install cisco switch for voip

tolinrome used Ask the Experts™
I have a new 2960S poe switch and need to connect it to my lan for voip, it will be the first voip switch. I will be connecting it to my catalyst 4507R. I need help in how to configure it from the beginning. I will connect the new switch to the 4507 with a regular ethernet cable - what do I do after that? I heard I need to trunk the ports, any 2 ports? How do I trunk them? How do I create the voip vlan? All ports on the switch will be for voip. I also need to put a dhcp server on the new switch (vlan?) so the IP phones can receive an address, how? What do I use as the default gateway?
Once I install the switch how do I log into it to set it up via telnet?

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You do relize that just putting in those switches does not offer VOIP. You need a PBX that gives you the VOIP, I assume you have that setup. The PBX that is your VOIP "router" will be the gateway, and also the DHCP server. Your VOIP switches are there just to give your phones connections to the PBX. Also make sure QOS is enabled on your switches for the VOIP.


yes, we have an avaya ip office system now and the vendor is coming in to enable it for voip. The ip office system is already connected to the lan via the switches. I need to know how to configure the new 2960s switch so the voip users can use their IP phones. So on the switch you're saying I do not make it a vlan or enable dhcp serve on it? How do I make it QOS enabled and all the other questions I need answered as my first post? I'm literally doing this from the beginning, I took the new switch out ofthe box and need it configured. Thank you.
The Ip Phones are just devices like anything else, when plugged into the switch they will just work like any other device. Your vendor will setup the DHCP to hand out addresses to the phones which will get IP address, Gateway etc. Once they get an address they will know where to go to get the VOIP. The QOS setting should come turned on by default make sure the switch offers QOS if not I would get ones that do, VOIP is really depenedent on QOS. Your vendor should also really help with the setup of the network, it is very easy pretty much plug and play the real configuring takes place on the PBX.


ok, so thats good news, I wanted the voip phones on a different subnet (vlan) than everything else on the network. Good to know the vendor will do most of the work. Can yu help me answer the other questions I had in the original post?

I need to connect the switch to the main catalyst, I was told to trunk the 2 ports and connect with an ethernet cable, how?

I need to configure the switch as a VTP client, how?

I need to be able to telnet into the switch to issue these commands, how?

Here is a guide for you to follow, I highly recommend using the cisco site for most of your questions too.

To setup Telnet on your Cisco Switch connect using the direct method (blue cable) that goes to the serial port of your PC. Again grab a Cisco book for the commands you will need plus reading the book will help you learn it.

To subnet your VOIP Network you do not acheive that using a vlan. VLAN sorta does Subnet for you. If you have your data and VOIP on the same ethernet lines you would just assign a different IP pool from the PBX to the phones, but if your Switches are being shared with other devices and the IP Phones you would filter the DCHP by MAC address.


I spoke with my vendor and they can, bit highly do not recommend doing the dhcp on the phone system, they have had much more success doing it on the switch.
Always follow the recommendations of the vendor especially with VOIP.

Check if your switch offers the ability to offer DHCP not all do mostly newer ones. The text below just swap out router for switch if yours does offer it.

To configure Cisco IOS DHCP, follow these steps, which include sample commands:

Configure an IP address on the router's Ethernet port, and bring up the interface. (On an existing router, you would have already done this.)
Router(config)# interface ethernet0/0
 Router(config-if)#ip address
 Router(config-if)# no shutdown
Create a DHCP IP address pool for the IP addresses you want to use.
Router(config)# ip dhcp pool mypool
Specify the network and subnet for the addresses you want to use from the pool.
Router(dhcp-config)# network /8  
Specify the DNS domain name for the clients.
Specify the primary and secondary DNS servers.
Specify the default router (i.e., default gateway).
Specify the lease duration for the addresses you're using from the pool.
Router(dhcp-config)#lease 7
Exit Pool Configuration Mode.


" If you have your data and VOIP on the same ethernet lines you would just assign a different IP pool from the PBX to the phones, but if your Switches are being shared with other devices and the IP Phones you would filter the DCHP by MAC address"

Were not going to use the PBX for DHCP. Currently all our vlans go through the same ethernet, I have about 10 vlans already accross 6 different switches and all lan data goes accross the switches. the IP phones would be connected straight into the voip switch and there will be a port on the IP phone to connect the computer as well. They want  the voip phones on a seperate, on its own subnet for QOS.

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