draft-ietf-bfd-on-lags-04.txt   rfc7130.txt 
Network Working Group M. Bhatia, Ed. Internet Engineering Task Force (IETF) M. Bhatia, Ed.
Internet-Draft Alcatel-Lucent Request for Comments: 7130 Alcatel-Lucent
Intended status: Standards Track M. Chen, Ed. Category: Standards Track M. Chen, Ed.
Expires: June 21, 2014 Huawei Technologies ISSN: 2070-1721 Huawei Technologies
S. Boutros, Ed. S. Boutros, Ed.
M. Binderberger, Ed. M. Binderberger, Ed.
Cisco Systems Cisco Systems
J. Haas, Ed. J. Haas, Ed.
Juniper Networks Juniper Networks
December 18, 2013 February 2014
Bidirectional Forwarding Detection (BFD) on Link Aggregation Group (LAG) Bidirectional Forwarding Detection (BFD) on
Interfaces Link Aggregation Group (LAG) Interfaces
draft-ietf-bfd-on-lags-04
Abstract Abstract
This document defines a mechanism to run BFD on Link Aggregation This document defines a mechanism to run Bidirectional Forwarding
Group (LAG) interfaces. It does so by running an independent Detection (BFD) on Link Aggregation Group (LAG) interfaces. It does
Asynchronous mode BFD session on every LAG member link. so by running an independent Asynchronous mode BFD session on every
LAG member link.
This mechanism allows the verification of member link continuity, This mechanism allows the verification of member link continuity,
either in combination with, or in absence of, Link Aggregation either in combination with, or in absence of, Link Aggregation
Control Protocol (LACP). It provides a shorter detection time than Control Protocol (LACP). It provides a shorter detection time than
what LACP offers. The continuity check can also cover elements of what LACP offers. The continuity check can also cover elements of
layer 3 bidirectional forwarding. Layer 3 (L3) bidirectional forwarding.
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 Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
Task Force (IETF). Note that other groups may also distribute (IETF). It represents the consensus of the IETF community. It has
working documents as Internet-Drafts. The list of current Internet- received public review and has been approved for publication by the
Drafts is at http://datatracker.ietf.org/drafts/current/. Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
and may be updated, replaced, or obsoleted by other documents at any and how to provide feedback on it may be obtained at
time. It is inappropriate to use Internet-Drafts as reference http://www.rfc-editor.org/info/rfc7130.
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 21, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 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
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BFD on LAG member links . . . . . . . . . . . . . . . . . . . 5 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.1. Micro BFD session address family . . . . . . . . . . . . . 5 2. BFD on LAG Member Links . . . . . . . . . . . . . . . . . . . 3
2.2. Micro BFD session negotiation . . . . . . . . . . . . . . 5 2.1. Micro-BFD Session Address Family . . . . . . . . . . . . 4
2.3. Micro BFD session Ethernet details . . . . . . . . . . . . 6 2.2. Micro-BFD Session Negotiation . . . . . . . . . . . . . . 4
3. Interaction between LAG and BFD . . . . . . . . . . . . . . . 7 2.3. Micro-BFD Session Ethernet Details . . . . . . . . . . . 5
4. BFD on LAG member links and layer-3 applications . . . . . . . 7 3. Interaction between LAG and BFD . . . . . . . . . . . . . . . 6
5. Detecting a member link failure . . . . . . . . . . . . . . . 7 4. BFD on LAG Member Links and L3 Applications . . . . . . . . . 6
6. Security Consideration . . . . . . . . . . . . . . . . . . . . 8 5. Detecting a Member Link Failure . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. Contributing authors . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . 9
Appendix A. Considerations when using BFD on member links . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Appendix A. Considerations When Using BFD on Member Links . . . 10
1. Introduction 1. Introduction
The Bidirectional Forwarding Detection (BFD) protocol [RFC5880] The Bidirectional Forwarding Detection (BFD) protocol [RFC5880]
provides a mechanism to detect faults in the bidirectional path provides a mechanism to detect faults in the bidirectional path
between two forwarding engines, including interfaces, data link(s), between two forwarding engines, including interfaces, data links, and
and to the extent possible the forwarding engines themselves, with to the extent possible the forwarding engines themselves, with
potentially very low latency. The BFD protocol also provides a fast potentially very low latency. The BFD protocol also provides a fast
mechanism for detecting communication failures on any data links and mechanism for detecting communication failures on any data links and
the protocol can run over any media and at any protocol layer. the protocol can run over any media and at any protocol layer.
