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New Member

Routing Problem.

I have three networks, and configured on my Cisco 2600 series router that is connected to the internet. I configured the the on fastethernet 0/0 and configured and on fastethernet 0/1. It has been working perfectly for a long time now but recently the systems on network connected to fastethernet 0/1 port will either stop browsing or it will be very slow. I've checked my configuration and everything is ok. I've changed the cables and is still giving the same problem. meanwhile the systems on network are working perfectly. Any idea on this? I'll appreciate any input from all of you.


New Member

Re: Routing Problem.

Have you noticed a significant increase in CPU, Interface counters (errors), buffers overflows...

Are you running any baseline products so you can see if traffic has increased? Sounds like routing is ok because everything is directly connected. I tend to lean towards virus/worm traffic or a chatting NIC. Use a sniffer and look at the traffic patterns.

How many switches or hubs do you have connected to F0/1, maybe some STP issues or broadcast issues.

Take a look at this, but use a sniffer and look at the interface for problems.

New Member

Re: Routing Problem.

Agreed. Use of the following commands should also help point out any problems:

show proc cpu (to see how hi your CPU load is)

show interface switching (will show you what's CPU vs. Fast Path switched)

Also, you didn't mention how you're connected to the Internet? Are you NAT'ing? That might be a problem for recently infected machines where they generate what amounts to a DoS from inside your network. Try putting a couple of ACLs on ICMP and see if that's getting a lot of hits (if it is then you have infected hosts likely Nachi)...also try and look for internet traffic destined to port 80 from a single sourced machine but to a lot of different hosts. Those are teh symptoms of the most recent viruses which can cause your router problems if you're NAT'ing.

good luck.


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