Lancom Systems LCOS 3.50 - Manual (Page 274)

LANCOM Reference Manual LCOS 3.50 ̈ Chapter 13: Server services for the LAN
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13.1.3 How are the addresses assigned?
IP address assignment
Before the DHCP server can assign IP addresses to the computers in the net-
work, it first needs to know which addresses are available for assignment.
Three options exist for determining the available selection of addresses:
̈ The IP address can be taken from the address pool selected (start address
pool to end address pool). Any valid addresses in the local network can
be entered here.
̈ If '0.0.0.0' is entered instead, the DHCP server automatically determines
the particular addresses (start or end) from the IP or intranet address set-
tings in the 'TCP-IP-module' using the following procedure:
୴ If only the Intranet address or only the DMZ address is entered, the
start or end of the pool is determined by means of the associated net-
work mask.
୴ If both addresses have been specified, the Intranet address has prior-
ity for determining the pool.
From the address used (Intranet or DMZ address) and the associated net-
work mask, the DHCP server determines the first and last possible IP
address in the local network as a start or end address for the address pool.
̈ If the router has neither an Intranet address nor an DMZ address, the
device has gone into a special operating mode. It then uses the IP address
'172.23.56.254' for itself and the address pool '172.23.56.x' for the
assignment of IP addresses in the network.
If only one computer in the network is started up that is requesting an IP
address via DHCP with its network settings, a device with an activated DHCP
module will offer this computer an address assignment. A valid address is
taken from the pool as an IP address. If the computer was assigned an IP
address at some point in the past, it requests this same address and the DHCP
server attempts to reassign it this address if it has not already been assigned
to another computer.
The DHCP server also checks whether the address selected is still available in
the local network. As soon as the uniqueness of an address has been estab-
lished, the requesting computer is assigned the address found.
Netmask assignment
The network mask is assigned in the same way as the address. If a network
mask is entered in the DHCP module, this mask is used for the assignment.