Wireless Access

Occasional Contributor II

dhcp relay

i have a question about the dhcp relay..because my box is on delivery,so i can't test now..hope someone give me ideas...many thanks...

my design breif is below:
user subnet
controller ip
gateway(core switch )

i want the controller does a dhcp relay agent..but the user gateway is point to the core switch...
between user and controller is tunnel mode ...
so i just need to configure the uplink of controller to be a trunk,right ?

and one more question, can i see user information like mac address on controller ? any command to do that ?

many thanks for all reply

Re: dhcp relay

Yes you can see mac address information on your controller



About the Dhcp Relay.


Okay if you got your Interface vlans on your core switch, which it should be like that.

Then the DHCP relay or Ip helper should be configured in the Switch core  NOT on the wireless controller.


You will want to do a L2 controller deployment, ill give you an example of how is it


WLAN VLan 2 =

WLAN Vlan 3  =

Equipment vlans(like the vlan in which you got your switches and that kind of stuff) in which you can put your Wireless controller

Example Vlan 5 =


Ip address of your Wireless controller =

ip address of that vlan on the switch core =

Default gateway of your Wireless controller =


You need to trunk to the controller vlan 2,3,5



An L2 deployment consist in trunking vlans to the wireless controller

There is also a L3 deploying which consist on managing routes between the swtich core and the Wireless controller but the L2 deployment is recommended.


In the example i gave you the default gateway of your WLAN users is the Switch Core

You would have on your switch core an interface vlan for vlan 2 and vlan 5


All the routing is done on the switch core.


I dont know if this help you with your question??? or you got something you would like to ask?




Product Manager - Aruba Networks
Alternetworks Corp
Occasional Contributor II

Re: dhcp relay

firstly, thanks for help..my core switch cannot be a dhcp agent with some non technical problem...

so there is no way to make dhcp agent on controller but the gateway is on the core switch,right ?

Re: dhcp relay

Why you cannot put the ip helper on the switch core???

Product Manager - Aruba Networks
Alternetworks Corp
Occasional Contributor II

Re: dhcp relay

business issues....hard to explain

so there is no way to do that unless i put the dhcp agent on core switch in my criteria,right ?
Valued Contributor I

Re: dhcp relay

You should be able to use the controller as the IP helper/relay, and the core as the gateway yes.


The controller will use it's address as the relay source, and it will send the requests to whatever your DHCP server is.


In the DHCP server scope, define the default router as the core switch IP.


As long as the DHCP server can route back to that user network (via the core I would imagine), it should be fine.


Granted, it's a much cleaner/simpler setup if the default router and helper is the same device, but it's not mandatory.




Kudos appreciated, but I'm not hunting! (ACMX 104)
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