[c-nsp] 3/11 (invalid or corrupt AS path)

[M Usman Ashraf]

Hi List,

Read this useful blog entry,

*http://www.renesys.com/blog/2009/02/the-flap-heard-around-the-worl.shtml*

It does not present a solution, but explains the cause in detail.

-- 
Regards,

M Usman Ashraf

On Wed, Feb 18, 2009 at 1:15 AM, Rodney Dunn <rodunn at cisco.com> wrote:

> Here is my update to NANOG...
>
> I'll post again once I have a further update.
>
>
> Date: Tue, 17 Feb 2009 15:11:57 -0500
> From: Rodney Dunn <rodunn at cisco.com>
> To: Ivan Pepelnjak <ip at ioshints.info>
> Subject: Re: anyone else seeing very long AS paths?
> Cc: nanog at nanog.org
>
> Ivan,
>
> It is confusing but from what I have tested you have it correct.
>
> The confusing part comes from multiple issues.
>
> a) The documentation about the default maxas limit being 75 appears to be
>   incorrect. I'll get that fixed.
>
> b) Prior to CSCee30718 there was a hard limit of 255. After that fix
>   AS sets of more than 255 should work.
>
> c) CSCeh13489 implemented the maxas command to mark it as invalid and
>   not send.
>
>
> There does appear to be an issue when you cross the 255 boundary
> and the next hop router sends a notification back.
>
> I've got it recreated in the lab and we are working to clearly understand
> why that is. I'll post an update once we have more.
>
> The way to prevent it is the upstream device that crosses the 255 boundary
> on sending needs to use the maxas limit command to keep it less than 255.
>
> It doesn't work on the device that receives the update with the AS path
> larger than 255.
>
> Rodney
>
>
> -=-
>
>
>
> On Mon, Feb 16, 2009 at 03:32:11PM -0500, Rodney Dunn wrote:
> > We are working on that. I'll let you know once I have more.
> >
> > Rodney
> >
> > On Tue, Feb 17, 2009 at 12:41:34AM +0500, M Usman Ashraf wrote:
> > > Hi List,
> > >
> > > We have just experience the same problem on SRC but with a different
> reason,
> > >
> > > %BGP-3-NOTIFICATION: sent to neighbor X.X.X.X 3/11 (invalid or corrupt
> AS path)
> > > 518 bytes 50020202 02009531 23012306 71B9BAFC BA
> > >
> > > 23w4d: BGP: X.X.X.X Bad attributes
> > >
> > > Feb 16 21:26:04.918 pst: %BGP-4-MSGDUMP: unsupported or mal-formatted
> message
> > > received from X.X.X.X:
> > > FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 022C 0200 0002 1140 0101 0050
> 0202 0202
> > > 0095 3123 0123 0671 B9BA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA FCBA
> > > FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA FCBA
> > > FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA FCBA
> > > FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA FCBA
> > > FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA FCBA
> > > FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA FCBA
> FCBA
> > > FCBA--
> > >
> > > Any idea of reason? or what can be a bad message for BGP that can tear
> down
> > > adjacency ?
> > >
> > > Regards,
> > >
> > > M Usman Ashraf
> > >
> > >
> > >
> > > On Tue, Feb 17, 2009 at 12:07 AM, Rodney Dunn <rodunn at cisco.com>
> wrote:
> > >
> > >     That would have to be *real* old code.
> > >
> > >     That was fixed back in the 12.1(4)
> > >
> > >     and 12.0(10)S3 days.
> > >
> > >     On Mon, Feb 16, 2009 at 01:25:32PM -0500, Tim Donahue wrote:
> > >     > Joe Provo wrote:
> > >     > > On Mon, Feb 16, 2009 at 06:14:08PM +0100, Grzegorz Janoszka
> wrote:
> > >     > >> Ozar wrote:
> > >     > >>> I am starting to see random BGP neighbor messages from
> multiple
> > >     neighbors
> > >     > >>> on
> > >     > >>> different boxes.
> > >     > >>>
> > >     > >>> %BGP-3-NOTIFICATION: received from neighbor X.X.X.X 3/11
> (invalid or
> > >     > >>> corrupt
> > >     > >>> AS path) 516 bytes
> > >     > > [snip]
> > >     > >> No, it is not software error, it is extremly long as-path:
> > >     > >
> > >     > > The message itself, correct.  The flapping sessions observed on
> some
> > >     > > code, the long path is indeed triggering some bug. It is
> immaterial
> > >     > > if it is the revival of an ld bug or a new one, there are folks
> > >     > > flapping over this (and related) paths.  Providers without some
> level
> > >     > > of sanity filters (really need many-multiples the current
> diameter of
> > >     > > the net?) should be shamed into limiting their customer's
> prepends.
> > >     > >
> > >     >
> > >     > According to the NANOG thread on this, it would seem that the bug
> would
> > >     > be CSCdr54230.
> > >     >
> > >     > Tim
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