ip helper address help

[karthikeyan gopinathan]

Hi

i created a new vlan and added a ip helper-address command. the ip in the helper-address will be my primary dhcp server, but i have my secondary dhcp server how do i add this in the configuration give another ip helper-address to the vlan and how do i mention that one is primary and another is secondary

interface Vlan205
  ip address 172.25.5.1 255.255.255.0
ip helper-address 172.25.1.5
end

the idea is one dhcp server goes down it has to go to the other dhcp server

please let me know you suggestions

[John Blakley · Accepted solution]

You just add another line. You can't define primary or secondary. It's just going to take whichever responds first.

HTH,

John

[Jon Marshall · Accepted solution]

Just to expand on John's answer. You don't have a primary and secondary, they are both used. So you need to make sure that each DHCP server is not handing out the same addresses eg.

192.168.5.0/24 subnet. You would split this between the 2 DHCP servers by splitting it in half eg.

192.168.5.0/25 on DHCP server 1

192.168.5.128/25 on DHCP server 2

Whichever DHCP responds first is generally the one used which is not an issue if you split the scopes correctly.

Jon