Netopia 4000-Series manual Dhcp Relay Agent

6-30 Firmware User Guide

DHCP Relay Agent

The Netopia Firmware Version 5.4 offers DHCP Relay Agent functionality, as defined in RFC1542. A DHCP relay agent is a computer system or a router that is configured to forward DHCP requests from clients on the LAN to a remote DHCP server, and to pass the replies back to the requesting client systems.

When a DHCP client starts up, it has no IP address, nor does it know the IP address of a DHCP server. Therefore, it uses an IP broadcast to communicate with one or more DHCP servers. These broadcasts are normally limited to the network segment on which the client is located, and do not pass through routers such as the Netopia Router. If the Netopia Router is configured to act as a DHCP server, it will assign the client an address from an address pool configured locally in the Netopia Router and respond to the client's request itself.

However, if the Netopia Router is configured to act as a DHCP relay agent, it does not satisfy the DHCP request itself, but instead forwards the request to one or more remote DHCP servers. These servers process the request, assign an address from an address pool configured on the remote server, and forward the response back to the Netopia Router for delivery back to the client. The agent then sends the response to the client on behalf of the DHCP server. This process is transparent to the client, which doesn't know that it is communicating through an intermediary rather than directly to a local server. Using DHCP relay, it is possible to centralize the configuration information for the host computers at many remote sites at a single location, easing the burden of administering configuration management for remote sites.

To configure the Netopia Router to act as a DHCP relay agent, from the Main Menu navigate to the System Configuration menu.

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