Shulou(Shulou.com)06/01 Report--

For DHCP failures, I believe administrators have encountered, this article will introduce 3 tips and steps to deal with DHCP failures.

First: check whether the physical connection is open.

Configure the IP address on the network card connected between the client and the server to ensure that the IP address is in the same network segment as the IP address of the server-side interface GigabitEthernet1/0/0. From the IP address of the client ping GigabitEthernet1/0/0 interface, if ping is available, the connection is open and the physical line failure can be eliminated. You can also turn on the debug switch of DHCP on the server side to see if you can receive the DHCPDISCOVER message from the client.

Second: whether the configuration of the DHCP server is correct.

1. Execute the command dhcp enable.

two。 Execute the command display dhcp server tree all to see if the global address pool exists and that the IP address in the pool is on the same network segment as the IP address of interface GigabitEthernet1/0/0. If it does not exist, execute the command dhcp server ip-pool pool-name and the command network ip-address [mask {mask mask-length}] to create a pool of addresses and configure a dynamically assignable range of IP addresses in the pool. If the address pool exists, but the IP address in the pool is not on the same network segment as the IP address of interface GigabitEthernet1/0/0, modify the IP address in the pool or modify the IP address of interface GigabitEthernet1/0/0 so that they are in the same network segment.

3. Execute the command dhcp select global {all interface interface-type interface-number} under the system view or dhcp select global under the GigabitEthernet1/0/0 interface view to ensure that the customer under GigabitEthernet1/0/0 gets the address from the global address pool.

Third: whether there are available IP addresses, expired IP addresses, or conflicting IP addresses in the pool.

1. Execute the command display dhcp server free-ip to check if there are any available IP addresses in the global address pool.

two。 If no address is available, execute the command display dhcp server expired pool pool-name to see if there is an expired IP address.

3. If no expired IP address exists, execute the command display dhcp server conflict all to see if there is a conflicting IP address. If so, check to see if the detection time (Discover Time) has exceeded 1 hour. In the implementation of NE80E/40E, if a conflicting IP address is found, we can reassign the IP address after an hour. When there is a conflicting IP address and the probe time does not exceed 1 hour, the command reset dhcp server conflict all is executed to release the conflicting IP address. If there is no conflicting IP address, the available IP address, expired IP address and conflicting IP in the address pool do not exist, which means that the IP address in the address pool has been exhausted, and a global address pool can be recreated. The Network of this address pool overlaps with the Network of the previous address pool, and the network segment is larger than the network segment of the previous address pool.

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