< draft-ietf-bfd-unaffiliated-echo-02.txt   draft-ietf-bfd-unaffiliated-echo-03.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 Intended status: Standards Track X. Min, Ed.
Expires: December 24, 2021 ZTE Corp. Expires: 28 July 2022 ZTE Corp.
R. Rahman R. Rahman
Individual Individual
R. Boddireddy R. Boddireddy
Juniper Networks Juniper Networks
June 22, 2021 24 January 2022
Unaffiliated BFD Echo Function Unaffiliated BFD Echo
draft-ietf-bfd-unaffiliated-echo-02 draft-ietf-bfd-unaffiliated-echo-03
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
function where the local system supports BFD but the neighboring where the local system supports BFD but the neighboring system does
system does not support BFD. not support BFD.
This document updates RFC 5880.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 December 24, 2021. This Internet-Draft will expire on 28 July 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 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.
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described in the Simplified 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 . . . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
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
faults in communication with adjacent devices. Measures can then be faults in communication with adjacent devices. Measures can then be
taken to promptly rectify the faults to ensure service continuity. taken to promptly rectify the faults to ensure service continuity.
BFD [RFC5880] is a low-overhead, short-duration method to detect BFD [RFC5880] is a low-overhead, short-duration method to detect
faults on the communication path between adjacent forwarding engines. faults on the communication path between adjacent forwarding engines.
The faults can be on interfaces, data link(s), and even the The faults can be on interfaces, data link(s), and even the
forwarding engines. It is a single, unified mechanism to monitor any forwarding engines. It is a single, unified mechanism to monitor any
media and protocol layers in real time. media and protocol layers in real time.
BFD defines an Asynchronous mode to satisfy various deployment BFD defines Asynchronous and Demand modes to satisfy various
scenarios. It also supports an Echo function to reduce the device deployment scenarios. It also supports an Echo function to reduce
requirement for BFD. When the Echo function is activated, the local the device requirement for BFD. When the Echo function is activated,
system sends BFD Echo packets and the remote system loops back the the local system sends BFD Echo packets and the remote system loops
received Echo packets through the forwarding path. If several back the received Echo packets through the forwarding path. If
consecutive BFD Echo packets are not received by the local system, several consecutive BFD Echo packets are not received by the local
then the BFD session is declared to be Down. system, then the BFD session is declared to be Down.
When using BFD Echo function, there are two typical scenarios as When using BFD Echo function, there are two typical scenarios as
below: below:
o Full BFD protocol capability with affiliated Echo function: This * Full BFD protocol capability with affiliated Echo function. This
scenario requires both the local device and the neighboring device scenario requires both the local device and the neighboring device
to support the full BFD protocol. to support the full BFD protocol.
o BFD Echo-Only function without full BFD protocol capability: This * BFD Echo-Only method without full BFD protocol capability. This
scenario requires only the local device to support sending and scenario requires only the local device to support sending and
demultiplexing BFD Control packets. demultiplexing BFD Control packets.
The latter scenario is referred to as Unaffiliated BFD Echo function The latter scenario is referred to as Unaffiliated BFD Echo in this
in this document. document.
Section 6.2.2 of [BBF-TR-146] describes one use case of the Section 6.2.2 of [BBF-TR-146] describes one use case of the
Unaffiliated BFD Echo function, and at least one more use case is Unaffiliated BFD Echo. Section 2 of [I-D.wang-bfd-one-arm-use-case]
known to be deployed. describes another use case of the Unaffiliated BFD Echo.
This document describes the use of the Unaffiliated BFD Echo function This document describes the use of the Unaffiliated BFD Echo over
over IPv4 and IPv6 for single IP hop. IPv4 and IPv6 for single IP hop.
1.1. Conventions Used in This Document 1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Updates to RFC 5880 2. Updates to RFC 5880
The Unaffiliated BFD Echo function described in this document reuses The Unaffiliated BFD Echo described in this document reuses the BFD
the BFD Echo function as described in [RFC5880] and [RFC5881], but Echo function as described in [RFC5880] and [RFC5881], but does not
does not require BFD Asynchronous mode. When using the Unaffiliated require BFD Asynchronous or Demand mode. When using the Unaffiliated
BFD Echo function, only the local system has the BFD protocol BFD Echo, only the local system has the BFD protocol enabled; the
enabled; the remote system just loops back the received BFD Echo remote system just loops back the received BFD Echo packets as
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.
o 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 * OLD TEXT
An adjunct to both modes is the Echo function. * An adjunct to both modes is the Echo function.