Link aggregation (LAG) as defined in [IEEE802.1AX] provides LAG, as defined in [IEEE802.1AX], provides mechanisms to combine
mechanisms to combine multiple physical links into a single logical multiple physical links into a single logical link. This logical
link. This logical link provides higher bandwidth and better link provides higher bandwidth and better resiliency, because if one
resiliency since if one of the physical member links fails the of the physical member links fails, the aggregate logical link can
aggregate logical link can continue to forward traffic over the continue to forward traffic over the remaining operational physical
remaining operational physical member links. member links.
Currently, the Link Aggregation Control Protocol (LACP) is used to Currently, the Link Aggregation Control Protocol (LACP) is used to
detect failures on a per physical member link. However, the use of detect failures on a per-physical-member link. However, the use of
BFD for failure detection would (1) provide a faster detection (2) BFD for failure detection would (1) provide a faster detection, (2)
provide detection in the absence of LACP (3) and would be able to provide detection in the absence of LACP, and (3) would be able to
verify the ability for each member link to be able to forward L3 verify the ability for each member link to be able to forward L3
packets. packets.
Running a single BFD session over the aggregation without internal Running a single BFD session over the aggregation without internal
knowledge of the member links would make it impossible for BFD to knowledge of the member links would make it impossible for BFD to
guarantee detection of the physical member link failures. guarantee detection of the physical member link failures.
The goal is to verify link Continuity for every member link. This The goal is to verify link Continuity for every member link. This
corresponds to [RFC5882], section 7.3. corresponds to [RFC5882], Section 7.3.
The approach taken in this document is to run a Asynchronous mode BFD The approach taken in this document is to run an Asynchronous mode
session over each LAG member link and make BFD control whether the BFD session over each LAG member link and make BFD control whether
LAG member link should be part of the L2 Loadbalance table of the LAG the LAG member link should be part of the L2 load-balancing table of
interface in the presence or the absence of LACP. the LAG interface in the presence or the absence of LACP.
This document describes how to establish an Asynchronous mode BFD This document describes how to establish an Asynchronous mode BFD
session per physical LAG member link of the LAG interface. session per physical LAG member link of the LAG interface.
While there are native Ethernet mechanisms to detect failures While there are native Ethernet mechanisms to detect failures
(802.1ax, .3ah) that could be used for LAG, the solution defined in (802.1ax, .3ah) that could be used for LAG, the solution defined in
this document enables operators who have already deployed BFD over this document enables operators who have already deployed BFD over
different technologies (e.g. IP, MPLS) to use a common failure different technologies (e.g., IP, MPLS) to use a common failure
detection mechanism. detection mechanism.
2. BFD on LAG member links 1.1. 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].
2. BFD on LAG Member Links
The mechanism defined for a fast detection of LAG member link failure The mechanism defined for a fast detection of LAG member link failure
is to run Asynchronous mode BFD sessions on every LAG member link. is to run Asynchronous mode BFD sessions on every LAG member link.
We call these per LAG member link BFD sessions "micro BFD sessions" We call these per-LAG-member-link BFD sessions "micro-BFD sessions"
in the remainder of this document. in the remainder of this document.
2.1. Micro BFD session address family 2.1. Micro-BFD Session Address Family
Member link micro BFD sessions, when using IP/UDP encapsulation, can Member link micro-BFD sessions, when using IP/UDP encapsulation, can
use IPv4 or IPv6 addresses. Two micro sessions MAY exist per member use IPv4 or IPv6 addresses. Two micro-BFD sessions MAY exist per
link, one IPv4, another IPv6. When an address family is used on one member link: one IPv4 another IPv6. When an address family is used
member link then it MUST be used on all member links of the on one member link, then it MUST be used on all member links of the
particular LAG. particular LAG.
