Finding asymmetric path

Brielle Bruns bruns at
Sat Nov 28 21:02:23 UTC 2009

(Forgive the top posting, stupid blackberry can't do inline)

If the PoP is connected to a central location, reroute the affected netblock there through the appropriate equipment.  If you snag it going both ways before it hits the PoP, you should be good.

------Original Message------
From: Duane Waddle
To: nanog at
Subject: Re: Finding asymmetric path
Sent: Nov 28, 2009 1:26 PM

On Sat, Nov 28, 2009 at 1:41 PM, Brielle Bruns <bruns at> wrote:

> My partner Tammy says a PIX could probably accomplish the same task (we have some here for the corp lan stuff, including spares).

Yes, a PIX/ASA would stop this cold.  The TCP state tracking would not
allow traffic to pass unless the whole 3-way handshake was observed by
the box.  Only recently did Cisco add features to make tracking the
TCP connection state optional.
 The larger ASA-5580 machines can be virtualized into dozens (or more)
security contexts as needed.  I imagine it would take some effort to
figure out how to cleanly integrate such a configuration into a POP.


Brielle Bruns  /

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