NEW TEXT * NEW TEXT
An adjunct or complement to both modes is the Echo function. * An adjunct to both modes is the Echo function, which can also be
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.
o 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 below: as below:
OLD TEXT * OLD TEXT
Once the BFD session is Up, a system can choose to start the Echo * 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. allow it. The rate of transmission of Control packets is
typically kept low when the Echo function is active.
NEW TEXT * NEW TEXT
When a system is running with Asynchronous mode, once the BFD * When a system is running with Asynchronous or Demand mode, once
session is Up, it can choose to start the Echo function if it the BFD session is Up, it can choose to start the Echo function if
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
for Asynchronous mode or eliminated completely for Demand mode
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. packets goes back to the slow rate. Demand mode MUST NOT be
active if the session goes Down.
o 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 * OLD TEXT
When a system is using the Echo function, it is advantageous to
* 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. detection is being handled by the Echo packets. This can be
controlled by manipulating the Required Min RX Interval field (see
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. packets. This can be controlled by manipulating the Required Min
RX Interval field (see section 6.8.3). Note that a system
operating in Demand mode would direct the remote system to cease
the periodic transmission of BFD Control packets, by setting the
Demand (D) bit in its BFD Control packets.
o 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 * OLD TEXT
When a system is said to have "the Echo function active" it means * 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.
o 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 * OLD TEXT
When the Echo function is active, a system SHOULD set * 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). (1,000,000 microseconds). This is intended to keep received BFD
Control traffic at a negligible level, since the actual detection
NEW TEXT function is being performed using BFD Echo packets.
When the Echo function is active with Asynchronous mode, a system * NEW TEXT
* 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). one second (1,000,000 microseconds). This is intended to keep
received BFD Control traffic at a negligible level, since the
actual detection function is being performed using BFD Echo
packets. While a system operating in Demand mode would not
receive BFD Control traffic.
o 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 as below: updated as below:
OLD TEXT * OLD TEXT
BFD Echo packets MUST NOT be transmitted when bfd.SessionState is
* 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
BFD Enabled BFD Echo packets loopback
+--------+ BFD Echo session +--------+
| A |--------------------------------| B |
| |Interface 1 Interface 1| |
+--------+ +--------+
BFD is supported. BFD is not supported.
Figure 1: Unaffiliated BFD Echo diagram
As shown in Figure 1, device A supports BFD, whereas device B does As shown in Figure 1, device A supports BFD, whereas device B does
not support BFD. Device A would send BFD Echo packets, and after not support BFD. Device A would send BFD Echo packets, and after
receiving the BFD Echo packets sent from device A, the one-hop-away receiving the BFD Echo packets sent from device A, the one-hop-away
BFD peer device B immediately loops them back by normal IP BFD peer device B immediately loops them back by normal IP
forwarding, this allows device A to rapidly detect a connectivity forwarding, this allows device A to rapidly detect a connectivity
loss to device B. Note that device B would not intercept any loss to device B. Note that device B would not intercept any
received BFD Echo packet or parse any BFD protocol field within the received BFD Echo packet or parse any BFD protocol field within the
BFD Echo packet. BFD Echo packet.
To rapidly detect any IP forwarding faults between device A and To rapidly detect any IP forwarding faults between device A and
device B, a BFD Echo session MUST be created at device A, and the BFD device B, a BFD Echo session MUST be created at device A, and the BFD
Echo session is RECOMMENDED to follow the BFD state machine defined Echo session MUST follow the BFD state machine defined in Section 6.2
in Section 6.2 of [RFC5880], except that the received state is not of [RFC5880], except that the received state is not sent but echoed
sent but echoed from the remote system, and AdminDown state is ruled from the remote system, and AdminDown state is ruled out because
out because AdminDown effectively means removal of BFD Echo session. AdminDown effectively means removal of BFD Echo session. In this
In this case, although BFD Echo packets are transmitted with case, although BFD Echo packets are transmitted with destination UDP
destination UDP port 3785 as defined in [RFC5881], the BFD Echo port 3785 as defined in [RFC5881], the BFD Echo packets sent by
packets sent by device A are BFD Control packets too, the looped BFD device A are BFD Control packets too, the looped BFD Echo packets
Echo packets back from device B would drive BFD state change at back from device B would drive BFD state change at device A,
device A, substituting the BFD Control packets sent from the BFD substituting the BFD Control packets sent from the BFD peer. Also
peer. Also note that when device A receives looped BFD Control note that when device A receives looped BFD Control packets, the
packets, the validation procedures of [RFC5880] are used. validation procedures of [RFC5880] are used.
