Dell EMC SmartFabric OS10 User Guide Release 10.5.1

More path (Add-Path) reduces convergence times by advertising multiple paths to its peers for the same address prefix without replacing existing paths with new ones. By default, a BGP speaker advertises only the best path to its peers for a given address prefix.

If the best path becomes unavailable, the BGP speaker withdraws its path from its local router information base (RIB) and recalculates a new best path. This situation requires both IGP and BGP convergence and is a lengthy process. BGP add-path also helps switch over to the next new best path when the current best path is unavailable.

The Add-Path capability to advertise more paths is supported only on IBGP peers—it is not supported on EBGP peers or BGP peer groups.

Ignore router ID calculations

Avoid unnecessary BGP best path transitions between external paths under certain conditions. The bestpath router-id ignore command reduces network disruption that is caused by routing and forwarding plane changes and allows for faster convergence.