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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)

Cases Where Manual Configuration Is Not Feasible

The drudge work associated with manual configuration is significant, but the problems with manual configuration go well beyond the inefficiency issue. There are situations where manual configuration is not just inconvenient, it's actually impossible:

• Remote Configuration: An administrator cannot be everywhere; modern networks can span cities or nations. Unless we want to train every user on how to configure network hosts, we must use an automated protocol.
  
  
• Mobile Device Configuration: IP was designed when computers were large and attached to each other using heavy cables; today we have computers that fit in a shirt pocket and communicate using radio waves. IP addresses must be assigned based on the network to which they are attached, and this makes reconfiguration required when a device is moved. This is not conducive to manual configuration at all.
  
  
• “Dumb” Host Configuration: Most of the hosts we use today are full-fledged computers, with their own internal storage. We can assign such a device an address by entering it into a file that the device reads when it starts up. There are certain devices, however, that do not include any form of storage. Since they are mass-produced, they are all identical and cannot have individualized parameters stored within them. Such a device relies on a configuration protocol to learn what it needs to function on a network—especially including its individual identity, as we saw above.
  
  
• Address Sharing: The proliferation of devices attached to the global Internet has led to a situation where IP addresses must be carefully managed to ensure that they are not wasted on devices that aren't using them. Some organizations even find themselves with more potential hosts than they have addresses. A host configuration protocol can allow an address to be automatically assigned to a host when needed, and then returned to a common “pool” for reuse when the host leaves the network. This permits addresses to be shared and reduces the need for more address space.

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