BGP issue on cisco 1905

[manoj.kumar0074]

Hello All,

I am facing some issue on BGP.I configured BGP on cisco 1905 but . BGP neighborship is not forming.

I am attaching my Show tech and BGP debug.Please help me to out on this.

[Mahesh Gohil]

Hello Manoj,

I have seen log in debug output

*Nov 18 12:38:28.527: %BGP-3-NOTIFICATION: received from neighbor 194.168.4.149 passive 2/7 (unsupported/disjoint capability) 6 bytes 41040000 FC00
*Nov 18 12:38:31.991: BGP: nbr_topo global 194.168.4.149 IPv4 Unicast:base (0x2726E074:0) Not scheduling for GR processing [Peer did not advertise GR cap]
*Nov 18 12:38:31.991: BGP: ses global 194.168.4.149 (0x2726E074:0) act Reset (Peer closed the session).

Which tells that peer is not having capability for graceful-restart. You can disable this feature with global bgp command "no bgp graceful-restart"

But make sure you do not have any other peer need this feature.

Or

You can give one hidden command "dont-capability-negotiate" per neighbor i.e neighbor 194.168.4.149 dont-capability-negotiate

Hope this helps

Regards

Mahesh

[sfaizul]

Hi Manoj,

This error message basically indicates that the two BGP neighbors didn't
agree on some of
the capabilities configured under the BGP configuration. This is as per RFC
2842 for
Capabilities Advertisement with BGP-4. I am pasting the paragraph below,
that explains
this:

"If a BGP speaker that supports a certain capability determines that
   its peer doesn't support this capability, the speaker may send a
   NOTIFICATION message to the peer, and terminate peering. The Error
   Subcode in the message is set to Unsupported Capability. The message
   should contain the capability (capabilities) that causes the speaker
   to send the message.  The decision to send the message and terminate
   peering is local to the speaker.  Such peering should not be re-
   established automatically."

-
http://www.faqs.org/rfcs/rfc2842.html


Because the new code you are running supports capabilities that your other
peers do not please add the following command on the router to the peer
that is not coming up

neighbor x.x.x.x dont-capability-negotiate

If you are using prefix lists for your peer you can use this command as well

no neighbor x.x.x.x capabilities orf prefix-list both

Hope it will help.

Regards

Syed.

[manoj.kumar0074]

Dear Syed,

Thanks for your suggestion its really helpful.I applied these command and now BGP session established.

[ปลาวาฬทราย RMUTT CPE IX]

I found log:

Apr 12 09:35:27 THA: %BGP-3-NOTIFICATION: sent to neighbor [IPv6] 2/7 (unsupported/disjoint capability) 0 bytes  FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 0035 0104 122B 00B4 CA2F FD25 1802 0601 0400 0200 0102 0280 0002 0202 0002 0641 0400 0012 2B

I use this can solved:

router bgp [ASN]
address-family ipv6
neighbor [IPv6] activate