BGP Peering

Greetings all,

we have the below case,

R6--------> BB3

connected as EBGP. R6 in AS100 and BB3 in AS254. BB3 is configured to peer with R6 as R6 in AS3. Dont use confederation for this case.

R6

----

router bgp 100

neighbor 204.12.1.254 remote-as 254

neighbor 204.12.1.254 local-as 3

neighbor 204.12.1.254 ebgp-multihop

 

but the connection didnt came up - Established. what could be the issue?

 

regards

Jorf

Comments

  • R6# deb ip bgp out

     

  • Check the L2 conectivity, or the config on bb3

  • L2 connectivity is fine. how you gonna access BB router if you have such a Q in the lab?

  • Hi Bam,

    the command " deb ip bgp out" will it show what is the issue in BB router config?? will it give you a clear indication of the issue?

    "debug ip bgp" will show connection refused by remote host,delayed jitter......"

    regards

    Jorf

     

  • Is this from a specific workbook/lab?  Are you sure you don't have the AS3 / AS100 reversed?

  • Also verify that BB3 is in fact in AS254 [:D]

  • If it's refused then there's a mismatch with the AS or you need a password.

  • I usually do "debug ip tcp trans" first to see if the tcp handshake is completing.  If you see that the connection is being RST'd by either router you know that router is not expecting that particular connection.  Either the AS is wrong or the source address is wrong. 

  • izack's technique sounds pretty good. This is what's recommended in Cisco's BGP Case Study...

    Although, there's no mention of passwords matching, from experience it's one of the things not listed that will also cause the peers not to Establish.

  • <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">






    BGP Passwords are an MD5 hash.  That means both sides
    need to come up with the same value in order to match things. 
    :)

     

    Scott





    From: [email protected] [mailto:[email protected]]
    On Behalf Of bam
    Sent: Wednesday, December 24, 2008 3:07
    PM
    To: [email protected]
    Subject: Re: [CCIE
    R&S] BGP Peering


    izack's technique sounds pretty good. This is what's recommended in Cisco's
    BGP
    Case Study
    ...

    Although, there's no mention of passwords matching, from experience it's one
    of the things not listed that will also cause the peers not to Establish.




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  • Could this have been caused by incorrect update source? have you tried the BGP connection to the BB router after specifiying a different source interface (possibly a loopback you may have?)

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