set provisioning tftp server in dhcp answer with use vendor-id

[olegk]

Hello.

We use different tftp servers for different purposes. And in dhcp (MS dhcp server) in option 66 we set one tftp server, but for phones we need set another tftp server. We tryed use vendor-id (option 60) in dhcp server, define vendor class and option 66 for this class. Now in reply to yealink dhcp request server send answer with option 43, in which encapsulated option 66 with address of tftp server. But phone ignored it and don't use this server. If we set address of tftp server directly in option 43 (not in encapsulated to option 43 option 66) - this worked and phone used this tftp server.

How we can set right tftp server for yealink phones, based on option 60 in dhcp request and other tftp server for all other devices without option 60?