SupportDocumentationWLANACAirEngine 9700Configuration & CommissioningConfiguration Guide

Wireless Access Controller (AC and Fit AP) V200R019C00 CLI-based Configuration Guide

Troubleshooting DHCP

Troubleshooting DHCP

DHCP Clients Cannot Obtain IP Addresses When the Device Functions as the DHCP Server

Fault Description

When the wireless access controller functions as the DHCP server, the DHCP client cannot obtain IP addresses.

Procedure

  1. Run the display current-configuration | include dhcp enable command to check whether DHCP is enabled. By default, DHCP is disabled.

    • If no DHCP information is displayed, DHCP is disabled. Run the dhcp enable command to enable DHCP.
    • If dhcp enable is displayed, DHCP is enabled. Go to step 2.

  2. In the wireless access controller interface view, run the display this command to check whether the DHCP address assignment mode is set.

    Command Output

    Description

    Follow-up Operation

    dhcp select global

    The DHCP server has assigned IP addresses to clients from the global address pool.

    Go to step 3.

    dhcp select interface

    The DHCP server has assigned IP addresses to clients from the interface address pool.

    Go to step 4.

    The preceding information is not displayed.

    The DHCP address assignment mode is not set on the VLANIF interface.

    Run the dhcp select global or dhcp select interface command to set the DHCP address assignment mode on the interface.

  3. Run the display ip pool command to check whether the global address pool has been created.

    • If the global address pool has not been created, run the ip pool ip-pool-name and network ip-address [ mask { mask | mask-length } ] commands to create a global address pool and set the range of IP addresses that can be dynamically assigned.
    • If the global address pool has been created, obtain the value of ip-pool-name. Then run the display ip pool name ip-pool-name command to check whether the IP addresses in the global address pool are on the same network segment with the IP address on the interface.
      • If the client and server are located on the same network segment and no relay agent is deployed:
        • If IP addresses in the global address pool and the VLANIF interface IP address are located on different network segments, run the ip address ip-address { mask | mask-length } command to change the VLANIF interface IP address to be on the same network segment as IP addresses in the global address pool.
        • If IP addresses in the global address pool and the wireless access controller interface IP address are located on the same network segment, go to step 4.
      • If the client and server are located on different network segments and a relay agent is deployed:
        • If IP addresses in the global address pool and the relay agent IP address are located on different network segments, run the ip address ip-address { mask | mask-length } command to change the IP address to be on the same network segment as IP addresses in the global address pool.
        • If IP addresses in the global address pool and the relay agent interface IP address are located on the same network segment, go to step 4.

  4. Run the display ip pool [ { interface interface-pool-name | name ip-pool-name } [ start-ip-address [ end-ip-address ] | all | conflict | expired | used ] ] command to check the usage of IP addresses in the global or interface address pool. If the value of Idle (Expired) is 0, IP addresses in the address pool have been used up.

    • If the server assigns IP addresses to clients from the global address pool on the interface, re-create a global address pool where the network segment can be connected to the previous network segment but cannot overlap with the previous network segment.
    • If the DHCP server allocates IP addresses to clients from the interface address pool, you can reduce the mask length of IP address so that more IP addresses can be allocated.

DHCP Clients Cannot Obtain IP Addresses When the Device Functions as the DHCP Relay Agent

Fault Description

When the wireless access controller functions as the DHCP relay agent, the DHCP client cannot obtain IP addresses.

Procedure

  1. Run the display current-configuration | include dhcp enable command to check whether DHCP is enabled. By default, DHCP is disabled.

    • If no DHCP information is displayed, DHCP is disabled. Run the dhcp enable command to enable DHCP.
    • If dhcp enable is displayed, DHCP is enabled.

  2. In the wireless access controller interface view, run the display this command to check whether the DHCP relay function is enabled.

    • If dhcp select relay is displayed, the DHCP relay function is enabled. Go to step 3.
    • If no information is displayed, the DHCP relay function is disabled. Then run the dhcp select relay command to enable the DHCP relay function.

  3. In the wireless access controller interface view, run the display this command to check whether the DHCP server is configured on the DHCP relay agent.

    • If dhcp relay server-ip ip-address is displayed, the DHCP server IP address is configured on the DHCP relay agent.
    • If dhcp relay server-select group-name is displayed, the interface on the DHCP relay agent is bound to a DHCP server group. Go to step 4.
    • If no information is displayed, the DHCP server IP address is not configured on the DHCP relay agent. Configure the DHCP server using either of the following methods:
      • Run the dhcp relay server-ip ip-address command to configure the DHCP server IP address on the DHCP relay agent.
      • Run the dhcp-server command to add DHCP servers to the DHCP server group and run the dhcp relay server-select group-name command to bind the VLANIF interface to a DHCP server group.

  4. Run the display dhcp server group group-name command to check whether DHCP servers are configured in the DHCP server group.

    • If the Server-IP field is displayed, DHCP servers are configured in the DHCP server group.
    • If the Server-IP field is not displayed, DHCP servers are not configured in the DHCP server group. Then run the dhcp-server command to add DHCP servers to the DHCP server group.