c1800 and 100mb

We have two racks at a colocation and both are about 3/4 full. They have mail/file/app servers and 3 c1800's. There is a 100Mb internet connection running to a procurve switch. One of the 1800's goes to that same switch and the other two 1800's connect to the 1800 that goes to the procurve. Periodically(say every two weeks or so)one of the 1800's will lock up and we'll need to restart it(we restart them all when that happens). The 100Mb is a fiber run that terminates to a fiber/ethernet transciever. The ethernet runs from there to the procurve. We're wondering why we need to restart the routers. Snmp monitoring shows a periodic spike of 8mb and an average of 3 to 4mb over a 60 day period. I think it may have to do with the 1800's not being able to handle the 100Mb circuit. Would this be a resonable conclusion. thanks

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I would doubt that the router stopping is due to your uplink being 100Mbps.

When they run out of throughput, they just crap out on throughput, they don't keel over. You should pretty easily get ~40Mbps on an 1800 anyway with average traffic load.

I would have something logging the console of the router that hung. Maybe you'll get something alerting before it fails.

Check environmental conditions, overheating can cause any device to hang. Power spikes are another, but if its in a data center, power usually isn't so much an issue.

You may want to see if its the router itself that is hanging, or if the interface or feed is something wonky that resetting the router resets the feed.

Finally, try upgrading the IOS to a newer code base that still support the features you are using.

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Doug McIntyre

What router are you running and what IOS version? If you post the whole sh ver (maybe delete "Processor board ID") then all the info is there.

Console logging can be very CPU intensive. Obviously a few messages are OK but if there are a lot of messages then the logging process itself can hang the router. It's one interrupt per character sent to the serial port.

Obviously there will be cases where console logging is the ideal thing to do:)

If the router is crashing there may be crashdump files in the flash. they contain quite a lot of readable text.

You should check the CPU and memory use. Usual way for long/medium term monitoring is with snmp. The memory parameter you want to worry about it "largest free". sh mem ! at the console will do it.

If you post the output of sh proc cpu | exclude 0.00% 0.00% 0.00% when you think it might be busy then you might get some advice.

If IP input is busy then the router may be process switching. Fast switching is 10 times less resource intensive.

You don't say which 1800s you have however the 1801-1812 and 1841 seem to do about 70k packets per second. If the average packet length was

200 bytes then that represents a throughput of 112kbps. 1861 has double the performance.

Average packet length is likely to be larger than this.

Remember that a 100Mbps full duplex connection is

100Mbps each way. 200Mbps in total.

If you gather sh mem ! first few lines - 3 I think sh proc mem sh proc cpu | exc 0.00% 0.00% 0.00%

just after a reboot and also after a week or so someone here may have a look if you post them. just after a reboot

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These are 1811's and 1841's. I'll get a sh ver and sh proc mem and cpu's. Thanks

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I agree with the other posts, when the 1801 starts to reach a limit of what traffic can be passed, you will see service degredation, rather than a router failure. In addition to the other suggestions, could I recommend :

- connect the router to a serial console server, can you log into it when it is nolonger passing frames to work out what is going on ?

- are you syslogging the device ? What gets logged if anything before the units die ?

- Hopefully, you have access to Cisco support. Involve Cisco TAC and ask them for help. They may advise that you are tickling a particular bug, or have a faulty unit. If you are in the UK, we can help more with this option.

Best wishes, Andy

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Andy Davidson

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