DHCP helper

[Ceaserx]

Hi

I would like to run a config past you guys.

I need to configure a network using 4 Vlans. Vlan 1 = Management, Vlan 2 = Servers, Vlan 3 = Users 1st floor, Vlan 4 = Users Ground floor

We are using a 5406 as the core and 16 x 2520's on the edge. Will it work fine if I add a DHCP helper address on the 5406 on each of the Vlans(except vlan1) to get an address within that Vlan's subnet? The 2520's don't have the dhcp helper option available. The default gateway of each edge switch is the core switch.

They use a windows DHCP server with a superscope that contain the 3 different subnets.

The dhcp server sits in the server vlan. Will this work fine?

 

[cajuntank]

Sure will. Just add the ip helper-address "IP address of DHCP server" (minus the quotes) and as long as you have those scopes for those subnets defined on the DHCP server that match the network IP subnet you have defined on each of your VLAN interfaces to route, then your golden.
So for example.

VLAN 1
ip address 192.168.1.0 255.255.255.0
exit

VLAN 2
ip address 192.168.2.0 255.255.255.0
ip helper-adress 192.168.1.10
exit

ip routing

192.168.1.10 being what your DHCP server address would be in this example and ip routing statement needed so layer 3 interfaces can route between each other (VLAN interfaces become layer 3 interfaces as soon as you give them an IP address)

Hope that helps.

 

[Ceaserx]

Thank you!!