(06-23-2014 08:25 PM)joebocop Wrote: Also, I opened a support ticket with Yealink about this problem, and they have suggested that it may be an issue with lack of sufficient power to the phones while they are booting up. We are investigating.
I would not agree to this. Think it's a matter of timing or/and specific implemetation of LLDP.
First guess, our Cisco switches do something called "Smartports", they configure the port settings dynamically on what they find by CDP or LLDP discovery protocols. It might be that the information about the voice-vlan coming from the switch is just not reaching the phones at the correct moment ...
Second, and I believe this one is actually what happens, some switches like our Ciscos send LLDP informations by more than one packet, which have to been taken into consideration by the phones LLDP implementation. The phones have to wait a little bit after the first LLDP packet received, if some more information ist coming in (remember, LLDP ist stateless). Digium agreed in the past already that they had this problem with their phone firmware. And fixed it.
Quote:1_3_3_0_55755
Issues Resolved:
The phone now accommodates certain Cisco switches and 'switchport mode trunk', a setting that could take a long time to negotiate the link with the Digium phones. This extra delay prevented the phone from acquiring LLDP-MED information.
Phone now looks at additional packets from the switch until it receives all the LLDP-MED settings. This accommodates certain Cisco switches (eg. Cisco SG500X) that do not send all the LLDP-MED policy settings on the first packet to the phone.
Phone now sends an LLDP packet with TTL of zero, to clear the cache on the switch so that it responds with the proper LLDP-MED settings.
For dhcp configuration please take a look at the two attachments for what I did:
