[147798] in North American Network Operators' Group
RE: bgp update destroying transit on redback routers ?
daemon@ATHENA.MIT.EDU (Jeff Tantsura)
Thu Dec 22 13:43:17 2011
From: Jeff Tantsura <jeff.tantsura@ericsson.com>
To: Olivier Benghozi <olivier.benghozi@wifirst.fr>, "nanog@nanog.org"
<nanog@nanog.org>
Date: Thu, 22 Dec 2011 13:42:15 -0500
In-Reply-To: <87CD9A36-6A74-465C-8154-7C9F58640773@wifirst.fr>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Olivier,
Thanks!
We've done our best to provide the fix ASAP.
Regards,
Jeff
-----Original Message-----
From: Olivier Benghozi [mailto:olivier.benghozi@wifirst.fr]=20
Sent: Thursday, December 22, 2011 5:20 AM
To: nanog@nanog.org
Cc: Alexandre Snarskii; Jeff Tantsura
Subject: Re: bgp update destroying transit on redback routers ?
Aha, it looks that our Quebecer friends from Hostlogistic (AS46609) have ag=
ain been advertising their now famous funny aggregate with their mad Brocad=
e 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 se=
ssions.
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=20
> NOTIFICATION message, with the indicated Error Code, Error Subcode, and D=
ata 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=20
> draft-chen-ebgp-error-handling, however please note - this is still a dra=
ft, not a normative document and with all my support it takes time to imple=
ment.
>=20
> Once again, we understand the implications for our customers and hence go=
ing to disable ASN 0 check.
>=20
> P.S. We have strong evidence that the update in question was caused by=20
> a bug on a freshly updated router (I'm not going to disclose the=20
> vendor)
>=20
> Regards,
> Jeff
>=20
>=20
> -----Original Message-----
> From: Alexandre Snarskii [mailto:snar@snar.spb.ru]
> 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
>> (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 A=
S_PATH (or AS4_PATH) attribute, it SHOULD be logged and treated as a WITHDR=
AW. 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 w=
ith NOTIFICATION Error Code 'Update Message Error' and subcode 'Error with =
optional attribute'.
