Pinging 2950 problems/TTL=253. How do I change this ?

[FWHATER]

I just a got a Cisco 2950 switch. When I directly connect to my 2950 switch, I get persistent replies when I ping. When I connect my switch to a 2600 router, the replies are spotty and the ttl is 253. Everything else replies with a ttl of 126. How do I change the ttl for the switch and wil this help ?

 

[KiscoKid]

Changing the TTL won't help as different devices generate different TTL's when they generate an ping response.

For example, some old Windows OS's used to generate a TTL of 32, now they generate a TTL of 128. Cisco devices generate a TTL of 255.

The actual problem you have could be a physical cabling, interface and/or speed/duplex issue between the switch and router. Check the interface of both the router and switch port it's connected to using the 'show interface' command. Also ensure that both devices are either set to auto duplex/speed or they are both locked down (i.e. 100mb full duplex). Locking down one device and not the other can cause comms problems.

If that doesn't help, maybe try a different physical cable and switch port.

 

[vipergg]

the spotty replies as kisco indicated is probably a speed/duplex mismatch between the router and switch . the router is probably hardcoded and the switchport was left as auto which give you a mismatch.

 

[FWHATER]

Thanks for the help, folks. Turns out, there are compatibility issues between NM-4E on 2620's and Cat 2950's. No matter what changes you make to the interfaces on either device regarding speed and duplex, you will suffer severe packet loss. I plugged that same 2950 into another 2620 fast ethernet 10/100 and experience no packet loss.

 

[JOAMON]

If you port match the router and switch and set both to 10 full you should not have any problems. You probably need to set all four ethernet ports to full duplex.

 

[baddos]

Remember that TTL has nothing to do with packetloss or speed. TTL is just a failsafe in case you have a routing loop, so that a packet won't continue forever.