ip helper-address WAN links

[ohareka70]

Hello,

I work on a large network of about 60 sites.  I usually put on the IP helper address of the nearest domain controller on the wan interface.  Then i put another helper address for a secondary domain controller elsewhere on the network.  Is that the correct way to do this?

interface GigabitEthernet0/0
ip address 10.x.x.x 255.255.252.0
ip helper-address 10.x.x.x
ip helper-address 10.x.x.x

regards,

Kevin

[Catalin Sandu]

The ip helper-address command should be put on the interface which is receiving dhcp request messages or other way said on the interface where ip addresses you want to be assigned by a remote dhcp server.

HTH

[ohareka70]

Which domain controller should i be targetting.  The domain controller closest to the router which is on the same LAN as the router, or the primary domain controller which is 60 miles away in the Datacentre.

Around 100 users need to hit the domain controller as soon as they try and login to the network with a laptop or desktop to get onto the domain.

Kevin

[Catalin Sandu · Accepted solution]

1st. what broadcast packets and which protocols do you want to forward via ip helper-address command ?

2nd. Exemple: In case of dhcp, if dhcp server is on the same LAN with the clients you don't need to use ip helper-address because the broadcast packets will be received also by the dhcp server which will do his job.. If the dhcp server is outside the LAN with the clients than you need ip help-address command.

HTH,

Catalin

[ohareka70]

Catalin,

I think you have just answered the question. 

The Scenario is that i have a domain controller server on this particular remote LAN and this server is part of the 7 domain controllers on the network.  1 domain controller back in the Datacentre is the primary one for Active Directory in the whole estate.

So users on this remote site should pick up their dhcp from the local domain controller and only need the helper address to get to the other domain controller over the wan if the local domain controller server was offline.

thanks

Kevin