BGP issues

Wed Sep 17 21:29:31 UTC 2003

Bret Baptist wrote:
[...]
> Right now I have visi.com as one provider (AS8015), and Qwest (AS3908) as the
> other.  When I look at the as-paths for my netblocks the ones from visi.com
> look fine, 208.42.20.0/23 and 208.42.104.0/23, the ones from Qwest go through
> visi.com and then on to us, 65.116.186.0/24, 65.121.8.0/23.  The Qwest
> networks are the ones that I am having problems reaching hosts from or
> getting to from other networks. [...]

  It's a bit of a long shot and difficult to see, but when I see natural
C blocks without problems and natural A blocks with, I tend to suspect
class-based filtering.  This usually occurs if there's no less-specific
route available, but there's 65.112.0.0/12 from Qwest covering both. 
This leaves only a few very obscure possibilities, so I wouldn't chase
this except as a last resort.

Peter E. Fry