M and MSM Series

MSM 720 with external DHCP server

Piero Bacarella
Occasional Contributor

MSM 720 with external DHCP server

Hi everyone,
I've 2 MSM 720 in teaming mode (connected directly on ports 1 of each controller with an ethernet cable).

On ports 1-2-3-4 (Access Network I've some HP 425 APs connected directly to these ports.

On port 5 I've connected a switch untagged port that brings users to Internet (Internet network

If I use non-teaming mode, controller's DHCP server gives correctly the IP addresses to users and APs, and users can reach Internet.

But in teaming mode I have to use an external DHCP server. The DHCP service is running on a layer 3 switch (HP A5500) that provide the
Internet network via port 5. I configured the DHCP relay agent as you can see on the screenshot.

I want to give to my users and to APs the IP addresses of the Access network (, but the DHCP server is located on the Internet
network (
In the DHCP server pool I also configured the Option 43 as following:

dhcp server ip-pool hp-wlan
network mask
domain-name elis.org
expired day 0 hour 9
option 43 hex 0108 0ABEBE02 0ABEBE03

where 0ABEBE02 0ABEBE03 are and (the IP addresses of the teamed controller on Access Network).


So, when I connect the APs on the Access Network ports the APs don't get any IP address, so red led blinks and no APs are discovered on

Where is the mistake?

Many thanks to all!


Regular Visitor

Re: MSM 720 with external DHCP server

Helo Piero,

if i read your post correctly so resides your DHCP Server on the Internet Network of MSM720. You can read about DHCP Relay in the Config Guide:


NOTE: • DHCP relay is not supported on the Internet port when it is operating as a PPPoE client or if the firewall is set to High and NAT is enabled. This is because DHCP server must be able to ping the assigned address to prevent duplicate assignments.


May be is that your mistake