Dynamic Host Configuration Protocol (DHCP)
DHCP is a protocol used by most modern home network routers, network providers and ISPs to automatically assign, on demand, an IP address to a host that wishes to connect to an intranet or the Internet. In the context of home (and some institutional) networks, DHCP allocates addresses from a pool of private IP addresses (e.g. 192.168.1.100). Such hosts cannot directly connect to the Internet and need to connect instead through what is called a NAT service. In larger ISPs such as swan.ac.uk or your broadband supplier, IP addresses are allocated via DHCP from a pool of IP addresses that the ISP has purchased from a higher level ISP. Thus when connecting your registered lap top to the University via the wired Ethernet, you will be assigned an IP address that starts 137.44. However, when you connect via WiFi, you will be allocated a private IP address that starts 192.168 and your messages will be routed to the Internet via a NAT server inside the wireless router.
DHCP can be set up to only grant an IP address assignment request from network interface cards with a known physical (MAC) address. This is why you have to register your laptop with the University before it can be connected to the wired or wireless service.
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