Digi WAN 3G User Manual page 60

DHCP server settings
The DHCP server feature can be enabled in a Digi device to allow other devices or hosts on this
network to be assigned dynamic IP addresses. This DHCP server supports a single subnetwork
scope.
For the DHCP server to operate, the Digi device must be configured to use a static IP address. For
information on how to configure static IP settings, see "Ethernet IP settings" on page 55.
DHCP terminology
Some key DHCP terms involved in configuring a DHCP server include:
scope
A scope is the full consecutive range of possible IP addresses for a network. A scope typically
defines a single physical subnet on your network, to which DHCP services are offered. A scope
is the primary way for the DHCP server to manage distribution and assignment of IP addresses
and related configuration parameters to its clients on the network.
exclusion range
An exclusion range is a limited sequence of IP addresses within a scope, excluded from DHCP
service offerings. Exclusion ranges assure that any addresses in these ranges are not offered by
the server to DHCP clients on your network.
address pool
After the scope is defined and exclusion ranges are applied, the remaining addresses form the
available address pool within the scope. The addresses in this pool are available for dynamic
assignment by the server to DHCP clients on your network.
lease
A lease is the length of time that the DHCP server specifies, during which a client host can use
an assigned IP address. When the DHCP server grants a lease to a client, the lease is active.
Before the lease expires, the client typically needs to renew its address lease assignment with the
DHCP server. A lease becomes inactive when it expires or it is deleted at the server, or if the
client actively releases the lease. The duration of a lease determines when it will expire and how
often the client needs to renew it with the DHCP server in order to retain the lease.
A DHCP server will never grant a lease to its own address. There is no need for its own address
to be in the exclusion range; the DHCP server simply protects its address from being offered.
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