dhcp for Cisco voip phone

[carl_townshend]

Hi

I know that when the Cisco phoen gets the voip vlan it gets it using CDP from the switch, if the switch doesnt use CDP then how can the phone get the voip vlan, I know you can do it manually but can you get the phone to learn its vlan via DHCP option ?

cheers

[kcnajaf]

Hi Carl,

Unfortunatly as far as i know you can not let the phone know about voice vlan through DHCP.

If you look at the packet format of a DHCP request there is no field on them to carry the VLAN informations. Please refere to the link below for DHCP packet format.

http://www.tarunz.org/~vassilii/TAU/protocols/dhcp/frame.htm

Hope that helps.

Regards

Najaf

Please rate when applicable or helpful !!!

[Abzal]

Hi,

For VoIP phones you need to use either CDP or LLDP.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_55_se/configuration/guide/swvoip.html

https://learningnetwork.cisco.com/thread/47477

Hope it will help.

[cadet alain]

Hi,

it is possible for some non Cisco IP phones with option 43 but not with Cisco phones as far as i know.

Regards.

Alain