877 ADSL Router - no 'show running-config'?

andrew.butterworth · ‎04-07-2008

I have an 877 ADSL router at home and I think I am hitting a resource/memory limitation. It is running 12.2(15)T4 Advanced IP Services and has 128MB of DRAM.

Yesterday I couldn't telnet (or SSH) to it (connection refused). Today I can telnet to it but when I type 'show run' there is no output, 'show start' shows me the saved config OK. It hasn't been rebooted, however I think rebooting it will fix it for the time being. It is however operating OK and all other 'show' commands seem to work. The only thing I can think of is I have done several large downloads over the last few days (some torrents and some just HTTP downloads).

Any ideas before I reboot it?

Andy

sundar.palaniappan · ‎04-07-2008

Andy,

It sounds like the router may be running short on memory. Have you checked how much free memory does it have? It's possible the router didn't have enough memory at the time you tried telnet or SSH yesterday and may be it had some memory room to let you in today. The only other thing I can think of, in addition to memory, that may cause this problem is IOS bug.

HTH

Sundar

andrew.butterworth · ‎04-08-2008

Hi Sundar

cisco-877#sho memory free totals

Head Total(b) Used(b) Free(b) Lowest(b) Largest(b)

Processor 830839AC 70764116 68799408 1964708 274416 52860

I/O 7400000 12582912 3528156 9054756 8800640 8797852

I am not too sure how to interpret that, but it looks to me like there is memory available?

Andy

andrew.butterworth · ‎04-08-2008

I just reloaded the router and for some reason some of the configuration has been lost - all the ip inspection has gone as well as the ips stuff. Obviously I had a backup of the config so I have re-applied most of the missing bits and its up and working again.

What I have noticed is when I enable IPS (via SDM) the memory just disappears and SDM stops and I can no longer telnet to it. If I connect via the console I see '%% Low on memory; try again later'. Obviously this is a memory issue, however I am not too sure why this has suddenly started happening. The router has been stable and has not been rebooted since 12.4(15)T4 was installed on 15th March.

Any ideas where to look next?

Andy

sundar.palaniappan · ‎04-08-2008

Andy,

It might be an IOS bug. 12.4(15)T4 isn't even listed in the bug toolkit but the funny thing is I see the earlier and later releases of the same IOS train. Normally Cisco would remove any image that has some serious bugs in it and could that be the case here? Can you try a more stable code and check whether the issue persists?

HTH

Sundar

andrew.butterworth · ‎04-08-2008

I think it is just a memory thing, I assume the IPS signatures are just getting bigger and so more memory is needed. I have therefore installed an additional 64MB DIMM into the 877 taking it to 192MB - standard PC133 Sync DIMMs by the way, however they need to be very low due to the faraday cage... - It seems to be behaving OK for the time being. I'll monitor it and see how it goes.

12.4(15)T4 is the latest IOS for the 877 on CCO and there are no warnings when you download it.

Andy

sundar.palaniappan · ‎04-08-2008

Never mind, I was looking at 12.2(15)T4. As I stated before it looked like one of two things - memory or bug. The 'show memory' output you had posted earlier showed plenty of free memory but you could still not see the configuration and that's what lead to me believe there may be an IOS bug. Anyway, let us know how it goes.

HTH

Sundar

andrew.butterworth · ‎04-08-2008

Hi, apologies there - it was a typo in my original post - the IOS is 12.4(15)T4 not 12.2(15)T4.

Thanks

Andy