2.2. Micro BFD session negotiation 2.2. Micro-BFD Session Negotiation
A single micro BFD session for every enabled address family runs on A single micro-BFD session for every enabled address family runs on
each member link of the LAG. The micro BFD session's negotiation each member link of the LAG. The micro-BFD session's negotiation
MUST follow the same procedures defined in [RFC5880] and [RFC5881]. MUST follow the same procedures defined in [RFC5880] and [RFC5881].
Only Asynchronous mode BFD is considered in this document; the use of Only Asynchronous mode BFD is considered in this document; the use of
the BFD echo function is outside the scope of this document. At the BFD echo function is outside the scope of this document. At
least one system MUST take the Active role (possibly both). The least one system MUST take the Active role (possibly both). The
micro BFD sessions on the member links are independent BFD sessions: micro-BFD sessions on the member links are independent BFD sessions.
They use their own unique local discriminator values, maintain their They use their own unique local discriminator values, maintain their
own set of state variables and have their own independent state own set of state variables, and have their own independent state
machines. Timer values MAY be different, even among the micro BFD machines. Timer values MAY be different, even among the micro-BFD
sessions belonging to the same aggregation, although it is expected sessions belonging to the same aggregation, although it is expected
that micro BFD sessions belonging to the same aggregation will use that micro-BFD sessions belonging to the same aggregation will use
the same timer values. the same timer values.
The demultiplexing of a received BFD packet is solely based on the The demultiplexing of a received BFD packet is solely based on the
Your Discriminator field, if this field is nonzero. For the initial Your Discriminator field, if this field is nonzero. For the initial
Down BFD packets of a BFD session this value MAY be zero. In this Down BFD packets of a BFD session, this value MAY be zero. In this
case demultiplexing MUST be based on some combination of other fields case, demultiplexing MUST be based on some combination of other
which MUST include the interface information of the member link and fields that MUST include the interface information of the member link
the destination UDP port of the received BFD packet. and the destination UDP port of the received BFD packet.
The procedure for the Reception of BFD Control Packets in Section The procedure for the reception of BFD control packets in
6.8.6 of [RFC5880] is amended as follows for per LAG member link Section 6.8.6 of [RFC5880] is amended as follows for per-LAG-member-
micro BFD sessions: "If the Your Discriminator field is non-zero and link micro-BFD sessions:
a micro BFD over LAG session is found, the interface on which the
micro BFD control packet arrived on MUST correspond to the interface
associated with that session."
This document defines the BFD Control packets for each micro BFD If the Your Discriminator field is nonzero and a micro-BFD over a
LAG session is found, the interface on which the micro-BFD control
packet arrived MUST correspond to the interface associated with
that session.
This document defines the BFD control packets for each micro BFD
session to be IP/UDP encapsulated as defined in [RFC5881], but with a session to be IP/UDP encapsulated as defined in [RFC5881], but with a
new UDP destination port 6784. new UDP destination port 6784.
The new UDP port removes the ambiguity of BFD over LAG packets from The new UDP port removes the ambiguity of BFD over LAG packets from
BFD over single-hop IP. An example is (mis-)configuring a LAG with BFD over single-hop IP. An example is (mis-)configuring a LAG with
micro BFD sessions on one side but using a [RFC5881] BFD session for micro-BFD sessions on one side but using a [RFC5881] BFD session for
the LAG (treated as a single interface) on the opposite side. the LAG (treated as a single interface) on the opposite side.
The procedures in this document MUST be used for BFD messages The procedures in this document MUST be used for BFD messages
addressed to port 6784 and MUST NOT be used for others ports assigned addressed to port 6784 and MUST NOT be used for others ports assigned
in RFCs described other BFD modes. in RFCs describing other BFD modes.
Control packets use a destination IP address that is configured on Control packets use a destination IP address that is configured on
the peer system and can be reached via the LAG interface. the peer system and can be reached via the LAG interface.
Implementations may range from explicitly configuring IP addresses Implementations may range from explicitly configuring IP addresses
for the BFD sessions to out-of-band methods for learning the for the BFD sessions to out-of-band methods for learning the
destination IP address. The details are outside the scope of this destination IP address. The details are outside the scope of this
document. document.
