Dhcp Relay Overview - Alcatel-Lucent OmniSwitch 6800 Series Network Configuration Manual

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Configuring DHCP Relay

DHCP Relay Overview

The DHCP Relay service, its corresponding port numbers, and configurable options are as follows:

DHCP Relay Service: BOOTP/DHCP

UDP Port Numbers 67/68 for Request/Response

Configurable options: DHCP server IP address, Forward Delay, Maximum Hops, Forwarding Option,

automatic switch IP configuration

The port numbers indicate the destination port numbers in the UDP header. The DHCP Relay will verify

that the forward delay time (specified by the user) has elapsed before sending the packet down to UDP

with the destination IP address replaced by the address (also specified by the user).

If the relay is configured with multiple IP addresses, then the packet will be sent to all IP address destina-

tions. The DHCP Relay also verifies that the maximum hop count has not been exceeded. If the forward

delay time is not met or the maximum hop count is exceeded, the BOOTP/DHCP packet will be discarded

by the DHCP Relay.

The forwarding option allows you to specify if the relay should operate in the standard, per-VLAN only,

or AVLAN-only mode. The standard mode forwards all DHCP packets on a global relay service. The per-

VLAN only mode forwards DHCP packets that originate from a specific VLAN. The AVLAN-only mode

only forwards packets received on authenticated ports from non-authenticated clients. See

Relay Forwarding Option" on page 22-11

An additional function provided by the DHCP Relay service enables automatic IP address configuration

for default VLAN 1 when an unconfigured switch boots up. If this function is enabled, the switch broad-

casts a BootP or a DHCP request packet at boot time. When the switch receives an IP address from a

BootP/DHCP server, the address is assigned to default VLAN 1. See

tion" on page 22-12

Alternately the relay function may be provided by an external router connected to the switch; in this case,

the relay would be configured on the external router.

OmniSwitch 6800/6850/9000 Network Configuration Guide

for more information.

"Enabling Automatic IP Configura-

DHCP Relay Overview

"Setting the