We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is Why:

  • Learn any CCNA, CCNP and CCIE R&S Topic. Explained As Simple As Possible.
  • Try for Just $1. The Best Dollar You've Ever Spent on Your Cisco Career!
  • Full Access to our 588 Lessons. More Lessons Added Every Week!
  • Content created by Rene Molenaar (CCIE #41726)


314 New Members signed up the last 30 days!


100% Satisfaction Guaranteed!
You may cancel your monthly membership at any time.
No Questions Asked!

Forum Replies

  1. Great explanation. Peer groups saves a lot of time and headache. Thanks

    CCIE R&S - in progress

  2. Hi Rene,

    I think that in configuration there is missing a static route to each of the peer's loopback addresses.


  3. Hi Aswin,

    The functionality remains the same but behind the scenes, something is different. Imagine you have 100 BGP neighbors...they all have the same configuration. Without peer groups, the router will have to generate an update for each neighbor, one-by-one.

    With peer groups, the update is generated only once for the peer group. For each neighbor, we only have to replicate the update..that's it. That saves some CPU cycles on the router.

    I have to say that most routers also support BGP Dynamic Update Peer-Groups. This means that routers will automatically try to replicate packets "behind the scenes" for each neighbor, even when you are not using peer groups. Peer groups are still useful since they simplify your configuration.


  4. Hi,

    I have a problem in R1 he doesn't create any neighbor relationship:

    These are the logs:

    *Jul  9 17:58:35.187: BGP: ses global (0x655EF9CC:0) act Reset (Active open failed).
    *Jul  9 17:58:35.199: BGP: active went from Active to Idle
    *Jul  9 17:58:35.199: BGP: nbr global Active open failed - open timer running
    *Jul  9 17:58:35.203: BGP: nbr global Active open failed - open timer running

    Example for R3 but it's the same for R2 and R4:

    router bgp 1
     bgp log-neighbor-changes
     neighbor R2_R3_R4 peer-group
     neighbor R2_R3_R4 ebgp-multihop 2
     neighbor R2_R3_R4 update-source Loopback0
     neighbor remote-as 2
     neighbor peer-group R2_R3_R4
     neighbor remote-as 3
     neighbor peer-group R2_R3_R4
     neighbor remote-as 4
     neighbor peer-group R2_R3_R4
  5. Hi Adiel,

    These two lessons might help to understand what is going on:

    BGP Neighbor Adjacency States

    Troubleshooting BGP Neighbor Adjacency

    Is your router able to reach, or Are R2, R3 and R4 able to reach That's something to check. Make sure the BGP configuration on R2, R3 and R4 is also using the loopback address as the source of the connection and that multihop is configured.


2 more replies! Ask a question or join the discussion by visiting our Community Forum