3750: Can't connect to stack (Console Cable / Telnet) - Memory Issue

[Alain Cloet]

Hi,

As the title says, I can't connect to my stack over Telnet nor via the console cables (serial).

When I try to connect via telnet, I just get a time-out.

When I try to connect via the Console Cable I get the lines "Switch con0 is now available" / "Press return to get started".  However when I do press enter, I have to wait for a while and the same lines return (tested on some of the stack members ; not all). 

The best info comes from the 'Stack Master' ; via the console cable, I get an error '%% Low on memory, try again later"

I can't connect via HTTP-either (but I don't think that was enabled, if even possible), so I really don't know how I can get to the switch stack to reconfigure.  I don't have any functional problems, it works, but I can't connect to change any of the settings ... We had a power problem with some computers/servers last week ; my guess is that the 'connections' still seem to be open and thus not allowing new connections, but I 'm not sure if that would cause that the console connection doesn't work either...

I can't think of how much longer to wait - it must be over 12 hours already - so I guess the 'try again later' isn't an option anymore ....

Plan B is to power off all switches in the stack, and power on again ; but I'd rather have a Plan A ... But I can't think of any real options for a plan A (maybe SNMP could do, but I don't think there is a RW-account enabled ... but if it would, I still wouldn't know what to check, or what to do)...

Any of you ever had this problem, and is there a plan A possible ?

And can I retrieve the reason for the memory problem if I would do power-cycle of the devices ?

TIA,

Alain

[lgijssel]

Hi,

I'd go for plan B to start with and only break my head over what else may be wrong when the situation does not restore to normal after that. But then, that's just me.

regards,

Leo

[Leo Laohoo]

1.  Disconnect ALL the stack cable;

2.  Power down the stack

3.  Connect a console cable to the stack master and log everything;

4.  Power on the stack master;

5.  Once the stack master has powered up, connect the stack cable to the next and power that one too.

6.  Repeat the process until you get the entire stack powered up ONE AT A TIME while logging everything.

Please post the output.

[glen.grant]

    Yes we have seen this on 3750's before , unfortunetly your only recourse is going to be to take downtime and reload the stack to free up the memory  and once its back think about getting newer code if its older.

[Alain Cloet]

Thanks for the info ... could do this yet, as this stack is rather important ; and I can't just turn it off during the week...

The good part is it still works, and for the urgent 'change' I repatched to a switch I can connect to...

At the moment the stack consists of 8 WS3750C 24-port switches (combination of POE, GBIt, SFP) ... Is this too much already ?

[Leo Laohoo]

At the moment the stack consists of 8 WS3750C 24-port switches (combination of POE, GBIt, SFP) ... Is this too much already ?

Personally, I wouldn't stack a 3750 no more than 6 switches in a stack.

[Somasundaram Jayaraman]

Hi,

Please do a reload and check whether the issue occurs again or not.

I also came across two bugs.

CSCtd19039 & CSCsv32556

Please check whether we are hitting the above bugs. I dont have information regarding the IOS you are running

Hope this helps

Cheers

Somu

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[Hamilan Gnanabaskaran]

I am getting the same issue. After some time when I keep console connection found FIB-2-FIBDOWN loggs.

   %% Low on memory; try again later

15w0d: %FIB-2-FIBDOWN: CEF has been disabled due to a low memory condition. It can be re-enabled by configuring "ip cef [distributed]"

I have 3 stack sin the switch. It is my L3 switch and have around 4K routes in EIGRP.   AS the memory is low, I am planning to send only summary routes there and do a reload.. Any sugession..

[Leo Laohoo]

%% Low on memory; try again later

This is an indication that the IOS you're using is buggy.  You need to consider upgrading your current IOS.

If your stack is running Layer 3, use IOS version 12.2(55)SE8.

[Hamilan Gnanabaskaran]

After reloading the switch, I was able to login. Let me check Leo. Thanks for the info.