2.3. Micro BFD session Ethernet details 2.3. Micro-BFD Session Ethernet Details
On Ethernet-based LAG member links the destination MAC is the On Ethernet-based LAG member links, the destination Media Access
dedicated multicast MAC address 01-00-5E-90-00-01 to be the immediate Control (MAC) is the dedicated multicast MAC address
next hop. This dedicated MAC address MUST be used for the initial 01-00-5E-90-00-01 to be the immediate next hop. This dedicated MAC
BFD packets of a micro BFD session when in the Down/AdminDown and address MUST be used for the initial BFD packets of a micro-BFD
Init state. When a micro BFD session is changing into Up state then session when in the Down/AdminDown and Init states. When a micro-BFD
the first bfd.DetectMult packets with Up state MUST be sent with the session is changing into the Up state, the first bfd.DetectMult
dedicated MAC. For the following BFD packets with Up state the packets in the Up state MUST be sent with the dedicated MAC. For BFD
source MAC address from the received BFD packets for the session MAY packets in the Up state following the first bfd.DetectMult packets,
be used instead of the dedicated MAC. the source MAC address from the received BFD packets for the session
MAY be used instead of the dedicated MAC.
All implementations MUST be able to send and receive BFD packets in All implementations MUST be able to send and receive BFD packets in
Up state using the dedicated MAC address. Implementations supporting Up state using the dedicated MAC address. Implementations supporting
both, sending BFD Up packets with the dedicated and the received MAC, both, sending BFD Up packets with the dedicated and the received MAC,
need to offer means to control the behaviour. need to offer means to control the behaviour.
On Ethernet-based LAG member links the source MAC SHOULD be the MAC On Ethernet-based LAG member links, the source MAC SHOULD be the MAC
address of the member link transmitting the packet. address of the member link transmitting the packet.
This mechanism helps to reduce the use of additional MAC addresses, This mechanism helps to reduce the use of additional MAC addresses,
which reduces the required resources on the Ethernet hardware on the which reduces the required resources on the Ethernet hardware on the
receiving member link. receiving member link.
Micro BFD packets SHOULD always be sent untagged. However, when the Micro-BFD packets SHOULD always be sent untagged. However, when the
LAG is operating in the context of IEEE 802.1q or IEEE 802.qinq, the LAG is operating in the context of IEEE 802.1q or IEEE 802.qinq, the
micro BFD packets may either be untagged or sent with a vlan tag of micro-BFD packets may either be untagged or be sent with a vlan tag
Zero (802.1p priority tagged). Implementations compliant to this of Zero (802.1p priority tagged). Implementations compliant with
standard MUST be able to receive both untagged and 802.1p priority this standard MUST be able to receive both untagged and 802.1p
tagged micro BFD packets. priority tagged micro-BFD packets.
3. Interaction between LAG and BFD 3. Interaction between LAG and BFD
The micro BFD sessions for a particular LAG member link MUST be The micro-BFD sessions for a particular LAG member link MUST be
requested when a member link state is either Distributing or Standby. requested when a member link state is either Distributing or Standby.
The sessions MUST be deleted when the member link is neither in The sessions MUST be deleted when the member link is in neither
Distributing nor in Standby state anymore. Distributing nor Standby state anymore.
BFD is used to control if the load balance algorithm is able to BFD is used to control if the load-balancing algorithm is able to
select a particular LAG member link. In other words, even when Link select a particular LAG member link. In other words, even when Link
Aggregation Control Protocol (LACP) is used and considers the member Aggregation Control Protocol (LACP) is used and considers the member
link to be ready to forward traffic, the member link MUST NOT be used link to be ready to forward traffic, the member link MUST NOT be used
by the load balancer until all the micro BFD sessions of the by the load balancer until all the micro-BFD sessions of the
particular member link are in Up state. particular member link are in Up state.
