(Optional) Configuring IP Address Management

IP address management includes backing up and restoring data in an address pool, configuring alarm thresholds, and reclaiming IP addresses.

Prerequisites

The DHCP server function has been enabled using the dhcp server enable command on an interface if the interface needs to be used as a DHCP server.

If multiple interfaces need to be used as DHCP servers, for security purposes, you are advised to preferentially run the dhcp server enable command on the interfaces to enable the DHCP server function. If high security is not required, you run the dhcp server request-packet all-interface enable command in the system view to enable the DHCP server function for all interfaces.
If the DHCP server function is not enabled, a DHCP server does not process DHCP request messages.

Procedure

Run system-view
The system view is displayed.
Configure DHCP data saving and restoration.
1. Run dhcp server database enable
  The system is enabled to save IP addresses assigned from a DHCP address pool to a CF card.
  
  After this command is run, the system generates and saves the lease.txt and conflict.txt files in the DHCP folder on a CF card. The lease.txt and conflict.txt files store address lease and conflict information, respectively.
  An encrypted file integrity check code is added to the lease.txt and conflict.txt files to prevent tampering. After the device restarts, the system decrypts this code and uses it to verify the file integrity before restoring the address lease and conflict information from the lease.txt and conflict.txt files. If the verification is successful, the data is restored; otherwise, it is discarded and a log is recorded.
  - If you manually modify the content of a file, run the dhcp server database authentication-mode no-check command to set the file integrity authentication mode to no-check before the restart.
  - The root keys for decrypting and encrypting the file integrity check code must be the same. Otherwise, the decryption fails. The root key on each device is unique to that device. If you use a backup file generated on another device to restore data, run the dhcp server database authentication-mode no-check command to set the file integrity authentication mode to no-check before the restart.
  - For compatibility with earlier versions, data can be restored based on an earlier version of a file that does not carry the file integrity check code after a restart. To forcibly check whether data is tampered with based on an earlier version of a file, run the dhcp server database authentication-mode force-check command to set the file integrity authentication mode to force-check before a restart.
2. Run dhcp server database write-delay interval
  The interval at which DHCP global address pool data is automatically saved is set.
3. Run dhcp server database recover
  The DHCP server is enabled to restore DHCP global address pool data from the CF card.
  
  After this function is enabled, the DHCP server restores DHCP global address pool data from the CF card after system restart.
Configure the address resource alarm function.
1. Run ip pool ip-pool-name [ server ]
  The address pool view is displayed.
2. Run warning-threshold threshold-value
  The alarm threshold for the address usage of the address pool is specified.
  
  If the address usage exceeds a specified threshold, an alarm will be generated. If the address usage falls below 90% of the alarm threshold, this alarm will be cleared.
3. Run warning-exhaust
  The address exhaustion alarm function is enabled for the address pool.
  
  When the address pool is exhausted, an alarm will be generated. When the address usage of the address pool falls below 90% of the threshold, this alarm will be cleared.
Configure the IP address reclaiming function.
1. Run recycle start-ip-address [ end-ip-address ]
  The IP address status is configured as idle.
  
  When an IP address is being used by an offline client, the IP address can be reclaimed, preventing IP address waste.
2. Run conflict auto-recycle interval interval-time
  The interval at which conflicting addresses are automatically reclaimed is set.
  If conflicting addresses exist in an address pool, the DHCP server supports automatic IP address reclaiming by default. You can configure an IP address reclaiming interval as follows:
  - If the interval-time value is not 0 and the usage of IP addresses in the address pool exceeds the alarm threshold specified in the warning-threshold command, the server automatically reclaims some conflicting IP addresses and re-assigns them to users when the address conflict time exceeds the interval-time value.
  - If the interval-time value is set to 0, the automatic address reclaim function is disabled, and conflicting addresses will not be assigned to users. In this case, you need to run the reset conflict-ip-address command to reclaim conflicting addresses.
Run lock
The address pool is locked.

If you want to delete an address pool that is currently in use, you can run this command to lock the address pool and then delete the address pool after all the users using this address pool go offline.
Run commit
The configuration is committed.