What needs to be done if changes in BGP are not taking effect

Routing policies for a peer include all the configurations such as route-map, distribute-list, prefix-list, & filter-list that may impact inbound or outbound routing table updates. Whenever there is a change in the routing policy, the BGP session must be cleared, or reset, for the new policy to take effect.

There are two types of reset, hard reset and soft reset.

Clearing a BGP session using a hard reset invalidates the cache and results in a negative impact on the operation of networks as the information in the cache becomes unavailable.

Soft reset is recommended because it allows routing tables to be reconfigured and activated without clearing the BGP session. Soft reset is done on a per-neighbor basis. There are two types of soft reset:

When soft reset is used to generate inbound updates from a neighbor, it is called dynamic inbound soft reset.

When soft reset is used to send a new set of updates to a neighbor, it is called outbound soft reset.

In order to perform a soft reset for inbound routing table updates issue the “neighbor soft-reconfiguration” command under BGP process

If even after soft reset BGP changes are not taking effect follow the below steps

clear ip bgp A.B.C.D soft out –> When you make changes in outbound policy

and use

clear ip bgp A.B.C.D soft in –> When you make changes in inbound policy .

If still it’s not working then you should try the “clear ip bgp *” use this command with caution as this command will reset all neigbourship more over it like BGP will create routing table from scratch. This is as good as rebooting the router.