Determine difference between 2 BGP feeds
Richard A Steenbergen
ras at e-gerbil.net
Tue Apr 18 20:56:05 UTC 2006
On Tue, Apr 18, 2006 at 04:28:40PM -0400, Scott Tuc Ellentuch at T-B-O-H wrote:
>
> >
> > On Tue, 18 Apr 2006, Scott Tuc Ellentuch at T-B-O-H wrote:
> >
> > > Is there a utility that I can use that will pull the
> > > routes off each router (Foundry preferred), and then compare
> > > them as best it can to see why there is such a difference?
> > > I can understand a handful of routes over what CIDR says,
> > > but a minimum of 3K more?
> >
> > Is one of them as4323?
> >
> Actually, no. I wasn't wanting to "name names" to
> protect the innocent... BUT....
>
> ROUTER1:
> Neighbor Address AS# State Time Rt:Accepted Filtered Sent ToSend
> 64.200.58.69 7911 ESTAB 4d21h57m 182287 0 4 0
>
> ROUTER2:
> Neighbor Address AS# State Time Rt:Accepted Filtered Sent ToSend
> 69.28.152.229 22822 ESTAB 18d16h51m 186379 0 4 0
This is actually fairly common. There are a lot of folks out there who
announce more specifics to one network but not another, or who apply no
export or limited export community tags in various places. Also, every
network has a different filter policy of what they will and won't accept.
FWIW my "exported to bgp speaking customers" count at this moment is
182525. I wouldn't get concerned about it unless the network with more
prefixes is doing something absurdly stupid like sending you internal /30s
and such (which, well, a lot of people do :P). It could also be something
like peers agreeing to traffic engineer by sending each other more
specifics w/meds, though if they were smart they would be doing that with
no-export so as to not make your TE job more difficult. If you really want
to compare the differences, try something like:
telnet yourrouter | tee outputfile
term length 0
sh ip bgp nei x.x.x.x received-routes
quit
Followed by 30 secs with awk(1), cut(1), diff(1), etc. For floundry,
something dirt simple like "grep / | awk '{ print $2 }'" should do the
trick.
--
Richard A Steenbergen <ras at e-gerbil.net> http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)
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