I have just inherited a network which is running Cisco phones, a stack of 3750's, a Sonicwall router for data, and a Cisco router managed by our hosted voice provider. I was told that unicast traffic is being flooded on our voice vlan (5). I saw this via wireshark myself as well. I've been looking into this and have some clues.
First, our data traffic goes through a Sonicwall, the vlan IP for that traffic is 10.201.0.241/16. The gateway for those hosts are 10.201.0.1....
The voice traffic is on a seperate vlan, however there is no IP address associated with that VLAN....I guess the voice providers router handles it???? I don't know if that's configured correctly, that would be part one of this question.
Also, there seems to be no route between the routers. I can't even ping one of these pones from my data network, that doesn't seem right.
Also, now hold onto your boots, these ports are mostly all configured as trunk ports. The reason being that people need to be able to plug a PC or a phone into them without having to piggyback off of a phone.
Performance seems to be ok, but I need to figure this out.
I have ruled out STP as the issue as well as my mac table being too full. I believe the issue might have to do with asynchronous routing perhaps, but really I'm just a CCNA who's never had to troubleshoot anything like this before.
I would be so very grateful for someone's help on this. I've just walked into a new job and have this situation owning me.