Understanding dhcrelay

[Kay Wanous]

Hello,

I'm trying to set up dhcrelay but based on what I'm reading I think I'm 
either missing a critical step or I don't understand how it works.

The dhcrelay server receives a DHCP request on its internal interface 
(192.168.0.1) and places that IP address in the giaddr field, then sends 
it from its outside interface (routable IP) to the dhcp server (routable 
IP).  The dhcp server sees the giaddr and instead of replying to the 
routable IP of the dhcrelay server, it responds to 192.168.0.1.  But 
since the dhcp server can't reach the internal network, the response is 
never received on the dhcrelay server.

Since the dhcp server can't get to the internal network (isn't that the 
whole idea of dhcrelay?), if it's answering to the giaddr field, how 
would the response ever get back to the dhcrelay server so that it could 
get back to the requesting client?

Any help in clearing up this confusion is greatly appreciated.

Thanks,
Kay