vlan network setup for cisco voip phone

Posted on 2009-02-09
Last Modified: 2012-05-06
Hello experts!

We are trying to implement hosted voip system and we will have P2P t1 for phones to voip company and another existing framerelay T1 thru different ISP. In order to save cost of cabling and making walljacks for each phone, I'd like to use existing data line and create a vlan using cisco 2960 switch as shown in diagram attached. Please advise if this topology would work as shown in diagram.
1. Would sonicwall be still functional as dhcp server for data line? TZ190 does not recognize 802.1q.
2. Phones will get dhcp assigned from hosted voip company thru the router on the right. Would there be any problem w/ that?
3. Is access port and trunk port configuration on diagram correct?

Thank you so much in advance.

Question by:hope0823
    LVL 32

    Accepted Solution


    Your configuration is called a Tandem config, the phone has a built in switch and there is a data and VOIP vlan trunked to via the upstream switch. This is a viable design and is a recommended design by Cisco.

    1) The sonic wall could still provide dhcp services for the data vlan becuse there is still layer 2 connectivity from the hosts to the sonicwall data vlan interface, that has not changed.

    2) Phones will get dhcp services if the VOIP router terminates the layer 3 interface for the VOIP vlan and that interface is configured to provide dhcp services.

    3) yes

    Should work fine,

    harbor235 ;}

    Author Closing Comment

    Thank you so much Harbor235. :) i will test it and will post the result.

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