In case an implementation has separate load balance tables for IPv4 In case an implementation has separate load-balancing tables for IPv4
and IPv6 and if both an IPv4 and IPv6 micro session exist for a and IPv6 and if both an IPv4 and IPv6 micro-BFD session exist for a
member link then an implementation MAY enable the member link in the member link, then an implementation MAY enable the member link in the
load balance algorithm based on the BFD session with a matching load-balancing algorithm based on the BFD session with a matching
address family alone. address family alone.
An exception is the BFD packet itself. Implementations MAY receive An exception is the BFD packet itself. Implementations MAY receive
and transmit BFD packets via the Aggregator's MAC service interface and transmit BFD packets via the Aggregator's MAC service interface,
independent of the session state. independent of the session state.
4. BFD on LAG member links and layer-3 applications 4. BFD on LAG Member Links and L3 Applications
The mechanism described in this document is likely to be used by The mechanism described in this document is likely to be used by
modules managing Interfaces or Link aggregation groups and thus modules managing Interfaces or LAGs and, thus, managing the member
managing the member links of a LAG. Typical layer 3 protocols like links of a LAG. Typical L3 protocols like OSPF do not have an
OSPF do not have an insight into the LAG and treat it as one bigger insight into the LAG and treat it as one bigger interface. The
interface. The signaling from micro sessions to layer 3 protocols is signaling from micro sessions to L3 protocols is effectively done by
effectively done by the impact of BFD micro sessions on the load the impact of micro-BFD sessions on the load-balancing table and the
balance table and the Interface/LAG managing module's potential Interface/LAG managing module's potential decision to shut down the
decision to shut down the LAG. An active method to test the impact LAG. An active method to test the impact of micro-BFD sessions is
of micro sessions is for layer 3 protocols to request a single BFD for L3 protocols to request a single BFD session per LAG.
session per LAG.
5. Detecting a member link failure 5. Detecting a Member Link Failure
When a micro BFD session goes down then this member link MUST be When a micro-BFD session goes down, this member link MUST be taken
taken out of the LAG L2 load balance table(s). out of the LAG load-balancing table(s).
In case an implementation has separate load balance tables for IPv4 In case an implementation has separate load-balancing tables for IPv4
and IPv6 then if both an IPv4 and IPv6 micro session exist for a and IPv6, then if both an IPv4 and IPv6 micro-BFD session exist for a
member link an implementation MAY remove the member link only from member link, an implementation MAY remove the member link only from
the load balance table that matches the address family of the failing the load-balancing table that matches the address family of the
BFD session. For example the IPv4 micro session fails but the IPv6 failing BFD session. For example, the IPv4 micro-BFD session fails
micro session stays Up then the member link MAY be removed from only but the IPv6 micro-BFD session stays Up, then the member link MAY be
the IPv4 load balance table; the link MAY remain in the IPv6 load removed from only the IPv4 load balance table; the link MAY remain in
balancing table. Alternatively, the member link may be removed from the IPv6 load-balancing table. Alternatively, the member link may be
both the IPv4 and IPv6 load balancing tables. This decision is an removed from both the IPv4 and IPv6 load-balancing tables. This
implementation detail. decision is an implementation detail.
6. Security Consideration 6. Security Considerations
This document does not introduce any additional security issues and This document does not introduce any additional security issues and
the security mechanisms defined in [RFC5880] apply in this document. the security mechanisms defined in [RFC5880] apply in this document.
7. IANA Considerations 7. IANA Considerations
IANA assigned a dedicated MAC address 01-00-5E-90-00-01 (see IANA assigned a dedicated MAC address 01-00-5E-90-00-01 (see
[RFC7042]) as well as UDP port 6784 for Bidirectional Forwarding [RFC7042]) as well as UDP port 6784 for Bidirectional Forwarding
Detection (BFD) on Link Aggregation Group (LAG) Interfaces. IANA is Detection (BFD) on Link Aggregation Group (LAG) Interfaces. IANA has
requested to change the reference to [RFC-to-be]. changed the reference to [RFC7130].
