bgp update destroying transit on redback routers ?

[morrowc.lists at gmail.com (Christopher Morrow)]

On Fri, Dec 2, 2011 at 9:35 AM, Alexandre Snarskii <snar at snar.spb.ru> wrote:

> This draft says that

...note it's a DRAFT, not a STANDARD...

>
> If a BGP speaker receives a route which has an AS number of zero in the
> AS_PATH (or AS4_PATH) attribute, it SHOULD be logged and treated as a
> WITHDRAW. This same behavior applies to routes containing zero as the
> Aggregator or AS4 Aggregator.
>
> but observed behaviour was more like following:
>
> If a BGP speaker receives [bad route] it MUST close session immediately
> with NOTIFICATION Error Code 'Update Message Error' and subcode 'Error with
> optional attribute'.

hence this old behavor