All devices in a local area network require a unique IP address in order for a TCP/IP network to function smoothly. They also require the addresses of DNS servers and also of a standard gateway that can route data packets to addresses not located on the local network.
In a small network it is still possible to enter these addresses on all the computers in the network manually. However, in a large network with many workstations this soon becomes an unmanageable task. This is where the use of DHCP (dynamic host configuration protocol) comes in. A DHCP server in a TCP/IP-based LAN can use this protocol to assign the required addresses to the individual workstations dynamically.
The devices have an integrated DHCP server that can assume the task of assigning IP addresses. This process involves communicating the following parameters to the workstations:
- IP address
- Netmask
- Broadcast address
- Default gateway
- DNS server
- NBNS server
- Lease (validity period) of the assigned parameters
The DHCP server must first know which IP addresses it can use to assign before it can actually assign them to workstations in the network There are three different methods for selecting possible addresses:
- An IP address can be taken from the defined address pool (Start address pool to End address pool). Any address can be entered provided it is valid for the IP network segment.
- If "0.0.0.0" is entered, the DHCP server determines the relevant first and last addresses itself using the settings for the IP network (network address and netmask).
- The device will be in a special operating mode if no IP network has yet been defined. It then uses the IP address "172.23.56.254" and the address pool "172.23.56.x" for assigning IP addresses to the network.
When a client is activated in the network and requests an IP address via DHCP, the device with an activated DHCP server will offer to assign an address. This address is selected from the pool of valid IP addresses. A computer which received an IP address in the past requests this address again and, assuming the DHCP server has not assigned this number to another computer in the meantime, it will attempt to issue this address again.
The DHCP server also checks the LAN to confirm that the selected address is free. Once the address is confirmed as unique, it is assigned to the requesting computer.
Therefore in the most basic scenario you only need to connect a new out-of-the-box device to a network without a DHCP server and switch it on. The DHCP server will then manage all further address assignment in the LAN by itself in cooperation with LANconfig using a Wizard.
