nanog mailing list archives

Re: Connectivity to Brazil


From: Valdis.Kletnieks () vt edu
Date: Tue, 01 Feb 2011 15:19:53 -0500

On Tue, 01 Feb 2011 08:54:47 EST, Steve Danelli said:

Some carrier, somewhere between us and the service provider is selectively
dropping the IKE packets originating from our VPN gateway and destined for
our Brazil gateway. Other traffic is able to pass, as are the IKE packets coming
back from Brazil to us. This is effectively preventing us from establishing
the IPSEC tunnel between our gateways.

Has IKE been known to work to that location before? Or is this something new?
My first guess is some chucklehead banana-eater at the service provider either
fat-fingered the firewall config, or semi-intentionally blocked it because it
was "traffic on a protocol/port number they didn't understand so it must be
evil".

Also something else is awry, for two given hosts on the same subnet (x.y.z.52
and x.y.z.53), they take two wildly divergent paths:

Anyone have any insight on to what may be occurring?

The paths appear to diverge at 67.16.142.238.  I wonder if that's gear trying
to do some load-balancing across 2 paths, and it's using the source IP as a
major part of the selector function ("route to round-robin interface source-IP
mod N" or similar?).

The other possibility is your two traceroutes happened to catch a routing flap in
progress (obviously not the case if the two routes are remaining stable).

Sorry I can't be more helpful than that...

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