DHCP Relay Agent

A DHCP Relay Agent should be configured on you RRAS server if you wish for remote access clients to obtain complete IP settings via DHCP. If you choose to have clients obtain settings from DHCP without setting up a Relay Agent, then the client will only obtain an IP address and subnet mask from the server, regardless of which options may exist. The traditional use of a DHCP Relay Agent was to act similar to a BOOTP Forwarder, a system that allows DHCP broadcasts to be directed to a DHCP server that may exist on another subnet. If DHCP Relay Agents (or equivalent) are not used, then a DHCP server must exist on the same subnet as the client, which may not be practical.

In RRAS, a DHCP Relay Agent is configured under the IP Routing section. By accessing the DHCP Relay Agent properties, you can configure to which servers DHCP requests will be forwarded by this agent.

Note also that by double-clicking on any interfaces in the DHCP Relay Agent interfaces, you can configure both the Hop-count Threshold (which controls the maximum number of relay agents that will handles a request), as well as the Boot Threshold (the number of seconds that the relay agent will wait prior to relaying requests) for the agent. The default value in both cases is 4.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of 2000Trainers.com. He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.