Determine difference between 2 BGP feeds
Bill Nash
billn at odyssey.billn.net
Tue Apr 18 22:08:41 UTC 2006
On Tue, 18 Apr 2006, David Andersen wrote:
> Much of what Bill described below is already present using Nick Feamster's
> bgptools release: http://nms.lcs.mit.edu/software/bgp/bgptools/
>
> Start with zebra / quagga / etc., which do a great job of dumping tables and
> updates.
>
> Then use bgptools to take the MRT-formatted dumps that Zebra spits out and
> turn them into text, etc. With the '-q' option, can insert the BGP updates
> or table snapshot directly into a SQL database.
My peer actually comes from a Zebra box, so I'm not talking directly to
any production devices, in the event that I want to bounce my db feed up
and down (debugging, featuritis treatments, etc) Z/Q + bgptools is a great
suggestion for doing complex reporting/comparison on the routing tables,
though. I've got a need for a more real-time view, so my setup fits me a
little better than your suggestion, but potato/potatoe. =)
> then the libbgpdump.a library gives you lots of cool things on top of that.
> You'd have to do a little work to get the analysis tool you want, but it's
> pretty easy. Use the 'buildtree' starting program to build the prefix tree
> from each provider and then compare those two trees (see which prefixes are
> present/not present, see if any parts of the IP space are unreachable in in
> one and unreachable in the other, etc.)
This is pretty interesting, I'll have to tinker with it, especially since
I know one of my providers doesn't give me a full routing table.
> It starts as Bill suggested - a read-only BGP peer from the devices, which
> takes about 3 seconds to set up.
And for folks to whom this is new stuff: don't be an idiot, put
Zebra/Quagga up as a peer/buffer for attaching analysis tools to your
network. *Never* attach development grade tools to a production device,
most especially when you're dealing with a routing table. Not that I've
ever taken down a live router in this manner[1], I'm just saying.. ;)
- billn
[1] All smirking current/past coworkers are kindly invited to stfu. =)
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