How to configure BGP Peer Group

Written on by admin on. Posted in BGP

BGP peer groups are used to simplify configuration and to improve performance. It can be used when a router has a group of neighbors with the same update policies. The update is generated once per group rather than for each neighbor.

To create and use a peer group follow next steps:

  •  type neighbor group-name peer-group to create a peer-group, where group-name is the name that you give to the peer group.
  • next, enter neighbor ip-address peer-group group-name command, which will make a neighbor to be part of peer group.
You can reset connections to member of a group by typing clear ip bgp peer-group group-name command in exec mode.

Now, let’s proceed to configuration. Below you have the scenario that will be used.

BGP-peer-group I will show how to configure BGP peer group on BORDER router in AS 64520 from picture above. Loopback ip addresses are used as source of BGP packets. Let’s assume we have connection from BORDER router to all devices in AS 64520. If to not use BGP peer group, configuration on BORDER router with the others will look like this: 
router bgp 64520
 neighbor 10.0.0.2 remote-as 64520
 neighbor 10.0.0.2 update-source loopback 0
 neighbor 10.0.0.2 next-hop-self  
 neighbor 10.0.0.3 remote-as 64520
 neighbor 10.0.0.3 update-source loopback 0
 neighbor 10.0.0.3 next-hop-self
 neighbor 10.0.0.4 remote-as 64520
 neighbor 10.0.0.4 update-source loopback 0
 neighbor 10.0.0.4 next-hop-self

With this configuration BGP updates will be generated for each neighbor, but if use peer group, updates are generated once per peer-group. If to use BGP peer-group, configuration on BORDER router will look like this:

router bgp 64520
 neighbor local peer-group
 neighbor local remote-as 64520
 neighbor local update-source loopback 0
 neighbor local next-hop-self
 neighbor 10.0.0.2 peer-group local
 neighbor 10.0.0.3 peer-group local
 neighbor 10.0.0.4 peer-group local

The name of BGP peer-group is local, this you can see from configuration above, also we get a more robust configuration.

That’s all for now, I wish all the best to you!

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Comments (12)

  • Ste

    |

    you said above: neighbor ip-address peer-group group-name

    so, if the group-name is “local”, why dont we have:

    neighbor 10.0.0.2 peer-group local?

    Reply

    • admin

      |

      Sorry for the mistake, yes, it must be “neighbor 10.0.0.2 peer-group local” as you said. I have corrected it.

      Reply

  • CiscoStud

    |

    Very good and helpful! Thank you 🙂

    Reply

  • jay

    |

    Humble thanx for such a short and precised note on peer group.

    Want to know regarding the outbound policy which are supposed to be same for all the routers in the group. In what means they are supposed to be same . They may have different connections to different networks. Can u plz through some light.

    Reply

    • admin

      |

      Hi Jay, The meaning of “the same update policies” is that from a router perspective update policies related to a group of neighbors are the same, like “update source”,”next hop self” and so on.

      Reply

  • gurmeet

    |

    Nice!!!

    Reply

  • CCIE Dra

    |

    Veryyyy Wellllllllllll

    Reply

  • Ratha

    |

    do we need IGP in AS 64520? if need, why?

    thank for your support!

    Reply

    • admin

      |

      Hi Ratha,

      All the routers inside AS 64520 that need to establish iBGP sessions, need to be reachable with each other. So, to achieve this you need an IGP, if not a dynamic IGP, at least static routes to each other.

      BR

      Reply

  • Amjad

    |

    Thank you.

    Reply

  • D.P

    |

    In updates or policies sending direction in current peer group will be as below,
    out-bound Update or policies from Border router to all neighbor will send to group. But in-bound updates or policies from each neighbor to Border router will send directly to Border router instead of sending to group.

    Reply

  • Mukesh Gupta

    |

    ROUTER1
    router bgp 1
    no synchronization
    bgp log-neighbor-changes
    neighbor LOCAL peer-group
    neighbor LOCAL remote-as 1
    neighbor LOCAL update-source Loopback3
    neighbor 192.168.23.1 peer-group LOCAL
    no auto-summary

    ROuter2-
    router bgp 1
    no synchronization
    bgp log-neighbor-changes
    neighbor LOCAL peer-group
    neighbor LOCAL remote-as 1
    neighbor LOCAL update-source Loopback2
    neighbor LOCAL next-hop-self
    neighbor 192.168.23.2 peer-group LOCAL
    no auto-summary

    Router#show ip bgp summary
    BGP router identifier 2.2.2.2, local AS number 1
    BGP table version is 1, main routing table version 1

    Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
    192.168.23.2 4 1 0 0 0 0 0 never Active
    Router#

    plz help

    Reply

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