Enabling BFD for an aggregation group

BFD provides link state monitoring and quick failure recovery for link aggregation groups. After you enable BFD on an aggregate interface, each Selected port in the aggregation group establishes a BFD session with its peer port. The failure recovery mechanism differs depending on the aggregation mode.

• BFD for static aggregation—When detecting link failure, BFD notifies the link aggregation feature that a peer port is unreachable, and the link aggregation feature places the local port in Unselected state. The BFD session on the failed link is retained, and the local port keeps sending BFD packets. When the local port receives BFD packets from the peer port again, BFD notifies the link aggregation feature that the peer port becomes reachable. The link aggregation feature then places the local port in Selected state.

• BFD for dynamic aggregation—When detecting link failure, BFD notifies the link aggregation feature that a peer port is unreachable. The BFD session on the failed link is removed, and the local port stops sending BFD packets. When the link is recovered and the local port becomes Selected again, the local port establishes a new BFD session with the peer port. BFD then notifies the link aggregation feature that the peer port becomes reachable.

For more information about BFD, see High Availability Configuration Guide.

When you enable BFD on an aggregate interface, follow these restrictions and guidelines:

• BFD is not supported if the aggregation group contains interfaces on a FIP-600 (JG360A) module.

• If you both specify a traffic processing slot and enable BFD on the aggregate interface, BFD sessions might flap when network congestion occurs.

• Make sure the source and destination IP addresses are consistent between the two ends of an aggregate link. For example, if you execute link-aggregation bfd ipv4 source 1.1.1.1 destination 2.2.2.2 at the local end, execute link-aggregation bfd ipv4 source 2.2.2.2 destination 1.1.1.1 at the peer end.

• The BFD parameters configured on the aggregate interface take effect on all its member interfaces' BFD sessions. BFD sessions for link aggregation do not support the echo packet mode or the Demand mode. For more information about BFD, see High Availability Configuration Guide.

• As a best practice, do not configure other features to collaborate with BFD on a BFD-enabled aggregate interface.

• Make sure the number of member ports in a BFD-enabled aggregation group is less than or identical to the number of BFD sessions supported by the device. If the aggregation group contains more member ports than the supported sessions, some Selected ports might change to the Unselected state.