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Re: Same AS number from different location
On 24 May 2008, at 00:08, devang patel wrote:
Is that okay to use Same AS number for the two different site on different
From the perspective of the rest of the Internet, it will be indistinguishable from a topologically-distributed AS with interior connectivity, with a different exit policy in different places. So yes, it will work.
You should note, though, that in the presence of interior connectivity (e.g. a circuit directly between the sites) site A would learn routing information about site B internally, and it would not matter that site A doesn't hear BGP routes announced to the Internet from site B (in fact, that would be a feature). If you have no internal connectivity, you might have to think a little harder about that.
I have seen some people plumb tunnels between their sites to provide interior-looking connectivity where none actually exists.
I have seen other people not worry so much, and just point default at transit from each place.
as well as any good documentation or link or deployment scenario where I can
I seem to think you'll find presentations about AS consolidation in the NANOG meeting archives, somewhere. But basically you join your ASes together, start advertising routes from the to-remain AS and drop the corresponding routes from the going-away AS, with appropriate pauses for checks and breathing.
To renumber, change the addresses on individual things with appropriate pauses for DNS TTL expiry. Where changes require interaction with customers, good luck and be patient (or drive round and change the config on their routers yourself, or give up waiting and expect them to get back to you when their net stops working, as appropriate).