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No IP Address Is Allocated to an AP
Possible Cause
- The network between an AP and the DHCP server fails, which may be caused by incorrect VLAN configurations (as an example).
- The DHCP configuration is incorrect.
- No DHCP address pool is configured, or available IP addresses in a DHCP address pool are insufficient.
Troubleshooting Procedure
# Run commands on the DHCP server to check whether the AP is assigned an IP address. In this example, the AC functions as a DHCP server.
- Check whether the link between the AP and AC is normal. For details, see The Network Between the AP and AC Fails.
- If a DHCP relay agent is deployed, perform a ping operation using the IP address of the DHCP server as the source IP address and that of the DHCP relay agent as the destination IP address. If the ping operation fails, an error occurs in the route configuration. Check the route configuration.
- Run the display ip pool { interface interface-pool-name | name ip-pool-name } used command to check IP address allocation. Check whether the AP has obtained an IP address based on the MAC address. Check whether available IP addresses in the address pool are abundant.
[AC] display ip pool interface Vlanif1219 used Pool-name : Vlanif1219 Pool-No : 4 Lease : 1 Days 0 Hours 0 Minutes Domain-name : - DNS-server0 : - NBNS-server0 : - Netbios-type : - Position : Interface Status : Unlocked Gateway-0 : 10.1.1.2 Network : 10.1.0.0 Mask : 255.255.240.0 VPN instance : -- Conflicted address recycle interval: - ----------------------------------------------------------------------------- Start End Total Used Idle(Expired) Conflict Disable ----------------------------------------------------------------------------- 10.1.0.1 10.1.15.254 4093 4 4084(0) 5 0 ----------------------------------------------------------------------------- Network section : ----------------------------------------------------------------------- Index IP MAC Lease Status ----------------------------------------------------------------------- 4085 10.1.15.246 dcd2-fc9a-c800 7375 Used 4086 10.1.15.247 1047-80af-fbc0 7369 Used 4087 10.1.15.248 dcd2-fcf4-6420 7929 Used 4090 10.1.15.251 dcd2-fc22-d880 9368 Used -----------------------------------------------------------------------If the address pool resources on the DHCP server are insufficient, you can increase the number of IP addresses or reduce the IP address lease.
- Run the display arp command to view all ARP mapping entries. Check whether the AP has obtained an IP address based on the MAC address. If so, run the ping command to ping the obtained IP address.
[AC] display arp IP ADDRESS MAC ADDRESS EXPIRE(M) TYPE INTERFACE VPN-INSTANCE VLAN/CEVLAN PVC ------------------------------------------------------------------------------ ...... 10.1.1.2 0200-0000-0017 I - Vlanif1219 10.1.15.251 dcd2-fc22-d880 2 D-0 GE0/0/1 1219/- 10.1.15.247 1047-80af-fbc0 16 D-0 GE0/0/1 1219/- 10.1.15.246 dcd2-fc9a-c800 15 D-0 GE0/0/1 1219/- 10.1.15.248 dcd2-fcf4-6420 6 D-0 GE0/0/1 1219/- 10.1.1.219 4c1f-cc6b-c248 16 D-0 GE0/0/1Ping the IP address mapping the MAC address. If the ping operation succeeds, the AP has obtained an IP address. Otherwise, the IP address obtained by the AP has expired or the AP fails to obtain an IP address.[AC] ping 10.1.15.251 PING 10.1.15.251: 56 data bytes, press CTRL_C to break Reply from 10.1.15.251: bytes=56 Sequence=1 ttl=255 time=1 ms Reply from 10.1.15.251: bytes=56 Sequence=2 ttl=255 time=1 ms Reply from 10.1.15.251: bytes=56 Sequence=3 ttl=255 time=1 ms Reply from 10.1.15.251: bytes=56 Sequence=4 ttl=255 time=1 ms Reply from 10.1.15.251: bytes=56 Sequence=5 ttl=255 time=1 ms --- 10.1.15.251 ping statistics --- 5 packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 1/1/1 ms - Check whether the DHCP configuration is correct. For details about how to configure DHCP, see Configuring an AP to Go Online in DHCP Mode.
