Downloads stall with ip inspect enabled

[TravisTauzier]

I've been trying to figure this out for some time now.  I have a network setup with a couple of users, as well as a few servers.  I'm using a 3640 as my border router that is connected to a 3750 with L3 routing enabled.  I am using the IOS firewall in the 3640 and am having problems with downloads and connections in general on the LAN.  Downloads will start at fast speeds (~1MB/s) but after a short time, it will begin slowing to a crawl or idle.  I have disabled my ip inspect rules and found that the downloads will function at full speed for the entire download.

I've looked over the router configs several times, and I don't see anything unusual.  Is there anything I should be looking for?  I would like to think that this router can handle the traffic of about 5 computers.  If I'm wrong please let me know.

TravisT

[wzhang]

Hi,

With this kind of forwarding plane issues, one of the key steps in troubleshooting is to narrow it down to a specific feature running on the IOS that's causing the problem. Ie., start out with a clean baseline config when you don't have any problems. Add one L3 feature at a time to the interface and re-run the same test until you start to see the problem, and then focus on that feature to understand what it has to do with the flow in question. With this particular issue, if you were to remove the inbound ACL, does the problem go away?

Thanks,

Wen

[TravisTauzier]

Wen,

Thanks for you continued help with this.  I will bring everything back to the most basic possible setup and work from there.  The only issue I see with this approach is the problems appear to be intermittent, so without knowing what is triggering these problems it may go unnoticed.  I can't say that I've ever seen 25MB/s speeds through the router, but at times I've seen close.  The cable internet speeds also seem to fluctuate a good bit depending on time of day, etc, so that adds another layer of complexity.

Travis

[schaef350]

What did you end up finding as the silver bullet to solve this?  I am having a very similar issue on an ISR 2921 today.