP) Survivability Framework", RFC 6372,
DOI 10.17487/RFC6372, September 2011,
<https://www.rfc-editor.org/info/rfc6372>.
Authors' Addresses
Liuyan Han
China Mobile
No.32 Xuanwumen west street
Beijing, 100053
China
Email: hanliuyan@chinamobile.com
Minxue Wang
China Mobile
No.32 Xuanwumen west street
Beijing, 100053
China
Email: wangminxue@chinamobile.com
Fan Yang
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: shirley.yangfan@huawei.com
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Ren Tan
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: tanren@huawei.com
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