Cisco BGP Dynamic Neighbor

Cisco BGP Dynamic Neighbor

After an IPv4 subnet range is configured for a iBGP peer group and a TCP session is initiated
by another router which has an IP address in the IPv4 subnet range, a new BGP neighbor will be dynamically established as a member of that group.

 Here is the example:

router bgp 1
 bgp listen range 10.1.1.0/24 peer-group SPOKES
 bgp listen limit 1000
 neighbor SPOKES peer-group
 neighbor SPOKES remote-as 1
 neighbor SPOKES transport connection-mode passive
 neighbor SPOKES route-reflector-client



HUB#show ip bgp sum

Neighbor    V      AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
*10.1.1.3    4        1   70069   70100      160    0    0 5w0d            3
*10.1.1.4    4        1   80416   80459      160    0    0 5w1d            3
* Dynamically created based on a listen range command
Dynamically created neighbors: 2 Subnet ranges: 1
BGP peergroup DMVPN listen range group members:
  10.1.1.0/24
Total dynamically created neighbors: 2/(1000 max), Subnet ranges: 1