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New Member

3750 and 3560 Config problem

We've got 2 switches in one of our offices, we recently installed IP Telephonny in this office. For the first few weeks, they were using our main office server as pstn, last week we installed them a local pstn, since then the phones randomly disconnect and reset without any warning or message...

We already have few other offices with the same configuration withour ever any problem. I am attaching my 2 switches config... I'm sure something is wrong but I can't see it.

on the 3750:

ports 1 - 2 redundant wan connection

ports 3 - 4 redundant pstn (4 actualy NC and Shutdown)

ports 6 - 10 Servers and other HW

11-24 Workstations and IP Phones


All IP Phones and workstations

they are both linked with a 1Gb SFP


Re: 3750 and 3560 Config problem

Are you using PoE or power bricks? What IOS?



New Member

Re: 3750 and 3560 Config problem

Yes we are using PoE however the load is below 20% on the 3750 and below 50% on the 3560

I am using IOS 12.2(25)SEE2 on both

New Member

Re: 3750 and 3560 Config problem

Just a quick check...are your phone and computers receive the ip addresses from the same subnet?

You've the phones and phone ports assigned to Vlan200, but the "interface vlan 200 and its ip" is not defined any where in both switches. Try adding it to the switches. Your phones would receive an ip address from vlan 200 while your computers receive the ip from vlan 100.



New Member

Re: 3750 and 3560 Config problem

The phones are NOT on the same subnet, and you are right! htere is no address for the vlan200 subnet... wich can be a problem... I'll assign an ip to that vlan and will see.

Thanks! I will post back if this worked.

... However I cheked our other ofices and there are no IP on our others switches for this vlan... do I HAVE TO assign an IP to the vlan? on each switch?

New Member

Re: 3750 and 3560 Config problem

Yes, it's best that you assign an IP to the VLAN for voice and data separately.

Were you able to verify that the phone's ip is different from the computer's, eventhough you didn't have vlan200 ip specified?