Avaya phones with Cisco switches

[Marcelo Menchi]

We are trying to install a group of Avaya phones in our network (Cisco network) but I have a doubt about the configuration, actually we have next configs in each switch:

• default-gateway is the router of our LAN Data (10.6.140.1)
• VLAN data is number 2
• VLAN voice (defined in each switch now) is number 12
• WE installed a DHCP server in our Avaya Call Server (10.6.128.2) and the default-gateway (a firewall) is 10.6.128.1. 
• Each port has set switchport access vlan 2 (Data vlan) and switchport voice vlan 12 (voice vlan).

My question is,  how can I specify the dhcp server for voice vlan in that case? because when I connect the phones, they don't receive an IP address from the network 10.6.128.0

Thanks in advance

[Joseph W. Doherty]

Normally you would have an IP helper on the SVI (for both your VLANs, 2 and 12).

The DHCP server would have a scope defined for both your data and VoIP VLAN subnets.

[Marcelo Menchi]

Hi Joseph, thanks for your reply. In our case we have differents DHCP, DHCP server for data vlan is a windows server and the DHCP server for voice vlan is the Avaya Server (IP office). 

[Joseph W. Doherty]

If the Avaya server is on a different network from the VoIP phones, you still normally need an IP helper on the SVI. The difference being, the IP helper IP will then likely be different on SVIs for VLANs 2 and 12.

[Marcelo Menchi]

The Avaya server is in the same network, how the Avaya phone discover this DHCP to get an IP address?

[Joseph W. Doherty]

Cannot comment on the Avaya server, but the Avaya phones we use are configured to boot up on the native VLAN (which would be your data VLAN). Our data VLAN DHCP server provides them a DHCP option which tells them to switch to another VLAN, where they will ask for a new IP address on that VLAN when they swtich over to it.

It may be possible to hard set your Avaya phones to initially startup on your VLAN 12 (using tagged frames). You might check whether you're doing that if you're not doing what I just described.

[Georg Pauwen]

Hello,

have a look at the thread below, it discusses best practices:

https://supportforums.cisco.com/t5/wan-routing-and-switching/avaya-ip-phone-and-cisco-switch-config/td-p/2062552

[Marcelo Menchi]

Hi George, I saw these post few days ago but I can't understand DHCP option, that config is on the switch or AVAYA server_