We have a perimeter router. The perimeter router has connections to the Internet, VPN clients, two point-point connections to branch offices and the LAN. The LAN is one network-one IP scheme. We would like to segregate the LAN/network to minimize collision and for enhancing security. Our Cisco switch can be configured for VLANs. How do the VLANs get dynamic IP addresses?
Win 2003 server is capable of assigning dynamic IPs for multiple subnets. You would configure multiple scopes on the Win 2003 DHCP server (one scope per subnet).
There are choices about how to implement DHCP. Some people configure the DHCP service on one (or more) of their routers. Some people implement DHCP on separate servers, one server per subnet. Most people implement a single server with multiple scopes.
You are correct that by default broadcasts are limited to the individual subnet. To get the DHCP request broadcast from the local subnet to the remote server you can configure the ip helper-address command which will look for DHCP broadcast requests (as well as a few other kinds of broadcasts) and will forward a copy of the request to the remote DHCP server.