draft-ietf-bfd-unaffiliated-echo-03.txt   draft-ietf-bfd-unaffiliated-echo-04.txt 
BFD Working Group W. Cheng BFD Working Group W. Cheng
Internet-Draft R. Wang Internet-Draft R. Wang
Updates: 5880 (if approved) China Mobile Updates: 5880 (if approved) China Mobile
Intended status: Standards Track X. Min, Ed. Intended status: Standards Track X. Min, Ed.
Expires: 28 July 2022 ZTE Corp. Expires: 12 August 2022 ZTE Corp.
R. Rahman R. Rahman
Individual Individual
R. Boddireddy R. Boddireddy
Juniper Networks Juniper Networks
24 January 2022 8 February 2022
Unaffiliated BFD Echo Unaffiliated BFD Echo
draft-ietf-bfd-unaffiliated-echo-03 draft-ietf-bfd-unaffiliated-echo-04
Abstract Abstract
Bidirectional Forwarding Detection (BFD) is a fault detection Bidirectional Forwarding Detection (BFD) is a fault detection
protocol that can quickly determine a communication failure between protocol that can quickly determine a communication failure between
two forwarding engines. This document proposes a use of the BFD Echo two forwarding engines. This document proposes a use of the BFD Echo
where the local system supports BFD but the neighboring system does where the local system supports BFD but the neighboring system does
not support BFD. not support BFD.
This document updates RFC 5880. This document updates RFC 5880.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 July 2022. This Internet-Draft will expire on 12 August 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License. provided without warranty as described in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions Used in This Document . . . . . . . . . . . . 3 1.1. Conventions Used in This Document . . . . . . . . . . . . 3
2. Updates to RFC 5880 . . . . . . . . . . . . . . . . . . . . . 3 2. Updates to RFC 5880 . . . . . . . . . . . . . . . . . . . . . 3
3. Unaffiliated BFD Echo Procedures . . . . . . . . . . . . . . 6 3. Unaffiliated BFD Echo Procedures . . . . . . . . . . . . . . 6
4. Unaffiliated BFD Echo Applicability . . . . . . . . . . . . . 8 4. Unaffiliated BFD Echo Applicability . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 9.1. Normative References . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . 9 9.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
To minimize the impact of device/link faults on services and improve To minimize the impact of device/link faults on services and improve
network availability, a network device must be able to quickly detect network availability, a network device must be able to quickly detect
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The Unaffiliated BFD Echo described in this document reuses the BFD The Unaffiliated BFD Echo described in this document reuses the BFD
Echo function as described in [RFC5880] and [RFC5881], but does not Echo function as described in [RFC5880] and [RFC5881], but does not
require BFD Asynchronous or Demand mode. When using the Unaffiliated require BFD Asynchronous or Demand mode. When using the Unaffiliated
BFD Echo, only the local system has the BFD protocol enabled; the BFD Echo, only the local system has the BFD protocol enabled; the
remote system just loops back the received BFD Echo packets as remote system just loops back the received BFD Echo packets as
regular data packets. regular data packets.
This document updates [RFC5880] with respect to its descriptions on This document updates [RFC5880] with respect to its descriptions on
the BFD Echo function as follows. the BFD Echo function as follows.
* The 4th paragraph of Section 3.2 of [RFC5880] is updated as below: The 4th paragraph of Section 3.2 of [RFC5880] is updated as below:
* OLD TEXT
* An adjunct to both modes is the Echo function.
* NEW TEXT OLD TEXT
An adjunct to both modes is the Echo function.
* An adjunct to both modes is the Echo function, which can also be NEW TEXT
An adjunct to both modes is the Echo function, which can also be
running independently. running independently.
* OLD TEXT OLD TEXT
Since the Echo function is handling the task of detection, the
* Since the Echo function is handling the task of detection, the
rate of periodic transmission of Control packets may be reduced rate of periodic transmission of Control packets may be reduced
(in the case of Asynchronous mode) or eliminated completely (in (in the case of Asynchronous mode) or eliminated completely (in
the case of Demand mode). the case of Demand mode).
* NEW TEXT NEW TEXT
Since the Echo function is handling the task of detection, the
* Since the Echo function is handling the task of detection, the
rate of periodic transmission of Control packets may be reduced rate of periodic transmission of Control packets may be reduced
(in the case of Asynchronous mode) or eliminated completely (in (in the case of Asynchronous mode) or eliminated completely (in
the case of Demand mode). The Echo function may also be used the case of Demand mode). The Echo function may also be used
independently, with neither Asynchronous nor Demand mode. independently, with neither Asynchronous nor Demand mode.
