nanog mailing list archives

Re: asymmetric routes/security concerns/Fortinet


From: "Justin M. Streiner" <streiner () cluebyfour org>
Date: Fri, 7 Jan 2011 10:31:57 -0500 (EST)

> The admins at this university claim this is by design and for security
reasons.. My response was the entire internet is asymmetrical and while this may of been a legitimate concern in the 90's, I don't think its a real concern anymore if things are set up correctly. They suggested we add static routes to our equipment to address this… This seems like a bad idea and I am not comfortable adjusting my routing table to address one site's issues on the internet due to their (not ours) routing/security policies.

Working in a university environment like you, we do have connectivity to some of those high-speed R&E networks, and or routing policy generally prefers to use those paths if they are available, for reasons of performance (offloading traffic from more traditional transit paths) and cost/cost avoidance, as others have mentioned. Asymmetric routing is always a possibility between two multi-homed networks. I still occasionally have to wrestle with the notion that many people have that asymmetric routing is bad...

If the organization at the far end is doing stateful firewalling at the borders of their multi-homed network, then they are probably accustomed to things 'just breaking' more often then they're willing to admit ;)

jms

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