nanog mailing list archives

Re: Re: Private ASNs in the wild


From: Mark Tinka <mark.tinka () seacom mu>
Date: Fri, 23 Jan 2015 19:50:50 +0200

On Thursday, December 11, 2014 05:55:26 PM ML wrote:

There are sloppy networks out there.  If it was a big
enough problem all you'd need is a few key networks drop
those prefixes and we'd have a...slightly less sloppy
Internet?

Router software (speaking of Cisco and Juniper in this case) has developed 
reasonably well that one can now strip private ASN's from the AS_PATH 
even though they now appear in between public ASN's.

This was not possible before, as private AS filtering was only possible if 
they appeared contiguously in the AS_PATH.

Of course, this means running later code - but chances are that if you're 
running code that supports 4-byte ASN's, you might have this feature.

Not sure about other vendors out there.

We, for example, remove private ASN's by default on all eBGP sessions. I 
know several other providers that do the same - but it takes a village to 
raise the Internet...

Mark.

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