Asymmetric traffic/topology

Greetings.

I am sure that most of you know about the asymmetric traffic/topology
problem in relevance to
IDS/IPS systems.
( By Asymmetric traffic/topology, I mean the case where client to
server packets traverse a different path
in your network compared to server to client packets. Hence the
IDS/IPS see only one side of the conversation)

I am trying to find out how wide this problem really is?
Is it commonly seen in large / enterprise networks ?

Any input is welcome.

Thanks

------------------------------------------------------------------------
Test Your IDS

Is your IDS deployed correctly?
Find out quickly and easily by testing it 
with real-world attacks from CORE IMPACT.
Go to 
http://www.coresecurity.com/index.php5?module=Form&action=impact&campaign=intro_sfw
 
to learn more.
------------------------------------------------------------------------