Understanding BGP Advertising Rules for Labeled and Unlabeled Routes with the Same AFI

When BGP receives a route to a prefix with the same AFI in both labeled and unlabeled forms, only one of these routes can be selected as the best route. The action taken after the best route is selected depends on whether the best route is labeled or unlabeled, and on what SAFI was previously negotiated with peers other than the one from which it received the best route. Table 93 lists the advertising action taken for the best route, whether labeled or unlabeled.

Table 93: Advertising Action Taken Following Best Route Selection

Best Route	SAFI Negotiated with Peer	Action Taken
Unlabeled	SAFI 1 and SAFI 4 (unlabeled and labeled)	Advertises unlabeled route.
Unlabeled	SAFI 1 (unlabeled)	Advertises unlabeled route.
Unlabeled	SAFI 4 (labeled)	Withdraws labeled route.
Labeled	SAFI 1 and SAFI 4 (unlabeled and labeled)	Advertises labeled route.
Labeled	SAFI 1 (unlabeled)	Withdraws unlabeled route.
Labeled	SAFI 4 (labeled)	Advertises labeled route.

BGP sends a route-refresh message for each SAFI that it has negotiated with a peer. For example, if a speaker has negotiated both SAFI 1 and SAFI 4 with a particular peer, then when you issue the clear ip bgp neighbor soft-in command, BGP sends two route-refresh messages to this neighbor, one for each SAFI.