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Configuration vlan on cisco switch with avaya phone


We are going to migrate to an IP avaya solution

We decided to dedicate a port for PCs, and another port for phones.

Our core switch is VTP server ( stack of 3850). We have created all the vlan on it (20 vlan data, 20 vlan voice).

Each vlan is configured like this:

interface Vlan235

 description XXXX

 ip address x.x.x.x

 ip helper-address x.x.x.x    

  ip helper-address x.x.x.x

 ip access-group xxxx in

we have 2 windows DHCP server, and an access-list


cdp is enabled on the core network and the distribution switches

On the DHCP server, we have a sub-network scope, and mac address filtering on each scope. DHCp option 242 is enable, configured and functional.

I have already deployed 10 Avaya IP phones, and it works.

The phones are powered by the poe


The problem is that there are a few offices where there is a lack of network sockets.

I would like to configure ports in voice vlan to use only one socket for some offices.

What is the best solution?

  Create (on the VTP server) a new vlan dedicated to this?
             SW1(config-vlan)#vlan 235 (If a vlan already exists with this ID, is it important?)

             SW1(config-vlan)#name Voice_VLAN

           Assign it an IP configuration (like the other existing vlans)
           Create on the DHCP server, a new scope, dedicated to this "Voice VLAN"?
Activate LLDP on all my switches( core is 3850 and distribution is 2960-x)? (CDP is already enable, It will not cause a problem for both to be enabled?)


           Configure the desired ports on the switch like this:
                SW1(config-if-range)#switchport access vlan 230

                SW1(config-if-range)#switchport voice vlan 235



Georg Pauwen
VIP Expert



Avaya requires LLDP (open standard), running both CDP and LLDP is no problem. Your approach is correct: create a voice Vlan, and assign both the voice and data Vlans to the same port.

Thank you for your help. I will test tomorrow and come back here, if I have a problem.

One more thing: make sure the ports are configured with 'spanning-tree portfast' in order for DHCP to work properly.


I tried the configuration

The cable is connected to the phone, and the phone is connected to the PC

On the PC, it works, I have the network, in the DATA vlan. But the phone  not working.

I have activated lldp on all the switches

add mac adresss of the phone on the DHCP SCope ( 235)


#interface GigabitEthernet4/0/2

#description AVAYA ToIP 

#switchport access vlan 111 =>DATA

#switchport mode access

#switchport voice vlan 235 => Voip

#srr-queue bandwidth share 10 10 60 20

#queue-set 2

#priority-queue out

#mls qos trust cos

#auto qos voip trust

#spanning-tree portfast