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Voice VLAN - Cisco IP Phone - CDP


Userlevel 1
One of my customer is connecting Cisco IP Phone with Extreme switch but it is not getting register automatically because of its default VLAN 4095. Do we need to change VLAN of IP Phone manually or it should workout with CDP?

5 replies

Userlevel 6
Hi Waqas,

Although EXOS supports CDP the feature what you are looking for is not available yet but you can determine if the phones supports LLDP and switch can advertise the VLAN via LLDP or you can assign the VLAN manually.

Here is the link to Article on configuring LLDP
Userlevel 1
Karthik Mohandoss wrote:

Hi Waqas,

Although EXOS supports CDP the feature what you are looking for is not available yet but you can determine if the phones supports LLDP and switch can advertise the VLAN via LLDP or you can assign the VLAN manually.

Here is the link to Article on configuring LLDP

Hi Karthik,

Thanks for your feedback. In case of complete Cisco setup (Switch + IP Phones), CDP works and register the IP Phone with CCM without manually changing the VLAN of IP Phone (Default VLAN 4095). Whereas, when they are connecting Cisco IP Phone with Extreme switch, CDP is not showing IP Phone as neighbor but after after configuring LLDP and changing IP Phone VLAN to specific voice VLAN on network, it works fine.

Now customer's reservation is on changing the default VLAN which is not viable in case of 100s of IP Phones.
Userlevel 6
One comment. Vlan 4095 is reserved by IEEE 802.1q standard. Not all products and not all vendors do support 4095 as other vlans. Not sure if this can be issue here
Userlevel 1
Pala, Zdenek wrote:

One comment. Vlan 4095 is reserved by IEEE 802.1q standard. Not all products and not all vendors do support 4095 as other vlans. Not sure if this can be issue here

Thanks Zdenek for your valuable feedback.

Does Cisco support 4095 as other vlan?
Userlevel 6
Hi Waqas, please check the articles below for some additional information:

How to configure LLDP for Extreme switches to recognize IP phones

https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-LLDP-for-Extreme-switches...

What is the EXOS equivalent of the Cisco 'switchport voice vlan' command

https://gtacknowledge.extremenetworks.com/articles/Q_A/What-is-the-EXOS-equivalent-of-the-Cisco-swit...
Userlevel 1
Henrique wrote:

Hi Waqas, please check the articles below for some additional information:

How to configure LLDP for Extreme switches to recognize IP phones

https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-LLDP-for-Extreme-switches...

What is the EXOS equivalent of the Cisco 'switchport voice vlan' command

https://gtacknowledge.extremenetworks.com/articles/Q_A/What-is-the-EXOS-equivalent-of-the-Cisco-swit...

Thanks Henrique for your feedback.

Please let me know why CDP is working on Extreme switch as it should. Whereas, LLDP is showing neighboring information properly. I asked the customer to share the wireshark information to analyse where CDP traffic is dropping
Userlevel 3
Hi,
In addition to the post, I am trying to configure cisco ip phone detection using CEP auth to split voip data and pc data.
We are trying this because you can do this using Policy Manager and dont need to configure ciscodp using cli in the device.
At the moment, when the voip phone is detected by cep (with ciscodp cep option and policy) the phone works correctly using the vlan configure in the policy but also the pc is configured automatically in the voip vlan...
Somebody have CEP authentication working witch voip phone and pc?

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