IP Helper Configuration

Unanswered Question
Aug 16th, 2007


Regarding IP-Helper Configuration, when you list IP addresses with the ip-helper address command, does the router forward the broadcast/DHCP/BootP request to the first IP address on the list first or does the router forward the request to all IP addresses on the list?

Just wondering....

I have this problem too.
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Richard Burts Thu, 08/16/2007 - 13:31


When you configure multiple ip helper-address statements, the router will forward broadcasts to each of the addresses in the list.



royalblues Fri, 08/17/2007 - 01:21

As rick said, the broadcast is forwarded to all the addresses in the list.

Each DHCP server send a response to the host.

The Host then chooses a DHCP server and requests for the IP address



Pavel Bykov Fri, 08/17/2007 - 08:52

Additionally to Rick an Narayan, in practice VLANs are setup with several helper-addresses (2 or 3 in our case) and then only one one of the destination DHCP servers the SCOPE is enabled (it's disabled on other servers). in case of server failure with an active SCOPE, this SCOPE on another server is activated.

hermanaccd Fri, 08/17/2007 - 09:08

Thank you everyone for your answers and feedback - Greatly appreciate it!


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