DHCP helper - to windows server, not working

[philippe.cousineau]

Hi there,

I have a pretty weird issue here.

I have a layer 3 switch, if the dhcp is configure on it my phones are getting an IP and everything is fine.

As soon as I configure a dhcp helper on it, phones doesnt get an IP anymore.

The helper point to a windows server that have the right scope configure on it and enable...

We did'nt configure anything special reliated to the vlan, but just the right scope that match the subnet where the dhcp request was made and it doesnt work. ( Only thing specific is the option 150 that we configure on the server to inform the phones where to get their config. files )

from the layer 3 switch we can ping the Windows dhcp server but... doesnt work.

anyone have an idea? is there another specific thing to configure on the Win Server.. ?

[ajay chauhan]

Did  you check if any ACL in between?

[philippe.cousineau]

There is no ACL,

I will also double-check if all ports are configure as dhcp trusted ports

other suggestion ?

[cadet alain]

Hi,

is the server configured with a route for the remote subnet it is leasing addresses to?

Can you ping it from a machine with a static IP in this subnet?

Regards.

Alain

[internodetech]

Is the server getting the DHCP request packets? I would run a packet sniffer  on the server or SPAN  it's port to a sniffer like wireshark to see it that's the case. My experience is with ISC dhcpd and it logs every request that comes in. I'm not sure if Windows has a similiar logging/debugging option.