Configuring Automatic User Login

Usage Scenario

In a Dynamic Host Configuration Protocol version 4 (DHCPv4) user access scenario, when the router is restarted or its board, subcard, or interface is faulty, DHCPv4 users are logged out and their information is lost. If a DHCPv4 client does not detect the fault, the DHCPv4 client does not resend a DHCP request packet to the router or redial up after the fault is rectified. As a result, the DHCPv4 user cannot go online again. To prevent this issue, configure automatic user login. After this configuration, user information is saved automatically to the memory before any fault occurs, and the users can go online automatically after the fault is rectified.

If the router is powered off and restarted, user information saved in the high-end memory will be lost. Before the router is powered off, write the user information saved in the high-end memory to the CF card. After the router is restarted, restore the user information saved in the CF card to the high-end memory.

The following DHCPv4 user information is saved: MAC address, IP address, VLAN/PVC, access interface, VPN instance name, domain name, lease, Option 82, Option 60, Option 61, and IP address of the DHCPv4 server. The DHCPv4 user information is used only when the DHCPv4 users go online automatically. To ensure security, do not save DHCPv4 user information in the CF card for a long time and clear it in time.

Procedure

Run system-view
The system view is displayed.
Run access-user dhcp auto-save enable max-user-number max-user-number
Automatic backup of DHCPv4 user information is enabled globally, and the maximum number of DHCPv4 users whose information can be backed up in all domains is specified.

The device backs up only information about the configured maximum number of DHCPv4 users in all domains. The excessive part of DHCPv4 user information is not backed up. Specify max-user-number as the total number of DHCPv4 users whose information needs to be backed up in all domains.

The access-user dhcp auto-save command applies for a memory space based on the maximum number of DHCPv4 users. If the command cannot apply for the size of contiguous memory space, the command fails to be executed, and automatic backup of DHCPv4 user information is disabled.
Run aaa
The AAA view is displayed.
Run domain domain-name
The AAA domain view is displayed.
Run access-user dhcp auto-save enable
Automatic backup of DHCPv4 user information is enabled in the domain.

Information about online DHCPv4 users in the domain is saved in the high-end memory, which is a storage medium. The larger the configured maximum number of the DHCPv4 users, the more memory space the user information takes up. For example, information about 64000 DHCPv4 users takes up 50 MB of memory.

In a dual-system hot backup scenario, DHCPv4 user information is backed up using the dual-system hot backup mechanism, so the device does not save information about these DHCPv4 users in the high-end memory.
Run quit
Return to the AAA view.
Run access-trigger lease-end-time original
The router is configured to apply the original lease time to users that go online again after going offline abnormally.
Run quit
Return to the system view.
Run access-user dhcp auto-recover enable
Automatic DHCPv4 user login is enabled.
(Optional) Run access-user dhcp auto-recover nosend-packet
The device is disabled from sending DHCPv4 messages to a remote DHCPv4 server when users automatically re-log in to the device after the device recovers from a fault. This prevents user login failures caused by IP address conflicts.
(Optional) Run access-user dhcp auto-recover speed { slow | normal | fast }
The rate at which DHCPv4 users automatically go online after the router recovers from a fault is configured.
- If slow is configured, the maximum rate at which DHCPv4 users automatically go online after the router recovers from a fault is 100/s.
- If normal is configured, the maximum rate at which DHCPv4 users automatically go online after the router recovers from a fault is 300/s.
- If fast is configured, the maximum rate at which DHCPv4 users automatically go online after the router recovers from a fault is 500/s.
To allow users to go online automatically after the router is powered off and restarted, perform the following operations additionally:
1. Before the device is powered off, run access-user dhcp save-file file-path-name
  
  DHCPv4 user information saved in the high-end memory is written to the CF card, and the directory and file name are specified.
  
  If there is a large amount of DHCPv4 user information saved in the high-end memory, it takes a long time for the access-user dhcp save-file command to write the information to the CF card, which may affect services. Exercise caution when you run this command.
2. After the device is restarted, run access-user dhcp recover-file file-path-name
  
  DHCPv4 user information saved in the CF card is restored to the high-end memory.
  
  The device reads DHCPv4 user information in the CF card and saves the information in the high-end memory. The new information does not override the original DHCPv4 user information saved in the high-end memory.
Run commit
The configuration is committed.

Verifying the Configuration

Run the display access-user auto-save user-info { online | wait-recover | mac-address mac-address [ interface { interface-name | interface-type interface-number } [ pevlan pevlan cevlan cevlan ] ] } command to check DHCPv4 user information saved in the high-end memory.

Run the display access-user auto-save statistics command to check statistics about DHCPv4 user information saved in the high-end memory after automatic backup is enabled.