School of Medicine

Most telephones will work immediately if plugged into an active telephone socket. This is because a telephone handset is not set to work only with one particular telephone number or with one local telephone exchange. Computers are different. Each computer needs to have its own IP address set before it can talk on the network. It also needs to be set with the address of its local network gateway, and various other information. These settings are only locally appropriate - a computer from DMC can't successfully be plugged into a network socket in Scott Hall.

No two computers on the Internet are allowed to have the same IP address. If two are given the same address by mistake, one or both will not work. Managing the allocation of IP addresses is an important administrative duty. There is a limited supply of them, so they must be reclaimed from decommissioned computers so the addresses can be recycled. It is thus very important to know what network settings each computer has been given.

Traditionally, network settings were entered by hand into computers. If they needed to be updated, changes were also made by hand. It was also not possible to find out a computer's settings without going to the machine to look. This scheme worked best when computers were kept together in dedicated computer rooms.

Now that so many offices contain a computer, it is no longer practical to keep their network configurations up to date by hand. Fortunately, most computers can now use "Dynamic Host Configuration Protocol" ("DHCP"). A computer using DHCP does not store a permanent network configuration. When it is turned on, it sends a special message out its network port. A configuration will be sent to it by a DHCP server listening on the network.  This configuration info includes an IP address for it to use, as well as sets the computers gateway and  net mask addresses.  It also tells the computer what WINS and DNS servers it should be using.

DHCP thus allows network administrators to keep all of the configuration for the computers together in the one place. This greatly reduces the chance of mistakes and keeps a clear record of the addresses which are currently in use. No-one needs to unlock individual offices to make an update to a computer's network configuration.   An if a computer is removed from the network, after 7 days of not contacting the DHCP server, the IP address is automatically re-added into the IP address pool for someone else to use.

The MSIS runs a DHCP server which currently services all of Scott Hall but as the network is flattened, it will be able to service other buildings.  The list of buildings that still need to be moved to DHCP are parts of UHC,  Lande, Elliman, Alexandrine (hen the fiber is in) KEI, parts of Harper Professional and Hutzel, Karamanos, Brush, parts of Detroit Receiving and the VA.