Zyxel OLT2412 [215/326] Dhcp overview

Zyxel OLT2412 [215/326] Dhcp overview
OLT2412 User’s Guide 215
CHAPTER 29
DHCP
This chapter shows you how to configure the DHCP feature.
29.1 DHCP Overview
DHCP (Dynamic Host Configuration Protocol RFC 2131 and RFC 2132) allows individual computers
to obtain TCP/IP configuration at start-up from a server. You can configure the OLT as a DHCP
server or a DHCP relay agent. When configured as a server, the OLT provides the TCP/IP
configuration for the clients. If you configure the OLT as a relay agent, then the OLT forwards DHCP
requests to DHCP server on your network. If you don’t configure the OLT as a DHCP server or relay
agent then you must have a DHCP server in the broadcast domain of the client computers or else
the client computers must be configured manually.
29.1.1 DHCP Modes
The OLT can be configured as a DHCP server or DHCP relay agent.
If you configure the OLT as a DHCP server, it will maintain the pool of IP addresses along with
subnet masks, DNS server and default gateway information and distribute them to your LAN
computers.
If there is already a DHCP server on your network, then you can configure the OLT as a DHCP
relay agent. When the OLT receives a request from a computer on your network, it contacts the
DHCP server for the necessary IP information, and then relays the assigned information back to
the computer.
29.1.2 DHCP Configuration Options
The DHCP configuration on the OLT is divided into Global and VLAN. Which you should use for
configuration depends on the DHCP services you want to offer the DHCP clients on your network.
Choose the configuration based on the following criteria:
Global - The OLT forwards all DHCP requests to the same DHCP server.
VLAN - The OLT is configured on a VLAN by VLAN basis. The OLT can be configured as a DHCP
server for one VLAN and at the same time the OLT can be configured to relay DHCP requests for
clients in another VLAN.
29.2 DHCP Relay
Configure DHCP relay on the OLT if the DHCP clients and the DHCP server are not in the same
broadcast domain. During the initial IP address leasing, the OLT helps to relay network information

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