Qtech QSW-2900-24T4-AC [106/209] Brief introduction of dhcp

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Chapter 6 DHCP Configuration

6.1 Brief introduction of DHCP

DHCP messages are usually broadcast packets. So to use DHCP to allocate IP for hosts in a three-level

architectured network, there need be a DHCP server in every broadcast domain. In a three-level architectured

network constructed with QTECH QSW-3500 or QSW-3900, a DHCP server is put in each VLAN. This is a greate

waste of resources.A solution to this is to use the DHCP relay feature of QTECH QSW-2900, which relays DHCP

messages to DHCP servers.Thus only one DHCP server is needed at least.

The system support following DHCP features:

DHCP Relay;

DHCP snooping;

DHCP client.

Caution:

DHCP relay and snooping is worked only under IP managed VLAN, please see the section

Configure manage VLAN .

6.2 Introduction to DHCP

With networks getting larger in size and more complicated in structure, lack of available IP addresses becomes

the common situation the network administrators have to face, and network configuration becomes a tough task for

the network administrators. With the emerging of wireless networks and the using of laptops, the position change of

hosts and frequent change of IP addresses also require new technology. Dynamic host configuration protocol (DHCP)

is developed in this background.

DHCP adopts a client/server model, where DHCP clients send requests to DHCP servers for configuration

parameters; and the DHCP servers return the corresponding configuration information such as IP addresses to

configure IP addresses dynamically.

A typical DHCP application includes one DHCP server and multiple clients (such as PCs and laptops), as

shown in Figure 1-1.