BGP Route Issues
chris.karel at gmail.com
Mon Aug 19 01:33:39 UTC 2013
I'm hoping you guys might be able to offer some advice or insight
into a BGP problem I've got. I've noticed some strange routes between
our network, AS27270, and AS22943. It looks like both our networks are
dual homed. One ISP as the primary, and the other used as a backup,
with path prepending to prevent it from actually being used except in an
outage. However, our route to 22943 appears to be using their backup
link. (27270 4323 7018 22943 22943 22943 22943 22943 22943 22943 22943
22943 22943 22943) Which is strange, because we can reach their primary
ISP without any such rigmarole.
Playing around with Looking Glass servers indicates that Cogent
(AS174) has a similar backup route to our network. (174 22402 27270
27270 27270 27270 27270 27270) Everywhere else I check seems perfectly
sane. But since Cogent is essentially in-between the two networks I'm
troubleshooting, I would assume that the other network has a similar
route. But Cogent won't talk with me about this, since I'm not a customer.
So as far as advice goes, is there a common issue that might result
in such poor routes in both directions? Any further troubleshooting
that I should be doing? Or any ideas on how to help remedy things that
appear to be outside our network/ISP? Or are we doing something so
wrong that this is all my fault?
I'd really appreciate any input on this.
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