I have a 2821 rtr serving up ip addresses to some 7961 phones all connected to a 3560-48 port switch and everything has been working great.

The other day the 3560-48 power module went out so no POE.

We can get the phones online with local power and the 3560-48 which is great.

However I decided to replace the 3560-48 with a 3560-24 from our offline stock instead of installing another 3560-48 since the 3560-48 is way more than this site needs.

The 3560-24 loaded up and when it is installed it comes online just fine.

I can telnet to it, ping from it to anywhere in our network, and it delivers POE to the phones.

Other than having fewer ports on the 3560-24 the config is the same and the IOS is the same as the 3560-48.

However the 7961 phones will not pickup an IP address when the 3560-24 is online.

When the 3560-48 is installed again and the phones are plugged into local power they pickup an address from the router just fine.

Any ideas?

Hi,

Check out the configuration are same for  DHCP in the new switch for ip phone.

HTH

Ganesh.H

   Verify  port configs for each match  what was on the old model.  Portfast turned on ?

Yes I did a write erase before loading a fresh config in the 3560-24.

The rtr is acting as the dhcp server and the 3560-24 has a default route to the rtr and also a voice vlan configured.

Everything on the 3560-24 config is the same as the 3560-48 other than there being less ports.

We did line by line comparison of the configs and everything is the same.

I am going to reload a fresh config in the 3560-24 again and bring it online as a second switch and work with it that way.