IANA is requested to change the registry for port 6784 to show the IANA has changed the registry for port 6784 to show the Assignee as
Assignee as [IESG] and the Contact as [BFD Chairs]. The expansion of [IESG] and the Contact as [BFD_Chairs]. The expansion of
[BFD Chairs] should be shown as "mailto:bfd-chairs@tools.ietf.org". [BFD_Chairs] is shown as "mailto:bfd-chairs@tools.ietf.org". IANA
IANA is requested to change the reference to [RFC-to-be]. has changed the reference to [RFC7130].
8. Acknowledgements 8. Acknowledgements
We would like to thank Dave Katz, Alexander Vainshtein, Greg Mirsky We would like to thank Dave Katz, Alexander Vainshtein, Greg Mirsky,
and Jeff Tantsura for their comments. and Jeff Tantsura for their comments.
The initial event to start the current discussion was the The initial event to start the current discussion was the
distribution of draft-chen-bfd-interface-00. distribution of "Bidirectional Forwarding Detection (BFD) for
Interface" (July 2011).
9. Contributing authors 9. Contributors
Paul Hitchen Paul Hitchen
BT BT
Email: paul.hitchen@bt.com EMail: paul.hitchen@bt.com
George Swallow George Swallow
Cisco Systems Cisco Systems
Email: swallow@cisco.com EMail: swallow@cisco.com
Wim Henderickx Wim Henderickx
Alcatel-Lucent Alcatel-Lucent
Email: wim.henderickx@alcatel-lucent.com EMail: wim.henderickx@alcatel-lucent.com
Nobo Akiya Nobo Akiya
Cisco Systems Cisco Systems
Email: nobo@cisco.com EMail: nobo@cisco.com
Neil Ketley Neil Ketley
Cisco Systems Cisco Systems
Email: nketley@cisco.com EMail: nketley@cisco.com
Carlos Pignataro Carlos Pignataro
Cisco Systems Cisco Systems
Email: cpignata@cisco.com EMail: cpignata@cisco.com
Nitin Bahadur Nitin Bahadur
Bracket Computing Bracket Computing
Email: nitin@brkt.com EMail: nitin@brkt.com
Zuliang Wang Zuliang Wang
Huawei Technologies Huawei Technologies
Email: liang_tsing@huawei.com EMail: liang_tsing@huawei.com
Liang Guo Liang Guo
China Telecom China Telecom
Email: guoliang@gsta.com EMail: guoliang@gsta.com
Jeff Tantsura Jeff Tantsura
Ericsson Ericsson
Email: jeff.tantsura@ericsson.com EMail: jeff.tantsura@ericsson.com
10. References 10. References
10.1. Normative References 10.1. 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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010. (BFD)", RFC 5880, June 2010.
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June
June 2010. 2010.
[RFC5882] Katz, D. and D. Ward, "Generic Application of [RFC5882] Katz, D. and D. Ward, "Generic Application of
Bidirectional Forwarding Detection (BFD)", RFC 5882, Bidirectional Forwarding Detection (BFD)", RFC 5882, June
June 2010. 2010.
10.2. Informative References 10.2. Informative References
[IEEE802.1AX] [IEEE802.1AX]
IEEE Std. 802.1AX, "IEEE Standard for Local and IEEE Std. 802.1AX, "IEEE Standard for Local and
metropolitan area networks - Link Aggregation", metropolitan area networks - Link Aggregation", November
November 2008. 2008.
[RFC7042] Eastlake, D. and J. Abley, "IANA Considerations and IETF [RFC7042] Eastlake, D. and J. Abley, "IANA Considerations and IETF
Protocol and Documentation Usage for IEEE 802 Parameters", Protocol and Documentation Usage for IEEE 802 Parameters",
BCP 141, RFC 7042, October 2013. BCP 141, RFC 7042, October 2013.
Appendix A. Considerations when using BFD on member links Appendix A. Considerations When Using BFD on Member Links
If the BFD over LAG feature were provisioned on an aggregated link If the BFD-over-LAG feature were provisioned on an aggregated link
member after the link was already active within a LAG, BFD session member after the link was already active within a LAG, BFD session
state should not influence the load balance algorithm until the BFD state should not influence the load-balancing algorithm until the BFD
session state transitions to Up. If the BFD session never session state transitions to Up. If the BFD session never
transitions to Up but the LAG becomes inactive, the previously transitions to Up but the LAG becomes inactive, the previously
documented procedures would then normally apply. documented procedures would then normally apply.
