CISCO 2611 ROUTER FREEZES AND NO NETWORK CONNECTIVITY

[ganeshSE]

Hi-

I have a 2611 router connected to a 2950 switch for our internal LAN. Quite recently, the router is working weird. It looks like it has frozen and we loose network connectivity. even if internet exists our emails and some applications stops working.

The ACTIVITY LED keeps flickering constantly at a much higher rate and that is what i assume as frozen. I do not know what is exactly going on it. I had to manually shut down and power up the router everyday for it to work. I know, this is crude of way of doing and I cant keeping on restarting the router everyday.

I appreciate your valuable suggestions and solutions. SInce this brings our whole network down, it is an emergency.

Thanks

 

[vipergg]

You may have someone who is infected and overunning the network . I would be rseally be suspicious if the activity led is running faster than usual.

 

[andreyts]

Check with some fre Sniffer like eherial for brodcast storm!!!!
Maybe you have some virus on the network...

Best Regards,

Andrey
CCNA

 

[KiscoKid]

The virus infection the other posters have mentioned is a possibility. If it is a virus, check the utilisation of the device (using a tool like MRTG or Concord) to verify the interface utilisation or CPU. If the interface utilisation is low, chances are it's not a virus.

It could also be a software or hardware fault. Try enabling syslog on the router and check the logs it generates immediately before it crashes. If there is no meaningful log generated, try creating a core dump and place a call with Cisco TAC for their assistance in diagnosing the dump for you.

 

[JOAMON]

Check a couple of things. From past experience with this combo make sure the 2611 is set to full duplex and that the switch port it is connected to is hard set to speed 10 and full duplex. Another thing that might crash the router is if your default route is set to an ethernet interface and not to the ip address of the next hop router. The arp cache can get so big as to crash the router. Do a show process cpu and a show process cpu history and see what or if your CPU is getting overwhelmed. Could also be the IOS.

 

[JOAMON]

If you are using Cisco Network Assistant with your switch you can look at the port statistics page to see who is slamming the network.