Technical Summary
This document defines a mechanism to run BFD on Link Aggregation
Group (LAG) interfaces. It does so by running an independent
Asynchronous mode BFD session on every LAG member link.
This mechanism allows the verification of member link continuity,
either in combination with, or in absence of, LACP. It provides a
shorter detection time than what LACP offers. The continuity check
can also cover elements of layer 3 bidirectional forwarding.
This mechanism utilizes a well-known UDP port distinct from that of
single-hop BFD over IP. This new UDP port removes the ambiguity of
BFD over LAG packets from BFD over single-hop IP.
Working Group Summary
The blurred line between L2 and L3 initiated several interesting
discussions. Is it a layer violation for BFD operating at layer 3 to make
layer 2 decision? How does it interact with LACP? How does it influence
LAG member link usability?
The desire and need for rapid detection of LAG member link usability,
as well as similar solutions already implemented by multiple vendors,
resulted in consensus to push this technology forward. The WG was
satisfied with very careful wordings of the document to ensure that
solution does not tread on IEEE turf.
In addition, remote IP address discovery was a controversial topic.
There were multiple ideas to do this dynamically, on which the WG
couldn't reach consensus. Thus this aspect was taken out into a
separate draft.That spin-off draft died, since people lost interest due
to statically configuring remote IP address working good enough.
Document Quality
There are multiple implementations of the protocol. An event was
held to interoperate the implementations.
The document has been reviewed through the normal WG process.
No MIB Doctor, Media Type or other expert review been performed or
requested.
Personnel
Nobo Akiya is the document Shepherd.
Adrian Farrel is the responsible AD.