2.9 Host Configuration


Internet hosts need to be configured with certain information that allows applications to operate and packets to be routed. Information that is most commonly configured includes the IP address, the gateway, and the DNS server. Configuration can be done manually or can be via an automated process. Manual configuration requires the user to be networking savvy to some extent. The Dynamic Host Configuration Protocol (DHCP) provides configuration parameters to Internet hosts . DHCP is specified in RFC 2131. DHCP is an application-layer protocol that follows the client/server mode. From the client perspective, it can be viewed as an extension to BOOTP, which is used to bootstrap hosts. One thing to note about DHCP is that it is for confguring hosts only and is not intended for routers.

There are primarily two components to DHCP: a client piece of software and a DHCP server. After obtaining parameters via DHCP, a DHCP client should be able to exchange packets with any other host in the Internet. The main services provided by DHCP are to provide persistent storage of network parameters for network clients and to allocate temporary or permanent network (IP) addresses to clients . IP address allocation in DHCP has three mechanisms:

  • Automatic ” A permanent IP address is assigned to the client.

  • Dynamic ” An IP address is allocated to the client with a lifetime associated with it.

  • Manual ” The IP address is assigned by the operator and DHCP is simply the carrier of this information.

Other extensions to DHCP include the concept of a relay agent that can forward DHCP messages to a server that is located elsewhere in the network. Clients broadcast a DHCPDISCOVER message on the local physical subnet and servers on the network respond with a DHCPOFFER message. The client selects one of the offers and sends a DHCPREQUEST message to the server that made the offer. The server responds with a DHCPACK, and initialization is complete.



IP in Wireless Networks
IP in Wireless Networks
ISBN: 0130666483
EAN: 2147483647
Year: 2003
Pages: 164

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