Showing results for 
Search instead for 
Did you mean: 

CUCM Blade and VLANs


We're running a 4351 with a E160 blade with CUCM 11.5. I've noticed that phones on the voice vlan can't talk to the UCM. Should CUCM be able to work on the same VLAN as the phones? The phones can talk to the router. CUCM can talk to the router. But CUCM can't talk to anything on the voice vlan but the router. This is with IPv6. I've not read anything about CUCM needing to be on a separate VLAN from the phones but this is acting strangely.



4 Replies 4

Mohammed al Baqari
VIP Advisor VIP Advisor
VIP Advisor
It should work fine. Can you ping any of the phones from cucm.

I can't ping anything in the voice vlan from the CUCM except the router. I can also ping devices in other VLANs from the CUCM, it's only in the VLAN the CUCM's ip address is on that I see this problem. If I create a new VLAN for the phones so they are not on the same VLAN as the CUCM then they can talk to the CUCM.  If I plug a PC into the voice vlan I can ping the phones and router but not the CUCM. But from the router I can ping everything.


Everything I'm testing with connects to a switch module in the 4351.

Check if your router is performing proxy-arp in cucm vlan. This seems to be
the case which is preventing the communication. Try the command no ip
proxy-arp on the router interface of the cucm then test

Rising star
Rising star
CUCM can be on same VLAN no issues on that.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers