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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)            9  Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP)

Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP) 1 2 3 TCP/IP Bootstrap Protocol (BOOTP)

Putting a host on an internetwork requires that certain setup and configuration procedures be followed. Hardware must be selected and set up, and software too must be chosen and installed on the hardware. Once the software is set up, we aren't finished, however: we must also perform other configuration tasks that tell the software how we want it to operate, and give it certain parameters so it knows its role on the network and how to function.

Probably the most important configuration task that must be performed for each host on an internetwork is to give it an identity, in the form of an address that is unique to it alone. In TCP/IP networks, each device must be given an IP address. Hosts also often require other parameters to ensure that they operate properly. For a TCP/IP network, we might want to tell each host some of the following:

• The address of a default router on the local network.
  
  
• The network mask the host should use.
  
  
• The addresses of servers providing particular services to the host, such as a mail server or a DNS name server.
  
  
• The maximum transmission unit (MTU) of the local network.
  
  
• What Time To Live (TTL) value to use for IP datagrams.

And possibly, a lot more; there are dozens of different parameters that must be set up for certain networks. Many of these may be common to all the machines on a network, but IP addresses must be unique. The administrator must therefore ensure that each is assigned to only one computer, even as machines are added to and removed from the network.

If you're an administrator in charge of a small ten-host LAN, performing setup and configuration is simple: for each host, you set up the hardware, install the software, and then configure the software. Even changes and keeping track of IP addresses wouldn't be a big deal; a single sheet of paper would suffice. However, what happens when your network has not ten computers but a hundred? How about a thousand? Ten thousand?

As the size of the network grows, the work needed for manual configuration grows with it. And while initial hardware setup may be time-consuming, at least it is done mainly when the host is first set up, and rarely changed thereafter. This is not the case with configuration parameters. If the address of the local router changes on a network with a thousand hosts, do you really want to go to each host to edit a configuration file? I sure don't!

Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP) 1 2 3 TCP/IP Bootstrap Protocol (BOOTP)