Once a BFD Echo session is created at device A, it starts sending BFD Once a BFD Echo session is created at device A, it starts sending BFD
Echo packets, which SHOULD include a BFD Echo session demultiplexing Echo packets, which MUST include BFD Echo session demultiplexing
field, such as BFD "Your Discriminator" defined in [RFC5880] (BFD "My fields, such as BFD "Your Discriminator" defined in [RFC5880] (BFD
Discriminator" can be set to 0 to avoid confusion), except that "My Discriminator" can be set to 0 to avoid confusion), except for
device A can use IP source address or UDP source port to demultiplex BFD "Your Discriminator", device A can also use IP source address or
BFD Echo session, or there is only one BFD Echo session running at UDP source port to demultiplex BFD Echo session, or there is only one
device A. Device A would send BFD Echo packets with IP destination BFD Echo session running at device A. Device A would send BFD Echo
address destined for itself, such as the IP address of interface 1 of packets with IP destination address destined for itself, such as the
device A. All BFD Echo packets for the session MUST be sent with a IP address of interface 1 of device A. All BFD Echo packets for the
Time to Live (TTL) or Hop Limit value of 255. session MUST be sent with a Time to Live (TTL) or Hop Limit value of
255.
"Desired Min TX Interval" and "Required Min RX Interval" defined in
[RFC5880] may be populated with one second within the BFD Echo
packet, which however has no real application and would be ignored by
the receiver.
Considering the BFD peer wouldn't advertise "Required Min Echo RX
Interval" as defined in [RFC5880], the transmission interval for
sending BFD Echo packets MUST be provisioned at device A, how to make
sure the BFD peer is willing and able to loop back BFD Echo packets
sent with the provisioned transmission interval is outside the scope
of this document. Similar to what's specified in [RFC5880], the BFD
Echo session begins with the periodic, slow transmission of BFD Echo
packets, the slow transmission rate SHOULD be no less then one second
per packet, until the session is Up, after that the provisioned
transmission interval is applied, and reverting back to the slow rate
once the session goes Down. Considering the BFD peer wouldn't
advertise "Detect Mult" as defined in [RFC5880], the "Detect Mult"
for calculating the Detection Time MUST be provisioned at device A,
the Detection Time in device A is equal to the provisioned "Detect
Mult" multiplied by the provisioned transmission interval.
Device A Device B
BFD Enabled BFD Echo packets loopback Within the BFD Echo packet, the "Desired Min TX Interval" and
+--------+ BFD Echo session +---------+ "Required Min RX Interval" defined in [RFC5880] may be populated with
| A |--------------------------------| B | one second, which however has no real application and would be
| |Inf 1 Inf 1| | ignored by the receiver.
+--------+10.1.1.1/24 10.1.1.2/24+---------+
BFD is supported. BFD is not supported.
Figure 1: Unaffiliated BFD Echo diagram Considering that the BFD peer device B wouldn't advertise "Required
Min Echo RX Interval" as defined in [RFC5880], the transmission
interval for sending BFD Echo packets MUST be provisioned at device
A, how to make sure the BFD peer device B is willing and able to loop
back BFD Echo packets sent with the provisioned transmission interval
is outside the scope of this document. Similar to what's specified
in [RFC5880], the BFD Echo session begins with the periodic, slow
transmission of BFD Echo packets, the slow transmission rate SHOULD
be no less then one second per packet, until the session is Up, after
that the provisioned transmission interval is applied, and reverting
back to the slow rate once the session goes Down. Considering that
the BFD peer wouldn't advertise "Detect Mult" as defined in
[RFC5880], the "Detect Mult" for calculating the Detection Time MUST
be provisioned at device A, the Detection Time at device A is equal
to the provisioned "Detect Mult" multiplied by the provisioned
transmission interval.
4. Unaffiliated BFD Echo Applicability 4. Unaffiliated BFD Echo Applicability
Some devices that would benefit from the use of BFD may be unable to Some devices that would benefit from the use of BFD may be unable to
support the full BFD protocol. Examples of such devices include support the full BFD protocol. Examples of such devices include
servers running virtual machines, or Internet of Things (IoT) servers running virtual machines, or Internet of Things (IoT)
devices. The Unaffiliated BFD Echo function can be used when two devices. The Unaffiliated BFD Echo can be used when two devices are
devices are connected and only one of them supports the BFD protocol, connected and only one of them supports the BFD protocol, and the
and the other is capable of looping BFD Echo packets. other is capable of looping BFD Echo packets.
