Steps to process  BGP Packet

When a Router receives route a BGP UPDATE packet that contains Network Layer Reachability Information (NLRI) Router processed the packet in below order:

– Step 1. BGP checks for the NLRI (prefix received) against any BGP inbound filter configured on the Router.

– Step 2. If the NLRI is not filtered, the prefix installed in the BGP table.

– Step 3. If the Router Routing Table already has the same prefix/prefix-length entry with a lower administrative distance (AD) BGP marks the route received with RIB-Failure.


In this example, routes and are received via BGP and are installed in the Routing Table.

The outputs show both routes in the BGP table with the use of the show ip bgp:


The Routing Table shows both routes with the command show ip route:


An example of RIB-failure can be seen because of static routes (with lower AD ) configured for the same prefixes


The outputs show static routes added to the configuration and how these override the BGP route in the Routing Table:


RIB-Failure routes marked as r in the BGP table. This is because the routes received via BGP are not in the Routing Table.


BGP still advertises networks in RIB-Failure state on Cisco Routers that run Cisco IOS. We can stop BGP forcefully to advertise RIB-Failure routes by below command:

bgp suppress-inactive 

Note: Only the networks in RIB-Failure condition which have a different next-hop in BGP than its same entry in Routing Table are suppressed with the bgp suppress-inactive command.


On Router INB_R2, routes are shown in the BGP table in RIB-Failure condition:


The reason is that Static Routes are configured:


  1. The Static Route for defines a next-hop to which differs from the next-hop received via BGP which is
  2. The Static Route for defines a next-hop which is equal to the next-hop received via BGP which is

To confirm if next-hop matches between rib-failure routes use below command :

show ip bgp rib-failure


Without bgp suppress-inactive command, even in RIB-Failure state, INB_R2 continues to advertise both networks to Router R4 via BGP since this is the default behavior.

In Router INB_R4, you can see both routes are received via BGP:


With bgp suppress-inactive added to the BGP configuration on Router INB_R2, the routes in RIB-Failure state and with RIB-NH Matches set to No are not advertised anymore:10

The next output shows that Router R4 does not receive the route via BGP since Router R2 does not advertise it anymore.11.PNG