[147793] in North American Network Operators' Group
Re: bgp update destroying transit on redback routers ?
daemon@ATHENA.MIT.EDU (Olivier Benghozi)
Thu Dec 22 08:21:27 2011
From: Olivier Benghozi <olivier.benghozi@wifirst.fr>
In-Reply-To: <0ED867EB33AB2B45AAB470D5A64CDBF6181C2EDEB6@EUSAACMS0701.eamcs.ericsson.se>
Date: Thu, 22 Dec 2011 14:20:21 +0100
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Aha, it looks that our Quebecer friends from Hostlogistic (AS46609) have =
again been advertising their now famous funny aggregate with their mad =
Brocade router, since yesterday 10pm UTC (that is 5pm in Quebec)...
Same route to 206.125.164.0/22, same AGGREGATOR attribute full of 0.
At least I can say that the patched Ericsson's bgpd stopped reseting the =
sessions.
regards,
Olivier
Le 2 d=E9c. 2011 =E0 23:14, Jeff Tantsura a =E9crit :
> Hi Alexandre,
>=20
> You are right, the behavior is exactly as per RFC4271 section 6:
> "When any of the conditions described here are detected, a
> NOTIFICATION message, with the indicated Error Code, Error Subcode, =
and Data fields, is sent, and the BGP connection is closed.
> So because ASN 0 in AGGREGATOR is seen as a malformed UPDATE we send =
3/9 and close the connection.
>=20
> Ideally it should be treated as "treat-as-withdraw" as per =
draft-chen-ebgp-error-handling, however please note - this is still a =
draft,=20
> not a normative document and with all my support it takes time to =
implement.
>=20
> Once again, we understand the implications for our customers and hence =
going to disable ASN 0 check.
>=20
> P.S. We have strong evidence that the update in question was caused by =
a bug on a freshly updated router (I'm not going to disclose the vendor)=20=
>=20
> Regards,
> Jeff
>=20
>=20
> -----Original Message-----
> From: Alexandre Snarskii [mailto:snar@snar.spb.ru]=20
> Sent: Friday, December 02, 2011 6:36 AM
> To: Jeff Tantsura
> Cc: nanog@nanog.org
> Subject: Re: bgp update destroying transit on redback routers ?
>=20
> On Thu, Dec 01, 2011 at 04:56:43PM -0500, Jeff Tantsura wrote:
>> Hi,
>>=20
>> Let me take it over from now on, I'm the IP Routing/MPLS Product=20
>> Manager at Ericsson responsible for all routing protocols.
>> There's nothing wrong in checking ASN in AGGREGATOR, we don't really=20=
>> want see ASN 0 anywhere, that's how draft-wkumari-idr-as0=20
>> (draft-ietf-idr-as0-00) came into the worlds.
>=20
> This draft says that
>=20
> 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.
>=20
> but observed behaviour was more like following:=20
>=20
> 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'.
