Re: 7940/7960 cannot be moved to a different VLAN

mhanderson · ‎10-18-2001

We are running CallManager 3.0(8) in an eleven story building with approx 1200 phones. Each floor has a 6500 for an access switch which converge at dual 6500s (w/MSFC) at the core. We thought it would be a best practice to give each floor a separate data and auxillary VLAN. We have users who are switching floors and taking their 7940/7960s with them. This will place their phone on a different voice VLAN. Just plugging the phone into the new switch does not work. Also, reseting the phone (**#**) does nothing. We have to go to the Network Configuration on the 7940/7960 and release the DHCP address and re-initialize the phone.

Is this how it is supposed to work or do we have the 6500s misconfigured? I/we were under the impression that we could move the phones anywhere on the LAN with out any re-configurations.

Mark Anderson

dgoodwin · ‎10-18-2001

You should be able to move the phones without a problem. This sounds like a config issue on the 6500 to me.

mhanderson · ‎10-19-2001

We also think that it should work, but it doesn't. The 6500s are setup almost exactly from a cookbook. What kind of information gathering do you think we need to do? I would think that CDP would have cleared this during the port to phone setup.

TIA

Mark

dgoodwin · ‎10-19-2001

When you go to the network configuration after you have moved a phone, does it show in option number 19 that the Operational VLAN Id has changed to the correct value for that particular floor? Just curious. Also, do you have portfast enabled on the switchports the phones are connected to?

I also wonder if you move a PC (e.g. notebook) to a different floor, would it work correctly without doing anything special?

In any case, what I would suggest is to make sure Forwarding Delay is set to NO on the phone configuration, plug a PC running sniffer software into the PC port, plug the phone into the wall and start the capture. We should be able to figure something out from the sniffer trace.

mhanderson · ‎10-23-2001

Hmmmmmm. It appears that DHCP is returning the old IP address. Funny that it only happens if we don't release the IP address from the phone. We are now looking into IP Helper and DHCP on the CallManagers. Any ideas?

paul.harrison · ‎10-23-2001

Try restricting the vlans allowed on the trunk from the core switch.

You say you have a different Vlan for each floor (I assume a different Aux VLAN also) are you running all vlans on the trunks to all switches? It could be the switch is seeing the phone attempt to connect to a Vlan the switch knows about so allows it through (something to do with the way the phone sets up trunking).

However if the switch doesn't know about the Vlan then it should force the phone to request a new one and subsequently a new IP address.

just a thought!

paul

walkerj · ‎10-29-2001

We had the same problem with phones and laptops set to dhcp. Turned out it was a known bug with Win 2000

server. Dhcp scopes configured under a superscope will not release the original dhcp address. When you move to a different vlan you still get the original address. We reconfigured individual dhcp scopes with out the use of superscope, and this solved the problem. This was approximately three months ago.

I hope this helps. Jack Walker

mhanderson · ‎11-01-2001

Hey, that was it! We owe you some cold ones. How did you figure it out and is there a fix from Microsoft? or is this just another feature from Bill & Co.?

Thanks again,

Mark Anderson

walkerj · ‎11-01-2001

We called Microsoft on one our $500 tech support calls. They admitted it was a not too publicized KB

(known bug) and at that point no documentation was actually available through support.microsoft.com.

Needless to say we didn't get charged for the call.

Glad I could help!

Jack