DHCPINFORM subnet selection

[Bruce Hudson]

    I sent this issue to the users list but got no reply. Perhaps this is
a more appropriate venue.

    We are seeing new Vista systems broadcast a DHCPINFORM after they get
their IP address from the DHCP server. When processing this request, the
DHCP server is using the relay IP address to determine the subnet, rather
than using the actual IP address of the client. 

        /* Find the subnet that the client is on. */
        if (gip.len) {
            /* XXX - do subnet selection relay agent suboption here */
            find_subnet(&subnet, gip, MDL);
        } else {
            /* XXX - do subnet selection (not relay agent) option here */
            find_subnet(&subnet, cip, MDL);
        }

    In a lot of shared-subnet situations, this is almost certain to give the
wrong information to the client. 

    Does anyone know WHY the relay address is used or if changing the code
to simply use the client address will cause any other issues?
--
Bruce A. Hudson				| Bruce.Hudson at Dal.CA
UCIS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405