5. Security Considerations 5. Security Considerations
All Security Considerations from [RFC5880] and [RFC5881] apply. All Security Considerations from [RFC5880] and [RFC5881] apply.
Note that the Unaffiliated BFD Echo function prevents the use of Note that the Unaffiliated BFD Echo prevents the use of Unicast
Unicast Reverse Path Forwarding (URPF) [RFC3704] [RFC8704] in strict Reverse Path Forwarding (URPF) [RFC3704] [RFC8704] in strict mode.
mode.
As specified in Section 5 of [RFC5880], since BFD Echo packets may be As specified in Section 5 of [RFC5880], since BFD Echo packets may be
spoofed, some form of authentication SHOULD be included. Considering spoofed, some form of authentication SHOULD be included. Considering
the BFD Echo packets in this document are also BFD Control packets, the BFD Echo packets in this document are also BFD Control packets,
the "Authentication Section" as defined in [RFC5880] for BFD Control the "Authentication Section" as defined in [RFC5880] for BFD Control
packet is RECOMMENDED to be included within the BFD Echo packet. packet is RECOMMENDED to be included within the BFD Echo packet.
In order to mitigate the potential reflector attack by the remote In order to mitigate the potential reflector attack by the remote
attackers, or infinite loop of the BFD Echo packets, it's RECOMMENDED attackers, or infinite loop of the BFD Echo packets, it's RECOMMENDED
to put two requirements on the device looping BFD Echo packets, the to put two requirements on the device looping BFD Echo packets, the
skipping to change at page 9, line 7 skipping to change at page 9, line 23
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 Liu Aihua ZTE Email: liu.aihua@zte.com.cn
ZTE
Email: liu.aihua@zte.com.cn
Qian Xin Qian Xin ZTE Email: qian.xin2@zte.com.cn
ZTE
Email: qian.xin2@zte.com.cn
Zhao Yanhua Zhao Yanhua ZTE Email: zhao.yanhua3@zte.com.cn
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>.
skipping to change at page 9, line 48 skipping to change at page 10, line 10
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[BBF-TR-146] [BBF-TR-146]
Broadband Forum, "BBF Technical Report - Subscriber Broadband Forum, "BBF Technical Report - Subscriber
Sessions Issue 1", 2013, <https://www.broadband- Sessions Issue 1", 2013, <https://www.broadband-
forum.org/technical/download/TR-146.pdf>. forum.org/technical/download/TR-146.pdf>.
[I-D.wang-bfd-one-arm-use-case]
Wang, R., Cheng, W., Zhao, Y., and A. Liu, "Using One-Arm
BFD in Cloud Network", Work in Progress, Internet-Draft,
draft-wang-bfd-one-arm-use-case-00, 18 November 2019,
<https://www.ietf.org/archive/id/draft-wang-bfd-one-arm-
use-case-00.txt>.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March Networks", BCP 84, RFC 3704, DOI 10.17487/RFC3704, March
2004, <https://www.rfc-editor.org/info/rfc3704>. 2004, <https://www.rfc-editor.org/info/rfc3704>.
[RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced [RFC8704] Sriram, K., Montgomery, D., and J. Haas, "Enhanced
Feasible-Path Unicast Reverse Path Forwarding", BCP 84, Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
RFC 8704, DOI 10.17487/RFC8704, February 2020, RFC 8704, DOI 10.17487/RFC8704, February 2020,
<https://www.rfc-editor.org/info/rfc8704>. <https://www.rfc-editor.org/info/rfc8704>.
Authors' Addresses Authors' Addresses
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Email: chengweiqiang@chinamobile.com Email: chengweiqiang@chinamobile.com
Ruixue Wang Ruixue Wang
China Mobile China Mobile
Beijing Beijing
China China
Email: wangruixue@chinamobile.com Email: wangruixue@chinamobile.com
Xiao Min Xiao Min (editor)
ZTE Corp. ZTE Corp.
Nanjing Nanjing
China China
Email: xiao.min2@zte.com.cn Email: xiao.min2@zte.com.cn
Reshad Rahman Reshad Rahman
Individual Individual
Kanata Kanata
Canada Canada
Email: reshad@yahoo.com Email: reshad@yahoo.com
Raj Chetan Boddireddy Raj Chetan Boddireddy
Juniper Networks Juniper Networks
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