BGP peer group reduces the amount of system resources (CPU and memory) necessary in an update generation. In addition, a BGP peer group also simplifies the BGP configuration of peers. It is recommended that administrator group together neighbors with identical outbound announcement policies.
Neighbors configured in different address-families could not belong to the same peer group. Neighbors configured in the same autonomous system and in different autonomous system could not belong to the same peer group.
The figure shown below depicts the topology setup used for this configuration.
Figure 1. Configuration and Testing BGP Peer
Groups
Use the following commands to configure BGP routing.
- Execute the following commands to configure BGP Peer group.
Perform the following:
Configure Peer Group in Router ISS
- Enter the Global Configuration Mode.
iS5comm# configure terminal- Enable BGP in R1.
iS5comm(config)# router bgp 100- Configure an internal peer group pgrp1 in R2.
iS5comm(config-router)# neighbor pgrp1 peer-groupiS5comm(config-router)# neighbor pgrp1 remote-as 100- Configure maximum prefix limit for peer group.
iS5comm(config-router)# neighbor pgrp1 maximum-prefix 125- Configure keep alive time for peer group.
iS5comm(config-router)# neighbor pgrp1 timers keepalive 35- Configure peer group as passive.
iS5comm(config-router)# neighbor pgrp1 transport connection-mode passive- Configure advertisement interval for the peer group.
iS5comm(config-router)# neighbor pgrp1 advertisement-interval 15- Configure dampening for the peer group
iS5comm(config-router)# neighbor pgrp1damp-peer-oscillations- Configure route reflection for the peer group.
iS5comm(config-router)# neighbor pgrp1route-reflector-client- Configure ISS1, ISS3, ISS4 as internal peer of ISS2.
iS5comm(config-router)# neighbor 14.0.0.1 peer-group pgrp1iS5comm(config-router)# neighbor 15.0.0.2 peer-group pgrp1iS5comm(config-router)# neighbor 16.0.0.2 peer-group pgrp1 - To configure internal BGP sessions:
Execute the following commands:
Configure internal BGP session inISS1
- Enter the Global Configuration Mode.
iS5comm# configure terminal- Enable BGP in ISS1.
iS5comm(config)# router bgp 100- Configure an internal BGP session with ISS2.
iS5comm(config-router)# neighbor 14.0.0.2 remote-as 100Configure internal BGP session in ISS3
- Enter the Global Configuration Mode.
iS5comm# configure terminal- Enable BGP in ISS3.
iS5comm(config)# router bgp 100- Configure an internal BGP session with ISS2.
iS5comm(config-router)# neighbor 15.0.0.1 remote-as 100Configure internal BGP session in ISS4
- Enter the Global Configuration Mode.
iS5comm# configure terminal- Enable BGP in ISS4.
iS5comm(config)# router bgp 100- Configure an internal BGP session with ISS2.
iS5comm(config-router)# neighbor 16.0.0.1 remote-as 100 - ISS2: View the BGP peer
group configurations.
Type the following:
- R1: View the bgp summary information.
iS5comm# show ip bgp peer-groupBGP peer-group is pgrp1, Remote AS 100
BGP Version 0
For address family: IPv4 Unicast
BGP neighbor is pgrp1,peer-group internal, members:
14.0.0.1 15.0.0.2 16.0.0.2
BGP Maximum Prefix Limit: 125
Connect Retry Count: 5
Peer Passive :Enabled
Damp Peer oscillatios:Enabled
Rfl Status :Client
In Route Map: -
Out Route Map: -
- ISS2: View the BGP summary
information using ‘show ip bgp summary’.
Type the following:
- R1: View the bgp summary information.
iS5comm# show ip bgp summaryBGP router identifier is 12.0.0.1, local AS number 100
BGP table version is 0
Neighbor Version AS MsgRcvd MsgSent Up/Down State/PfxRcd
-------- ------- -- ------- ------- ------- ------------
14.0.0.1 4 100 5 5 00:00:1:48 Established
15.0.0.2 4 100 5 5 00:00:1:48 Established
16.0.0.2 4 100 4 4 00:00:1:21 Established
- ISS2: View the BGP neighbor configurations.
Type the following:
- R1: View the bgp summary information.
iS5comm# show ip bgp neighborBGP neighbor is 14.0.0.1, remote AS 100, internal link
BGP version 4, remote router ID 14.0.0.1
BGP state = Established, up for 1 minute 56 seconds, un-authenticated session
Configured BGP Maximum Prefix Limit 125
DampPeer Oscillations ENABLED
Configured Connect Retry Count 5
Current Connect Retry Count 0
Peer Passive : ENABLED
Peer Status : NOT DAMPED
Idlehold time is 60 Rcvd update before 0 secs, hold time is 90, keepalive interval is 35 secs
Neighbors Capability:
Route-Refresh: Advertised and received
Address family IPv4 Unicast: Advertised and received
Received 5 messages, 0 Updates
Sent 5 messages, 0 Updates
Route refresh: Received 0, sent 0.
Minimum time between advertisement runs is 15 seconds
Connections established 2 time(s)
Local host: 14.0.0.2, Local port: 179
Foreign host: 14.0.0.1, Foreign port: 49153
Last Error: Code 0, SubCode 0.
BGP neighbor is 15.0.0.2, remote AS 100, internal link
BGP version 4, remote router ID 15.0.0.2
BGP state = Established, up for 1 minute 56 seconds, un-authenticated session
Configured BGP Maximum Prefix Limit 125
DampPeer Oscillations ENABLED
Configured Connect Retry Count 5
Current Connect Retry Count 0
Peer Passive : ENABLED
Peer Status : NOT DAMPED
Idlehold time is 60 Rcvd update before 0 secs, hold time is 90, keepalive interval is 35 secs
Neighbors Capability:
Route-Refresh: Advertised and received
Address family IPv4 Unicast: Advertised and received
Received 5 messages, 0 Updates
Sent 5 messages, 0 Updates
Route refresh: Received 0, sent 0.
Minimum time between advertisement runs is 15 seconds
Connections established 2 time(s)
Local host: 15.0.0.1, Local port: 179
Foreign host: 15.0.0.2, Foreign port: 49153
Last Error: Code 0, SubCode 0.
BGP neighbor is 16.0.0.2, remote AS 100, internal link
BGP version 4, remote router ID 16.0.0.2
BGP state = Established, up for 1 minute 26 seconds, un-authenticated session
Configured BGP Maximum Prefix Limit 125
DampPeer Oscillations ENABLED
Configured Connect Retry Count 5
Current Connect Retry Count 0
Peer Passive : ENABLED
Peer Status : NOT DAMPED
Idlehold time is 60 Rcvd update before 0 secs, hold time is 90, keepalive interval is 35 secs
Neighbors Capability:
Route-Refresh: Advertised and received
Address family IPv4 Unicast: Advertised and received
Received 4 messages, 0 Updates
Sent 4 messages, 0 Updates
Route refresh: Received 0, sent 0.
Minimum time between advertisement runs is 15 seconds
Connections established 2 time(s)
Local host: 16.0.0.1, Local port: 179
Foreign host: 16.0.0.2, Foreign port: 49152
Last Error: Code 0, SubCode 0.