This is a follow up post to an earlier post on LLDP-MED. VoIP phones on the market today follow the same basic boot and operations process:
1 – Wait for an LLDP packet from the Ethernet switch
2- Send a DHCP discovery packet to find the DHCP Server
3- Send a DHCP request to the DHCP server to get an IP address
4- Send an LLDP-MED packet to the Ethernet switch
5- Wait for an LLDP-MED packet from the Ethernet switch and read the Network Policy TLV to get the VLAN ID, L2 priority and DSCP value
6 – Download applciations and software from the “call manager”
7 – After configuration , voice packets are sent as tagged frames and data packets are sent as untagged frames
The ShoreTel implementation of LLDP seems to follow this process only after step 5, the result of the IP Phone learning LLDP by having its firmware configured. In other words, a phone out of the box is a hung of iron with no inherent ability to define itself as an IP phone to an LLDP enabled ethernet switch. The ShoreTel phone will still require an intial boot in the native VLAN and then reboot in the voice vlan, where it will then download its firmware. The real value here, is that once this process is “learned” by the ShoreTel phone, should the phone restart for any reason in the future, it can start at step one above. LLDP in ShoreTel is a version 9.1 feature enhancement not available in earlier releases of ShoreTel.
update 2/15 see article at Support.DrVoIP.com