BGP Route Issues

Fakrul Alam Pappu fakrulalam at gmail.com
Mon Aug 19 12:27:08 UTC 2013


Won't it be backslash rather than forward slash?

_([0-9]+) _\1_\1_\1_


On Mon, Aug 19, 2013 at 9:51 AM, Randy <randy_94108 at yahoo.com> wrote:

> 11 prepends is beyond-excessive besides being annoying.
> filter please _([0-9]+) _/1_/1_/1_
>
>
>
>
> >________________________________
> > From: Blake Dunlap <ikiris at gmail.com>
> >To: Christopher Karel <chris.karel at gmail.com>
> >Cc: "nanog at nanog.org" <nanog at nanog.org>
> >Sent: Sunday, August 18, 2013 7:42 PM
> >Subject: Re: BGP Route Issues
> >
> >
> >Local Pref (which is common by the way to be set so customers > peers >
> >transit). AS Path doesn't beat it.
> >You can only request people follow the routes you want ingress, there's
> >nothing you can do to force them to take a path to you short of
> >deaggregation, and that only works until they notice it, and it irratates
> >the rest of the world as well by using additional route slots.
> >
> >Poor routing is purely a viewpoint problem, not necessarily in agreement
> >between all parties.
> >
> >-Blake
> >
> >
> >On Sun, Aug 18, 2013 at 8:33 PM, Christopher Karel <chris.karel at gmail.com
> >wrote:
> >
> >>   Good evening,
> >>
> >>     I'm hoping you guys might be able to offer some advice or insight
> into
> >> a BGP problem I've got.  I've noticed some strange routes between our
> >> network, AS27270, and AS22943.  It looks like both our networks are dual
> >> homed.  One ISP as the primary, and the other used as a backup, with
> path
> >> prepending to prevent it from actually being used except in an outage.
> >>  However, our route to 22943 appears to be using their backup link.
> (27270
> >> 4323 7018 22943 22943 22943 22943 22943 22943 22943 22943 22943 22943
> >> 22943)  Which is strange, because we can reach their primary ISP without
> >> any such rigmarole.
> >>
> >>     Playing around with Looking Glass servers indicates that Cogent
> >> (AS174) has a similar backup route to our network.  (174 22402 27270
> 27270
> >> 27270 27270 27270 27270)  Everywhere else I check seems perfectly sane.
> >>  But since Cogent is essentially in-between the two networks I'm
> >> troubleshooting, I would assume that the other network has a similar
> route.
> >>  But Cogent won't talk with me about this, since I'm not a customer.
> >>
> >>     So as far as advice goes, is there a common issue that might result
> in
> >> such poor routes in both directions?  Any further troubleshooting that I
> >> should be doing?  Or any ideas on how to help remedy things that appear
> to
> >> be outside our network/ISP?  Or are we doing something so wrong that
> this
> >> is all my fault?
> >>
> >> I'd really appreciate any input on this.
> >>
> >>
> >
> >
> >
>


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