Chapter 20: Dhcp Configuration; Dhcp Overview; Configuring Dhcp - Enterasys Matrix DFE-Gold Series Configuration Manual

This chapter describes the Dynamic Host Configuration Protocol (DHCP) configuration set of
commands and how to use them.

DHCP Overview

The Dynamic Host Configuration Protocol (DHCP) provides services for allocating and delivering
IP addresses and other configuration parameters to Internet hosts. DHCP consists of two
components: a protocol for delivering host‐specific configuration parameters from a DHCP server
to a host, and a mechanism for allocating network addresses to hosts. Optional functionality also
provides services to complete high‐availability, authenticated and QoS‐dependant host
configuration.
The DHCP protocol is based on a client‐server model in which a designated DHCP server
allocates network addresses and delivers configuration parameters to dynamically configured
clients. Throughout the remainder of this section, the term "server" refers to a host providing
initialization parameters through DHCP, and the term "client" refers to a host requesting
initialization parameters from a DHCP server.
DHCP supports the following mechanisms for IP address allocation:
• Automatic — DHCP assigns an IP address to a client for a limited period of time (or until the
client explicitly relinquishes the address).
• Manual — A clientʹs IP address is assigned by the network administrator, and DHCP is used
simply to convey the assigned address to the client.
The amount of time that a particular IP address is valid for a system is called a lease. The
Enterasys Matrix‐N or standalone device maintains a lease database which contains information
about each assigned IP address, the MAC address to which it is assigned, the lease expiration, and
whether the address assignment is dynamic or static. The DHCP lease database is stored in flash
memory.

Configuring DHCP

By default, the DHCP server is not enabled on the Enterasys Matrix‐N or standalone device. You
can selectively enable DHCP service on particular interfaces and not others. To enable DHCP
service on an interface, you must first define a DHCP scope. A scope consists of a pool of IP
addresses and a set of parameters for a DHCP client. The parameters are used by the client to
configure its network environment, for example, the default gateway and DNS domain name.
Router: Unless otherwise noted, the commands covered in this chapter can be executed only
when the device is in router mode. For details on how to enable router configuration modes, refer to
"Enabling Router Configuration
DHCP Configuration
Modes" on page 2-103.
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