5610 VPN phones don't always pick up dhcp ip addr

[tektekkie]

I have 3 5610SW phones configured as VPN phones.
The phones connect & work perfectly fine when tested at some locations but at other locations they fail to get an ip address from the dhcp server. Being a vpn phone the dhcp server is always the broadband/adsl router at the user's home. Yet a pc connected to the same router will receive an ip address no problem.
When configured with static ip settings, the phone returns "Bad router" even though the static settings are definitely correct.
This problem has occured on 3 different broadband routers and after looking more in depth at a network sniffer trace I can see that the phones do request an ip address but receive no dhcp offer or any response whatsoever from the router.
Questions:
Has anyone else come accross this bizarre fault before and managed to suss it?
Is it possible that the parameters requested during the dhcp request are too complex for the simple dhcp server on the adsl router to respond to?

Any help on this would be appreciated.

 

[IPOfficeIreland]

why wouldn't you just set them as static, you already have the ipo address programmed and fileserver. I did see this on dynamic sites, where being dynamic the internet connection resets itself every 24 hours to renew the address.

If you had a static address on the TSP you wouldn't get this issue, but to get round it, just make the phone static.

 

[tektekkie]

My client needs to be able to send the phones to remote destinations where the users are not very pc literate and so an easier deployment when the phone uses dhcp.

The problem as stated before is that when the phone is used on a router with the dhcp issue it also comes up with the error "Bad router" when configured with static addressing.

Thanks for the info about the internet connection re-issuing its ip address every 24 hrs - that sorts another unrelated problem of mine.

 

[IPOfficeIreland]

no problem, makes vpns a nightmare, even with dynamic name crap.

what version are the ip phones running?
the fault is basically too many bad packets so that the ip phone assumes connection is dead, you could be getting into bad quality network/wan issues here.

 

[tektekkie]

The phone doesn't even get to the point where it attempts vpn connection. The problem happens right at the begining when the phone is booted and looks for an ip address, it just sits and waits endlessly for an address but a pc on the same network picks up an address straight away.

 

[IPOfficeIreland]

try changing your file server address to dhcp client

 

[tektekkie]

The problem was the phone had 802.1Q tagging set to ON. The client's adsl router did not support QoS so did not recognise the data packets. When 802.1Q is turned OFF on the phone it booted and connected fine.
It seems that adsl routers that do not support qos will not pass or even recognise the packets if they have 802.1Q tagging.