Switch is working but will not ping?

[Augusta1966]

Hi all,

I'm fairly new to all this so please go easy!

I have a 2940 switch which had the wrong VLAN on it (the equipment we had running through it hadn't been used for a while & no one noticed it wasn't working until now).

I found the switch port was still set to an old VLAN, changed this and made sure it had the correct default gateway. Once all the changes had been saved, the switch & pc ip addresses were now able to be pinged. However, back in the office (15mins later) pings have stopped to the switch but not to the pc (which is working!) the switch ports are initialized.

Have you any advice on how I can get the switch to ping again as normal? Or what I could check to see why this has happened.

Many thanks

[Antonio Knox]

If you have a ping check running to this switch, make sure that the SVI (interface Vlan###) configuration is still good.  If by 'had the wrong VLAN on it ' you mean the Vlan interface ip address was bad, you will need to update the ip address for the pings that are going to the switch.

Rate this post if it helps.

[Augusta1966]

Hi Antonio,

The 'wrong vlan' was on a particular port of the switch. What I find odd is that a pc in that office which is plugged into the switch I can now ping but the actual switch itself I cannot. Any other pointers would be great.

Thanks

Conor

[cadet alain]

Hi,

Could you make a quick sketch of your network indicating the working ping as well as the failing one

Then also post your sanitized config  from 2940

Regards.

Alain.

[Antonio Knox]

I'd suggest verifying the vtp mode (typically you would want client).  With ip changes running in transparent can cause some issues.  Also, if an access vlan is configured on the trunk of upstream switch that can affect how this works as well.  As cadet suggested, you should post a sanitized version of your config.  Problems like this are typically easy to diagnose once a second set of eyes have been put on the config.

[Augusta1966]

Hi Guys,

Thanks for your help. The setup from show version and show running-config is attached.

Interestingly when I reboot the switch both it & the pc attached to it ping from the pc back in my office. However, after 10mins the switch times out but the pc continues to get replies from & it connects to the network! The pc attached to the switch has an ip of 172.18.3.222

Thanks

[ARMANDO ALVARADO]

I saw your config and there are some items missing on it. Or did you edit it. Where is the spanning-tree portfast for your pc and the trunk port is not correctly configured from what I saw. Are you using any native vlan on your trunk. ? or on the other end.

[cadet alain]

Hi,

The portfast feature is not mandatory  and when not explicitly configured the native vlan is vlan 1

Regards.

Alain.

[cadet alain]

Hi,

You didn't provide a diagram of the network topology with location of PCs pinging each other( switch port, router or other switch,etc.)

And I don't think the show version is gonna really be of any help here.

Regards.

Alain

[Augusta1966]

Hi guys,

Thanks again for your help.

Aalvarado - No, I didn't edit the config I posted

Alain - Attached is a little diagram of the switches to the pc. Is there any command that I could use on telnet to provide you with more info, if the 'show version' isn't suitable?

Glen - The pc that is working has a gateway of 172.18.1.1

Why would the switch initially start pinging fine, then time out?

Thanks

[cadet alain]

Hi,

Can you put the interface ids on the sketch and position the other pc as well as the gateway of 172.18.1.1

Regards.

Alain.

[Antonio Knox]

Add:

int fa0/9

switchport access vlan 91

Don't worry, it won't break the trunk.

[cadet alain]

Hi Antonio,

Could you explain how this can solve the problem?

Int vlan 91 is already up/up and not pruned otherwise there would have been no communication with the switch from start?

If the interface is in operational mode of access then it will change the vlan from 1 (default) to 5 but then how can it improve the problem as the 2 PCs can ping already? And if the interface is in op mode of trunk this will not change anything.

Regards.

Alain.

[Antonio Knox]

Short answer......it worked for me when I ran into this issue a while back.  Just one of those things, man.

[glen.grant]

  Switch default gateway pointed to the same gateway as the pc client that is working ?  Also check for any IOS bugs for the switch version you are running.