Routing problems after multiple peering

[Daniel Roesen]

On Sun, Mar 06, 2011 at 07:06:02PM +0100, Olivier MJ Crepin-Leblond wrote:
> We're connected to a router on AS31493. Details of our feed's peering
> arrangements on: http://bgp.he.net/AS31493

I guess NewNet AS9191 is the upstream they added recently?

What route(s) do you advertise to AS31493 really?

> When tracerouting (from outside) to two machines on our same subnet, one
> works whilst the other one doesn't.

That's broken. The looping inside(?) AS9191 (NewNet) is a pretty good
indication that something's broken there, UNLESS the :200 hop is
actually AS31493's end of of a link (thus different administrative
domain).

I'd guesstimate ECMP at work at NewNet, with one path being somewhat
broken.

But definatetly not enough information provided to know for sure....

> Please be so kind to advise how to fix this. Looks like route flapping,
> or something else?

I'd have your upstream contact their upstream NewNet...

Best regards,
Daniel

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