DHCP configuration is ineffective on an AR

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The possible causes for ineffective DHCP configuration as follows:
1. DHCP is not enabled on the AR.
2. The address pool is configured incorrectly.3. The IP network segment are not specified on the interface of the DHCP server connected to the client, or the specified IP network segment and address pool are different.
4. If ACL resources are used up, the DHCP command that is run globally or on an interface does not take effect.

Other related questions:
Method used to configure NAT and DHCP on the AR
Huawei AR series routers support DHCP and NAT so that users can dynamically obtain IP addresses and access the Internet. This function applies to all versions and models of the AR.

DHCP configuration does not take effect on the AR
Possible causes are as follows: 1. DHCP is not enabled on the AR. 2. The address pool is configured incorrectly. 3. The IP network segment is not specified on the interface of the DHCP server connected to the client, or the specified IP network segment and address pool are different. 4. If ACL resources are used up, the DHCP command that is run globally or on an interface does not take effect.

Method used to configure DHCP client on the AR
The AR can function as a DHCP client to dynamically obtain configuration parameters such as an IP address from a DHCP server. This reduces the configuration costs and the errors and facilitates centralized management. Assume that RouterA functions as the DHCP client and RouterB as the DHCP server. The configuration is as follows: 1. Configure RouterA. [HUAWEI] dhcp enable //Enable the DHCP function. [HUAWEI] interface GigabitEthernet0/0/0 [HUAWEI-GigabitEthernet0/0/0] ip address dhcp-alloc //Enable the DHCP client on an interface. [HUAWEI-GigabitEthernet0/0/0] quit 2. Configure RouterB. [HUAWEI] dhcp enable //Enable the DHCP function. [HUAWEI] ip pool p1 [HUAWEI-ip-pool-p1] gateway-list 10.202.1.1 //Configure the gateway IP address. [HUAWEI-ip-pool-p1] network 10.202.1.0 mask 255.255.255.0 //Specify the range of IP addresses that can be dynamically allocated in the global address pool. [HUAWEI-ip-pool-p1] quit [HUAWEI] interface GigabitEthernet0/0/0 [HUAWEI-GigabitEthernet0/0/0] ip address 10.202.1.1 255.255.255.0 [HUAWEI-GigabitEthernet0/0/0] dhcp select global //Configure the global address pool mode. 3. Verify the configuration. Run the display ip interface brief command on RouterA to view the IP address that GE0/0/0 has obtained.

How is DHCP Option 43 configured on an AR
Option 43 is a vendor specific information option. If an AP and an AC are located on different network segments, the AP cannot discover the ACs through broadcast. To address this problem, configure Option 43 on the DHCP server to advertise AC's IP addresses to the AP. The AR functions as the DHCP server and the AC's IP address is 192.168.22.1. The configuration of Option 43 is as follows: - Based on the global address pool: [Huawei] dhcp enable [Huawei] ip pool huawei [Huawei-ip-pool-huawei] network 192.168.100.0 255.255.255.0 [Huawei-ip-pool-huawei] gateway-list 192.168.100.1 [Huawei-ip-pool-huawei] option 43 sub-option 3 hex 31302E31302E31302E31 //Run the option 43 sub-option 3 ascii 192.168.22.1 command. - Based on the interface address pool: [Huawei] dhcp enable [Huawei] interface gigabitethernet 1/0/0 //Enter the view of the interface connected to the AP. [Huawei-GigabitEthernet1/0/0] ip address 10.10.10.10 24 [Huawei-GigabitEthernet1/0/0] dhcp select interface [Huawei-GigabitEthernet1/0/0] dhcp server 43 sub-option 3 hex 31302E31302E31302E31 //Run the dhcp server option 43 sub-option 3 ascii 192.168.22.1 command. If an Option 43 contains multiple AC IP addresses, the IP addresses are separated by commas (,). The ASCII value of commas (,) is 2C. For example, if the ACs' IP addresses are 192.168.22.1 and 192.168.22.2, run the option 43 sub-option 3 hex 3139322E3136382E3130302E322C3139322E3136382E3130302E33 or option 43 sub-option 3 ascii 192.168.22.1,192.168.22.2 command.

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