DHCP relay

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Alternate configuration

If the DHCP client subnet includes a BIG-IP system that serves as a hop to the BIG-IP relay agent, you must perform two additional configuration tasks:

You must configure the BIG-IP relay agent to relay the client DHCP requests to the DHCP servers without losing the originating subnet (source) IP address. This originating source IP address is typically a self IP address of the BIG-IP system that resides on the client subnet. You configure the BIG-IP relay agent to preserve the originating source IP address by creating a SNAT that specifies the originating self IP address as both the origin address and the translation address. A SNAT configured in this way prevents the BIG-IP relay agent, before sending the DHCP broadcast message to the DHCP servers, from translating the source IP address of the incoming DHCP request to a different address.
You must add a route (to the BIG-IP relay agent) that specifies the originating source IP address as the destination for DHCP responses. The DHCP servers use this route to send their responses back through the BIG-IP relay agent to the clients.