* The 3rd and 9th paragraphs of Section 6.1 of [RFC5880] are updated The 3rd and 9th paragraphs of Section 6.1 of [RFC5880] are updated as
as below: below:
* OLD TEXT
* Once the BFD session is Up, a system can choose to start the Echo OLD TEXT
Once the BFD session is Up, a system can choose to start the Echo
function if it desires and the other system signals that it will function if it desires and the other system signals that it will
allow it. The rate of transmission of Control packets is allow it. The rate of transmission of Control packets is
typically kept low when the Echo function is active. typically kept low when the Echo function is active.
* NEW TEXT NEW TEXT
When a system is running with Asynchronous or Demand mode, once
* When a system is running with Asynchronous or Demand mode, once
the BFD session is Up, it can choose to start the Echo function if the BFD session is Up, it can choose to start the Echo function if
it desires and the other system signals that it will allow it. it desires and the other system signals that it will allow it.
The rate of transmission of Control packets is typically kept low The rate of transmission of Control packets is typically kept low
for Asynchronous mode or eliminated completely for Demand mode for Asynchronous mode or eliminated completely for Demand mode
when the Echo function is active. when the Echo function is active.
* OLD TEXT OLD TEXT
If the session goes Down, the transmission of Echo packets (if
* If the session goes Down, the transmission of Echo packets (if
any) ceases, and the transmission of Control packets goes back to any) ceases, and the transmission of Control packets goes back to
the slow rate. the slow rate.
* NEW TEXT NEW TEXT
In Asynchronous mode, if the session goes Down, the transmission
* In Asynchronous mode, if the session goes Down, the transmission
of Echo packets (if any) ceases, and the transmission of Control of Echo packets (if any) ceases, and the transmission of Control
packets goes back to the slow rate. Demand mode MUST NOT be packets goes back to the slow rate. Demand mode MUST NOT be
active if the session goes Down. active if the session goes Down.
* The 2nd paragraph of Section 6.4 of [RFC5880] is updated as below: The 2nd paragraph of Section 6.4 of [RFC5880] is updated as below:
* OLD TEXT
* When a system is using the Echo function, it is advantageous to OLD TEXT
When a system is using the Echo function, it is advantageous to
choose a sedate reception rate for Control packets, since liveness choose a sedate reception rate for Control packets, since liveness
detection is being handled by the Echo packets. This can be detection is being handled by the Echo packets. This can be
controlled by manipulating the Required Min RX Interval field (see controlled by manipulating the Required Min RX Interval field (see
section 6.8.3). section 6.8.3).
* NEW TEXT NEW TEXT
When a system is using the Echo function with Asynchronous mode,
* When a system is using the Echo function with Asynchronous mode,
it is advantageous to choose a sedate reception rate for Control it is advantageous to choose a sedate reception rate for Control
packets, since liveness detection is being handled by the Echo packets, since liveness detection is being handled by the Echo
packets. This can be controlled by manipulating the Required Min packets. This can be controlled by manipulating the Required Min
RX Interval field (see section 6.8.3). Note that a system RX Interval field (see section 6.8.3). Note that a system
operating in Demand mode would direct the remote system to cease operating in Demand mode would direct the remote system to cease
the periodic transmission of BFD Control packets, by setting the the periodic transmission of BFD Control packets, by setting the
Demand (D) bit in its BFD Control packets. Demand (D) bit in its BFD Control packets.
* The 2nd paragraph of Section 6.8 of [RFC5880] is updated as below: The 2nd paragraph of Section 6.8 of [RFC5880] is updated as below:
* OLD TEXT
* When a system is said to have "the Echo function active" it means OLD TEXT
When a system is said to have "the Echo function active" it means
that the system is sending BFD Echo packets, implying that the that the system is sending BFD Echo packets, implying that the
session is Up and the other system has signaled its willingness to session is Up and the other system has signaled its willingness to
loop back Echo packets. loop back Echo packets.
* NEW TEXT NEW TEXT
When a system in Asynchronous or Demand mode is said to have "the
* When a system in Asynchronous or Demand mode is said to have "the
Echo function active" it means that the system is sending BFD Echo Echo function active" it means that the system is sending BFD Echo
packets, implying that the session is Up and the other system has packets, implying that the session is Up and the other system has
signaled its willingness to loop back Echo packets. signaled its willingness to loop back Echo packets.
* The 7th paragraph of Section 6.8.3 of [RFC5880] is updated as The 7th paragraph of Section 6.8.3 of [RFC5880] is updated as below:
below:
* OLD TEXT
* When the Echo function is active, a system SHOULD set OLD TEXT
When the Echo function is active, a system SHOULD set
bfd.RequiredMinRxInterval to a value of not less than one second bfd.RequiredMinRxInterval to a value of not less than one second
(1,000,000 microseconds). This is intended to keep received BFD (1,000,000 microseconds). This is intended to keep received BFD
Control traffic at a negligible level, since the actual detection Control traffic at a negligible level, since the actual detection
function is being performed using BFD Echo packets. function is being performed using BFD Echo packets.
