03-03-2013 03:55 PM - edited 03-21-2019 07:02 AM
Hello,
Do you know which methods the IP Phones use to get configured in order to work on a particular Vlan? (For example via CDP protocol)
And also if the phone receives VLAN settings from multiple methods, then which is the priority that the phone follows?
Thank you in advanced for your help
03-03-2013 04:01 PM
Hi Christos, CDP or LLDP-MED. I personally don't know if there is a "priority" but I would also say it is fair enough you shouldn't be running LLDP-MED network policy inconjunction with a CDP voice policy.
If you have phones that don't support CDP you should be using LLDP-MED if the 3rd party vendor phones support it.
-Tom
Please mark answered for helpful posts
03-03-2013 04:53 PM
Hi Tom, thanks for your quick answer. As far as I know you can also set manually a static VLAN to the phone (correct me if I am wrong).
For example in case that I set manually the phone to use VLAN 50, but at the same time there is a configuration on the network device (switch) which determines the VLAN 60 as the Voice VLAN and with CDP or LLDP-MED enabled. Then which of the two VLANS will the phone use?
I believe that there should be some “priority”.
03-03-2013 04:58 PM
If you static assign the VLAN, neither cdp or lldp will tell the phone where to go since that field is occupied statically. You could also use DHCP options to have the phone be fed vlan information if you'd take it that far (back in time )
-Tom
Please mark answered for helpful posts
03-03-2013 05:25 PM
Thank you very much Tom. It just started becoming interesting with your last answer . I will look into that as well, as I want to examine every single parameter and see the phones’ behaviour.
11-06-2013 06:09 AM
Hi Tom,
do you maybe have some additional information on how to puch the vlan through DHCP. I've also got the problem that cdp or lldp isn't available.
I've tried serveral option in my DHCP server (like option 132), but so far without result.
And with all i've read so far I get the idea that the SPA5xx phones aren't able to get their vlan through dhcp.
11-06-2013 10:25 AM
It's to late to got VLAN number in DHCP response. DHCP DISCOVER/DHCP REQUEST packets needs to be sent in appropriate VLAN, so you need to know the VLAN before DHCP is started.
I assume there is no such DHCP option nor will be in the future.
11-06-2013 11:26 PM
Hi Dan,
last night I've got the idea that there is no other option for the SPA5xx phones, because if i'm not misstaken the SPA's only suppport DHCP options 66,150,159,160.
I've got the idea of this all because i've seen some cases where the customer did this on their old system.
And so I started my little search
I've have found indeed that some phones can be put in a vlan through option 43 for example.
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide