BGP Session Teardown due to AS_CONFED_SEQUENCE in AS4_PATH

Rob Shakir rjs at
Tue Jan 20 10:35:48 UTC 2009

On Mon, Jan 19, 2009 at 03:58:17PM +0000, Jonathan Oddy wrote:
> As mentioned in both [1] and [2] this is especially critical as at
> present Cisco IOS will tear down sessions when receiving an AS4_PATH
> containing an AS_CONFED_SET/SEQUENCE.


Whilst this is behaviour is RFC compliant, as previously described, it is
sub-optimal operationally. I have raised this issue with Cisco TAC, and
CSCsx10140 has been opened to track this problem.

I would encourage those network operators who may be planning to deploy
AS4-support and use Cisco equipment to open a SR with Cisco, tracking this bug,
to try to ensure that both the IOS behaviour, and RFC are changed.

Many thanks,

Rob Shakir                      <rjs at>
Network Development Engineer    GX Networks/Vialtus Solutions
ddi: +44208 587 6077            mob: +44797 155 4098
pgp: 0xc07e6deb                 nic-hdl: RJS-RIPE

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