ELSA LANCOM Business LC-4X00, Руководство пользователя

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Operating modes and functions
ELSA LANCOM Business
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– The device then enables its own DHCP server if no other DHCP servers are found.
Whether the server is active or not can be seen in the DHCP statistics.
The default state is 'auto'.
How are the addresses assigned?
IP address assignment
Before the DHCP server can assign IP addresses to the computers in the network, it first
needs to know which addresses are available for assignment. Three options exist for
determining the available selection of addresses:
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The IP address assigned 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.
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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 settings in the
'TCP-IP-module' using the following procedure:
– If only the IP address or only the intranet address is entered, the start or end of
the pool is determined by means of the associated network mask.
– If both addresses have been specified, the intranet address has priority for
determining the pool.
From the address used (IP or intranet address) and the associated network 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.
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If the router has neither an IP address of its own nor an intranet address, the device
has gone into a special operating mode. It then uses the IP address '10.0.0.254' for
itself and the address pool '10.x.x.x' for the assignment of IP addresses in the
network. In this state, the DHCP server only assigns IP addresses and their validity
to the computers in the network, but not the other information.
If only one computer in the network is started up that is requesting an IP address via
DHCP with its network settings, a router 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 already assigned an IP address at some previous stage, 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 established, the requesting
computer is assigned the address found.