* NEW TEXT NEW TEXT
* When the Echo function is active with Asynchronous mode, a system When the Echo function is active with Asynchronous mode, a system
SHOULD set bfd.RequiredMinRxInterval to a value of not less than SHOULD set bfd.RequiredMinRxInterval to a value of not less than
one second (1,000,000 microseconds). This is intended to keep one second (1,000,000 microseconds). This is intended to keep
received BFD Control traffic at a negligible level, since the received BFD Control traffic at a negligible level, since the
actual detection function is being performed using BFD Echo actual detection function is being performed using BFD Echo
packets. While a system operating in Demand mode would not packets. While a system operating in Demand mode would not
receive BFD Control traffic. receive BFD Control traffic.
* The 1st and 2nd paragraphs of Section 6.8.9 of [RFC5880] are The 1st and 2nd paragraphs of Section 6.8.9 of [RFC5880] are updated
updated as below: as below:
* OLD TEXT
* BFD Echo packets MUST NOT be transmitted when bfd.SessionState is OLD TEXT
BFD Echo packets MUST NOT be transmitted when bfd.SessionState is
not Up. BFD Echo packets MUST NOT be transmitted unless the last not Up. BFD Echo packets MUST NOT be transmitted unless the last
BFD Control packet received from the remote system contains a BFD Control packet received from the remote system contains a
nonzero value in Required Min Echo RX Interval. nonzero value in Required Min Echo RX Interval.
* NEW TEXT NEW TEXT
When a system is using the Echo function with either Asynchronous
* When a system is using the Echo function with either Asynchronous
or Demand mode, BFD Echo packets MUST NOT be transmitted when or Demand mode, BFD Echo packets MUST NOT be transmitted when
bfd.SessionState is not Up, and BFD Echo packets MUST NOT be bfd.SessionState is not Up, and BFD Echo packets MUST NOT be
transmitted unless the last BFD Control packet received from the transmitted unless the last BFD Control packet received from the
remote system contains a nonzero value in Required Min Echo RX remote system contains a nonzero value in Required Min Echo RX
Interval. Interval.
* OLD TEXT OLD TEXT
BFD Echo packets MAY be transmitted when bfd.SessionState is Up.
* BFD Echo packets MAY be transmitted when bfd.SessionState is Up.
The interval between transmitted BFD Echo packets MUST NOT be less The interval between transmitted BFD Echo packets MUST NOT be less
than the value advertised by the remote system in Required Min than the value advertised by the remote system in Required Min
Echo RX Interval... Echo RX Interval...
* NEW TEXT NEW TEXT
When a system is using the Echo function with either Asynchronous
* When a system is using the Echo function with either Asynchronous
or Demand mode, BFD Echo packets MAY be transmitted when or Demand mode, BFD Echo packets MAY be transmitted when
bfd.SessionState is Up, and the interval between transmitted BFD bfd.SessionState is Up, and the interval between transmitted BFD
Echo packets MUST NOT be less than the value advertised by the Echo packets MUST NOT be less than the value advertised by the
remote system in Required Min Echo RX Interval... remote system in Required Min Echo RX Interval...
3. Unaffiliated BFD Echo Procedures 3. Unaffiliated BFD Echo Procedures
Device A Device B Device A Device B
BFD Enabled BFD Echo packets loopback BFD Enabled BFD Echo packets loopback
+--------+ BFD Echo session +--------+ +--------+ BFD Echo session +--------+
| A |--------------------------------| B | | A |--------------------------------| B |
| |Interface 1 Interface 1| | | |Interface 1 Interface 1| |
+--------+ +--------+ +--------+ +--------+
BFD is supported. BFD is not supported. BFD is supported. BFD is not supported.
Figure 1: Unaffiliated BFD Echo diagram Figure 1: Unaffiliated BFD Echo diagram
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The authors would like to acknowledge Ketan Talaulikar, Greg Mirsky The authors would like to acknowledge Ketan Talaulikar, Greg Mirsky
and Santosh Pallagatti for their careful review and very helpful and Santosh Pallagatti for their careful review and very helpful
comments. comments.
The authors would like to acknowledge Jeff Haas for his insightful The authors would like to acknowledge Jeff Haas for his insightful
review and very helpful comments. review and very helpful comments.
8. Contributors 8. Contributors
Liu Aihua ZTE Email: liu.aihua@zte.com.cn Liu Aihua
ZTE
Email: liu.aihua@zte.com.cn
Qian Xin ZTE Email: qian.xin2@zte.com.cn Qian Xin
ZTE
Email: qian.xin2@zte.com.cn
Zhao Yanhua ZTE Email: zhao.yanhua3@zte.com.cn Zhao Yanhua
ZTE
Email: zhao.yanhua3@zte.com.cn
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
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