•
BFD Echo mode is not supported.
•
The mode change is applied only for new sessions. To apply mode change for existing sessions, delete
and then recreate the sessions.
•
A BFD session on the member interfaces can belong to only one mode (Cisco or IETF mode). Mix of
the modes within the same bundle is not supported.
•
All the bundles in the system can belong to only one mode at any single point in time.
BFD over Bundles CISCO/IETF Mode Support on a Per Bundle Basis
BFD over Bundle (BoB) mode is a standard based fast failure detection of link aggregation (LAG) member
links that is interoperable between different platforms. BoB support on a per bundle basis provides an option
to choose either Cisco or IETF standard per bundle, without necessitating reloads or process restarts across
various systems. The default is Cisco mode.
The global-level command available in previous releases to configure CISCO/IETF BoB over bundles is
deprecated from release 5.3.1 onwards. In order to ensure a smooth upgrade, Cisco recommends that you
configure the bundle at the interface level.
Note
•
The Cisco mode uses CDP MAC whereas IETF mode uses IANA assigned MAC.
•
Cisco BFD over Bundle sessions use destination UDP port: 3784, while IETF BFD over Bundle sessions
use destination UDP port: 6784.
Restrictions
These limitations apply for the BFD over Bundle Mode feature:
•
Supported only on Cisco ASR 9000 Enhanced Ethernet Line Card.
•
The BFD mode change (Cisco to IETF and vice-versa) goes through only when the BFD state for the
bundle is 'down' or 'BoB nonoperational.'
You can use the no bfd address-family ipv4 fast-detect command to make BoB
non-operational. You can also choose to configure a bundle to 'down' state by configuring
shutdown under that particular bundle.
Note
•
For a bundle to accept the new BFD mode change, you must bring down and then recreate the existing
BFD sessions.
•
BFD Echo mode is not supported in IETF BFD over Bundle (BoB) sessions.
BFD Dampening
Bidirectional Forwarding Detection (BFD) is a mechanism used by routing protocols to quickly realize and
communicate the reachability failures to their neighbors. When BFD detects a reachability status change of
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
252
Implementing BFD
BFD over Bundles CISCO/IETF Mode Support on a Per Bundle Basis
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