H3C Technologies H3C S12500 Series Switches - Manual (Page 78)

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Configuring the DHCP relay agent to release an IP
address
You can configure the relay agent to release a client's IP address. The relay agent sends a
DHCP-RELEASE message that contains the specified IP address. Upon receiving the DHCP-RELEASE
message, the DHCP server releases the IP address. Meanwhile, the client entry is removed from the
DHCP relay agent.
To configure the DHCP relay agent in system view to send DHCP-RELEASE messages:
Step Command
1. Enter system view. system-view
2. Configure the DHCP relay agent to release an IP
address.
dhcp relay release ip client-ip
NOTE:
•
The IP address to be released must be available in a dynamic client entry.
• Dynamic client entries can be generated only after you enable address check, authorized ARP, or IP
source guard on the DHCP relay agent. For more information about IP source guard, see
Security
Configuration Guide.
Configuring the DHCP relay agent to support
Option 82
Configuration prerequisites
Before configure the DHCP relay agent to support Option 82, complete the following tasks:
1. Enable DHCP.
2. Enable the DHCP relay agent on the specified interface.
3. Correlate a DHCP server group with relay agent interfaces.
Configuration guidelines
• To support Option 82, perform related configuration on both the DHCP server and relay agent. For
DHCP server configuration of this kind, see " Configuring the DHCP server ."
• If the handling strategy of the DHCP relay agent is configured as replace, configure a padding
format for Option 82. If the handling strategy is keep or drop, you need not configure any padding
format.
• If sub-option 1 (node identifier) of Option 82 contains the device name (sysname) of a node, the
device name must contain no spaces. Otherwise, the DHCP relay agent will drop the message.