This procedure ensures that the sequence of events - enabling the LAG This procedure ensures that the sequence of events -- enabling the
and enabling BFD on the LAG - has no impact on the forwarding LAG and enabling BFD on the LAG -- has no impact on the forwarding
service. service.
If the BFD over LAG feature was deprovisioned on an aggregate link If the BFD-over-LAG feature were deprovisioned on an aggregate link
member while the associated micro BFD session was in Up state, BFD member while the associated micro-BFD session was in Up state, BFD
should transition its state to AdminDown and should attempt to should transition its state to AdminDown and should attempt to
communicate this state change to the peer. communicate this state change to the peer.
If the local or the remote state of a micro BFD session is AdminDown If the local or the remote state of a micro-BFD session is AdminDown,
the system should not indicate a connectivity failure to any client the system should not indicate a connectivity failure to any client
and should not remove the particular LAG member link from forwarding. and should not remove the particular LAG member link from forwarding.
This behaviour is independent from the use of Link Aggregation This behaviour is independent from the use of Link Aggregation
Control Protocol (LACP) for the LAG. Control Protocol (LACP) for the LAG.
When traffic is forwarded across a link while the corresponding micro When traffic is forwarded across a link while the corresponding
BFD session is not in Up state an implementation may use a micro-BFD session is not in Up state, an implementation may use a
configurable timeout value after which the BFD session must have configurable timeout value after which the BFD session must have
reached Up state or otherwise the link is taken out of forwarding. reached Up state otherwise the link is taken out of forwarding.
When such timeout values exist then the configuration must allow to When such timeout values exist, the configuration must allow the
turn off the timeout function. ability to turn off the timeout function.
The configurable timeout value shall ensure that a LAG is not The configurable timeout value shall ensure that a LAG is not
remaining forever in an "inconsistent" state where forwarding occurs remaining forever in an "inconsistent" state where forwarding occurs
on a link with no confirmation from the micro BFD session that the on a link with no confirmation from the micro-BFD session that the
link is healthy. link is healthy.
Note that if one device is not operating a micro BFD session on a Note that if one device is not operating a micro-BFD session on a
link, while the other device is and perceives the session to be Down, link, while the other device is and perceives the session to be Down,
this will result in the two devices having a different view of the this will result in the two devices having a different view of the
status of the link. This would likely lead to traffic loss across status of the link. This would likely lead to traffic loss across
the LAG. The use of another protocol to bootstrap BFD can detect the LAG. The use of another protocol to bootstrap BFD can detect
such mismatched config, since the side that's not configured can send such mismatched config, since the side that's not configured can send
a rejection error. Such bootstrapping mechanisms are outside the a rejection error. Such bootstrapping mechanisms are outside the
scope of this document. scope of this document.
Authors' Addresses Authors' Addresses
Manav Bhatia (editor) Manav Bhatia (editor)
Alcatel-Lucent Alcatel-Lucent
Bangalore 560045 Bangalore 560045
India India
Email: manav.bhatia@alcatel-lucent.com EMail: manav.bhatia@alcatel-lucent.com
Mach(Guoyi) Chen (editor) Mach(Guoyi) Chen (editor)
Huawei Technologies Huawei Technologies
Q14 Huawei Campus, No. 156 Beiqing Road, Hai-dian District Q14 Huawei Campus, No. 156 Beiqing Road, Hai-dian District
Beijing 100095 Beijing 100095
China China
Email: mach@huawei.com EMail: mach@huawei.com
Sami Boutros (editor) Sami Boutros (editor)
Cisco Systems Cisco Systems
Email: sboutros@cisco.com EMail: sboutros@cisco.com
Marc Binderberger (editor) Marc Binderberger (editor)
Cisco Systems Cisco Systems
Email: mbinderb@cisco.com EMail: mbinderb@cisco.com
Jeffrey Haas (editor) Jeffrey Haas (editor)
Juniper Networks Juniper Networks
Email: jhaas@juniper.net EMail: jhaas@juniper.net
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