Mitel SX-200MX and 3Com 4500 Switch's

[strai81]

Hello,

We have a Mitel SX200 and are using 3Com 4500 switch's. I am hoping someone here can help me out with what I believe is a DHCP issue. Our network has no VLAN's configured, and we are spread out over several buildings on site. Each building with it's own switch or switch's. DHCP server is configured with Options 128, 129, and 130 and operates off of an IBM As/400.

As everything sits right now, all IP phones boot up and work fine. However it's necessary for the voice and data traffice to be seperated, and that's where the problem begins.

Going to the 3Com switch's we added the OUI of the Mitel phones to the switch's, created a Voice VLAN and enabled each port to be tagged to the Voice VLAN. The switch detects the phones and adds the port to the VLAN.

But, when someone picks up an IP phone and calls an IP phone in another building, the phones ring but neither person can hear anything. Calling IP phone to IP phone in the same building works fine, just two IP phones connected to two different swith's try to talk, nothing can be heard.

I believe the problem is partially DHCP and partially switch config, and 3Com doesn't know and I can't get in touch with anyone from Mitel.

Any suggestions would be appreciated.

Thanks,

Steven

 

[paterson]

I had to read your post twice because I do not see any mention of a router. Is it possible that the 3COMS are layer 3 devices?

When you have a problem of "No Audio" either one way or two way, the problem is almost always with a router. Either it is missing, programmed incorrectly, or the IP phones have the wrong router/gateway IP address given via DHCP.

The fact that your IP phones will work on the same switch but not when talking to other IP phones on a different switch tells me that you do not have a router on this network, or at the very least, a router that is not programmed correctly. When you implement VLANS a ROUTER is absolutely essential.


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[strai81]

Thanks for your reply paterson. You are correct that the 3Coms are Layer 3 and that there is not a router. When I spoke with 3Com I asked if I needed a router and the tech said no because of the Layer 3 and the voice vlan being tagged.

 

[paterson]

Okay then, now knowing that opens up some more questions.

What is the VLAN ID for the Voice VLAN? This value needs to be provided to the IP sets as DHCP option 132. Once the IP set recieves this value, the original DHCP IP address from the Default VLAN will be released and the IP set will then request a new DHCP address from a DHCP server on the new VLAN.

Also, do not provide DHCP option 132 with the second DHCP server, the IP set already has that option from the first step.

What is your Gateway/router IP address for the Voice VLAN? This address needs to be given to the the IP sets as DHCP option 3 in this second DHCP step. This IP address will help your IP sets in communicating with other IP sets on different switches.

Typically, I will ask the customer's IT guy to provide the Mitel specific DHCP options from their DHCP server for the sets booting on the default VLAN (usually the Data VLAN). Then I will use the built in DHCP server on the 200 ICP to provide the voice VLAN IP address to the Mitel set. I like the seperation it provides.

WARNING-: Make sure that the switch port the Data VLAN DHCP server is connected to ONLY has access to the DATA VLAN not the Voice VLAN. Also, make sure the switch port that the Mitel 200ICP ONLY has access to the Voice VLAN traffic. You can make the VLANs talk to each other, that is okay, but you cannot have the two DHCP servers on the the same VLANs. Trust me, it will cause a conflict and sporatic problems.

The bottom line is that the IP sets do not know how to get to other IP sets.

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