IP Helper question

[rtiv]

Hello,

On our RSM router, we have multiple VLAN's set up. Each config has a single ip helper statement pointing to our primary dhcp server. I just built a redundant one and was wondering if it is possible to put a 2nd ip helper statement in the config? Will this work ?

Thanks

 

[svermill]

Yes. You can name as many helper addresses as you like. All requests get sent to all helpers, so you just need to be aware of that. But two certainly is within reason.

 

[svermill]

Also remember that you can name the entire subnet and just get one broadcast if both machines are in fact on the same subnet.

 

[rtiv]

Actually, both are on the same subnet. What would the command be ? I'm actually new to Router administration...if I do a "show run", I can see all the VLAN's defined and each one has the single IP helper statement. What commands do I need to go in and add the additional helper address ? or the single address your referring to ?

Thanks again

 

[svermill]

Just add another 'ip helper-address' command followed by the IP of your new server. Or determine the broadcast address (e.g. .255) of the subnet on which the servers reside and use that in your 'ip helper-address' command. Then you can remove the old one with the the 'no' form and the IP of the original server. If you direct to the broadcast, I think you have to now add 'ip directed-broadcast' to the ethernet interface where the servers are. Let us know if you have any trouble.