Configuring the dhcp relay agent, Dhcp relay agent configuration task list, Enabling dhcp – H3C Technologies H3C S3600 Series Switches User Manual

Page 675

3-4

the XID (Transaction ID, a random value selected by the client to uniquely identify an address allocation

process) in the message, and then forward the message to the DHCP server.

After receiving the message, the DHCP server returns a DHCP-ACK message to the client:

If the DHCP-ACK message is unicast, the DHCP relay agent directly forwards the message to the

client without replacing the XID in the message.

If the DHCP-ACK message is broadcast, the DHCP relay agent delivers the message to the CPU

to replace the XID, and then forwards the message to the client.

A DHCP client can only handle a DHCP-ACK message which has the same XID as that in the DHCP

Inform message sent by the client. Therefore, to ensure clients to obtain configuration parameters

successfully, S3600 series Ethernet switches support the DHCP Inform message handling feature. With

this feature enabled, an S3600 series switch that functions as a DHCP relay agent in a fabric can

replace the XID in DHCP Inform messages before forwarding them to the DHCP server. If this feature is

disabled, the switch does not replace the XID.

Configuring the DHCP Relay Agent

If a switch belongs to an IRF fabric, you need to enable the UDP Helper function on it before

configuring it as a DHCP relay agent.

If an S3600 Ethernet switch is configured with DHCP Relay Agent, the clients connected to it

cannot dynamically obtain IP addresses through BOOTP.

DHCP Relay Agent Configuration Task List

Complete the following tasks to configure the DHCP relay agent:

Task

Remarks

Enabling DHCP

Required

Required

Optional

Optional

Optional

Enabling DHCP

Make sure to enable DHCP before you perform other DHCP relay-related configurations, since other

DHCP-related configurations cannot take effect with DHCP disabled.

This manual is related to the following products: