[j-nsp] Error BGP RECV Notification code 2 (Open Message Error) subcode 7 (unsupported capability)

[khagendra dhakal]

Dear all,

Platform: M10i
JUNOS: JUNOS 9.2R2.15

Platform: Maipu 2800
IOS: rp8-i-6.1.37(xnwt-11).bin), version 6.1.37


PROBLEM: Has anyone had any bad experience on bgp peering between the
above mentioned Devices with the following error: ?

Error:
BGP RECV xxx.xxx.xxx.xxx+3407 -> xxx.xxx.xxx.xxx+179
BGP RECV message type 3 (Notification) length 27
BGP RECV Notification code 2 (Open Message Error) subcode 7
(unsupported capability)
BGP RECV Data (6 bytes): 41 04 00 00 b3 15
bgp_peer_close: closing peer xxx.xxx.xxx.xxx (External AS xxxxx),
state is 5 (OpenConfirm)
bgp_close_socket: peer xxx.xxx.xxx.xxx (External AS xxxxx)
...........................
............................
advertising receiving-speaker only capabilty to neighbor
xxx.xxx.xxx.xxx (External AS xxxxx)
bgp_4byte_aspath_add_cap():153 AS4-Peer xxx.xxx.xxx.xxx (External AS
xxxxx)(SEND): 4 byte AS capability added, AS xxxxx

Please suggest the appropriate solution to get out of this issue.

Regards,
Khagendra Dhakal
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[Chuck Anderson]

set neighbor w.x.y.z disable-4byte-as

On Thu, May 20, 2010 at 09:03:55PM +0545, khagendra dhakal wrote:
> Dear all,
>
> Platform: M10i
> JUNOS: JUNOS 9.2R2.15
>
> Platform: Maipu 2800
> IOS: rp8-i-6.1.37(xnwt-11).bin), version 6.1.37
>
>
> PROBLEM: Has anyone had any bad experience on bgp peering between the
> above mentioned Devices with the following error: ?
>
> Error:
> BGP RECV xxx.xxx.xxx.xxx+3407 -> xxx.xxx.xxx.xxx+179
> BGP RECV message type 3 (Notification) length 27
> BGP RECV Notification code 2 (Open Message Error) subcode 7
> (unsupported capability)
> BGP RECV Data (6 bytes): 41 04 00 00 b3 15
> bgp_peer_close: closing peer xxx.xxx.xxx.xxx (External AS xxxxx),
> state is 5 (OpenConfirm)
> bgp_close_socket: peer xxx.xxx.xxx.xxx (External AS xxxxx)
> ...........................
> ............................
> advertising receiving-speaker only capabilty to neighbor
> xxx.xxx.xxx.xxx (External AS xxxxx)
> bgp_4byte_aspath_add_cap():153 AS4-Peer xxx.xxx.xxx.xxx (External AS
> xxxxx)(SEND): 4 byte AS capability added, AS xxxxx
>
> Please suggest the appropriate solution to get out of this issue.

[khagendra dhakal]

Hi Chuck,

I applied the command (hidden/ undocumented) and it worked.

M10i already has many peers that support *2 byte asn only* and is running
without any issues, but *why it is not able to negotiate with Maipu to make
the peer up without disabling the 4byte asn capability*.

ASFAIK, 4 byte ASN or AS4_PATH is an optional transitive attribute unlike
AS_PATH mandatory attribute. My asmuntion is BGP new_speaker may send
AS4_PATH to its neighbor an OPEN message with capability check, if fail it
should have to use AS_PATH or 2 byte to negotiate to its OLD-BGP speakers
and make the peer up.

*The question is why JunOs failed with Maipu ?
*
Thank you,
Khagendra Dhakal

[sth...@nethelp.no]

> M10i already has many peers that support *2 byte asn only* and is running
> without any issues, but *why it is not able to negotiate with Maipu to make
> the peer up without disabling the 4byte asn capability*.
>
> ASFAIK, 4 byte ASN or AS4_PATH is an optional transitive attribute unlike
> AS_PATH mandatory attribute. My asmuntion is BGP new_speaker may send
> AS4_PATH to its neighbor an OPEN message with capability check, if fail it
> should have to use AS_PATH or 2 byte to negotiate to its OLD-BGP speakers
> and make the peer up.
>
> *The question is why JunOs failed with Maipu ?

No, the correct question is, why did Maipu fail?

JunOS announces 4 byte ASN capability in all reasonably new versions.
Some peers cannot handle this, Maipu seems to be among them.

We have had to disable the 4 byte ASN capability announcement towards
a few customers having BGP speaking firewalls and similar stuff.

Steinar Haug, Nethelp consulting, sth...@nethelp.no