Enabling periodic refresh of dynamic relay entries

A DHCP client unicasts a DHCP-RELEASE message to the DHCP server to release its IP address. The DHCP relay agent conveys the message to the DHCP server and does not remove the IP-to-MAC entry of the client.

With this feature, the DHCP relay agent uses the following information to periodically send a DHCP-REQUEST message to the DHCP server:

• The IP address of a relay entry.

• The MAC address of the DHCP relay interface.

The relay agent maintains the relay entries depending on what it receives from the DHCP server:

• If the server returns a DHCP-ACK message or does not return any message within an interval, the DHCP relay agent removes the relay entry. In addition, upon receiving the DHCP-ACK message, the relay agent sends a DHCP-RELEASE message to release the IP address.

• If the server returns a DHCP-NAK message, the relay agent keeps the relay entry.

1. Enter system view.

   system-view

2. Enable periodic refresh of dynamic relay entries.

   dhcp relay client-information refresh enable

   By default, periodic refresh of dynamic relay entries is enabled.

3. (Optional.) Set the refresh interval.

   dhcp relay client-information refresh [ auto | interval interval ]

   By default, the refresh interval is auto, which is calculated based on the number of total relay entries.