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Thread: Determine difference between 2 BGP feeds




Determine difference between 2 BGP feeds
user name
2006-04-18 22:08:41

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. =)
[1]

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