Catalyst switch hangs when connecting via console port

[ctwohill]

Hi,

I've just started work for a company - they have no network documentation or knowledge of their current set-up whatsoever.

For the LAN in the office they have Cisco Catalyst WS-C3524-XL switches. But it doesn't seem like these are even configured with an IP address for management purposes.

So, I thought I would connect via a console cable to have a look at their configurations and also to investigate some performance problems some users were having on the LAN.

BUT - when I connected to the console cable, all the switch LEDs stopped flickering happily and went solid and everyone in the office lost their network connectivity! (I wasn't popular!)

Rebooting the switch with the console port still connected had no effect - the LEDs remained solid and there was no network connectivity. However, when I removed my console cable, everything started working again!

Does anyone have any ideas a) what can have caused this and b) how I can resolve this problem and connect to the switches without disrupting all the other users!

Note: I subsequently connected to a spare WS-C3524-XL switch using the same laptop and same console cable without any problems.

[amit-singh]

Hi,

Seems to be a strage problem. Are you able to login to the switch when you have console cable connected. Do you see the prompt on the hyperterminal window ???

If you are able to login to the switch then I would suggest you to upgrade the software to the latest one which 12.11 WC5 new for the 3500 Xl's. That should make a diffrence.

HTH,

-amit singh

[ctwohill]

Hi,

thanks for the response.

no, I can't login to the switch(es) at all. There seems to be no response from hyperterminal at all. (Then I noticed that the LEDs had gone "solid" and that everyone started to complain they had lost network connection!)

Even when I powered off and powered on the switch with the console port still connected, nothing appeared on the hyperterminal screen.

However, as mentioned, I'm able to connect to one of our spare switches using the same settings, same laptop, and same console cable - so I guess that would rule these things out as being the cause?

Its definitely a strange one, especially as it seems to be affecting all 3 of the live switches!

[amit-singh]

So you mean that if you connect the console port to one switch all the other switches losses the connectivity also ??

Are you sure tha none of the switches has any kind of IP addreses.

Did you try connecting the console to any other switch. Do you see the same symptoms. Try connecting the console cable to any other one and see if that works ok.

I would suggest one more thing to try disconnecting the switch on which you are facing the probelm from the network say in late hours and then try connecting the console cable.

regards,

-amit singh

[ctwohill]

Hello all,

looks like I've found the problem - it seems to be a faulty port on my laptop!

Its still very bizarre though - If i connect to the switch using the port on my laptop port replicator then its fine. When I use the port on my laptop directly then I get no response. (I don't really understand that though as I thought all the port replicator did was replicate my laptop ports so if anything I would have expected it not to work with the replicator! But its the other way round)

I tried with a couple of other people who have the same type of laptop and it works fine with their machines. Strange, but at least I seem to have found the cause of the problem!

[amit-singh]

Now atleast you can relax and do your work.

-amit singh