Configuring additional-paths and advertisement of additional-paths at peer group level

BGP additional-paths can be enabled for a specific peer group (neighbor) under a BGP address family. In addition, configuration options are available to control the additional-paths that are advertised by the neighbor.

1. From privileged EXEC mode, enter global configuration mode.
   

   device# configure terminal
   

2. Enable BGP routing.
   

   device(config)# router bgp
   

3. Create a peer group. The following example shows how to create a peer group named pg-1
   

   device(config-bgp)# neighbor pg-1 peer-group
   

4. Enter IPv4 unicast address family configuration mode.
   

   device(config-bgp)# address-family ipv4 unicast 
   

5. Enable additional-paths for the peer group.
   

   device(config-bgp-ipv4u)# neighbor pg-1 additional-paths receive send
   

   This example enables the capability to both receive and send additional-paths on peer group pg-1.

   

   Note

   Changes in the capability of receiving or sending additional-paths are reflected only after the BGP session is restarted.
6. Configure the additional-paths to be advertised by the peer group. The following example shows how to configure the advertisement of group-best paths.
   

   device(config-bgp-ipv4u)# neighbor pg-1 additional-paths advertise group-best
   

   Paths configured for advertisement to neighbors must be a subset of the paths previously configured by using the additional-paths select command under the IPv4 address family.

Example

The following example first shows how to configure group-best paths as candidates for selection as additional paths, under the IPv4 address family. It then shows how to enable receiving and sending additional-paths for peer group pg-1 and configures the advertisement of group-best paths for pg-1.

device# configure terminal
device(config)# router bgp
device(config-bgp)# address-family ipv4 unicast
device(config-bgp-ipv4u)# additional-paths select group-best
device(config-bgp-ipv4u)# exit

device(config-bgp)# neighbor pg-1 peer-group
device(config-bgp)# address-family ipv4 unicast 
device(config-bgp-ipv4u)# neighbor pg-1 additional-paths receive send
device(config-bgp-ipv4u)# neighbor pg-1 additional-paths advertise group-best