Configuring an address allocation mode for a common address pool
![[CAUTION: ]](images/caution.png) | CAUTION: You can configure either the static binding or dynamic address allocation for a common address pool as needed. | |
You must specify an address range for the dynamic address allocation. A static binding is a special address pool containing only one IP address.
Configuring static address allocation
Some DHCP clients such as a WWW server need fixed IP addresses. You can create a static binding of a client's MAC or ID to IP address in the DHCP address pool.
When the client with the MAC address or ID requests an IP address, the DHCP server will find the IP address from the binding for the client.
A DHCP address pool now supports only one static binding, which can be a MAC-to-IP or ID-to-IP binding.
Follow these steps to configure a static binding in a common address pool:
To do… | Use the command… | Remarks | |
|---|---|---|---|
Enter system view | system-view | — | |
Enter common address pool view | dhcp server ip-pool pool-name | — | |
Specify the IP address of the binding | static-bind ip-address ip-address [ mask-length | mask mask ] | Required No IP addresses are statically bound by default. | |
Specify the MAC address or client ID | Specify the MAC address | static-bind mac-address mac-address | Required to configure either of the two Neither is bound statically by default. |
Specify the client ID | static-bind client-identifier client-identifier | ||
Specify the lease duration for the IP address | expired { day day [ hour hour [ minute minute ] ] | unlimited } | Optional By default, the lease duration of an IP address is unlimited. | |
![[NOTE: ]](images/note.png) | NOTE: Use the static-bind ip-address command together with static-bind mac-address or static-bind client-identifier to accomplish a static binding configuration. In a DHCP address pool, if you execute the static-bind mac-address command before the static-bind client-identifier command, the latter will overwrite the former and vice versa. If you use the static-bind ip-address, static-bind mac-address, or static-bind client-identifier command repeatedly in the DHCP address pool, the new configuration will overwrite the previous one. The IP address of the static binding cannot be an interface address of the DHCP server. Otherwise, an IP address conflict may occur and the bound client cannot obtain an IP address correctly. The ID of the static binding must be identical to the ID displayed by using the display dhcp client verbose command on the client. Otherwise, the client cannot obtain an IP address. When the switch serves as a DHCP client or BOOTP client, you need to configure the static binding of the DHCP client's ID to IP address, or the static binding of the BOOTP client's MAC to IP address on the DHCP server; otherwise, the DHCP or BOOTP client cannot obtain a static IP address. If the interfaces on a DHCP client share the same MAC address, you need to specify the client ID, rather than MAC address, in a static binding to identify the requesting interface; otherwise, the client may fail to obtain an IP address. | |
Configuring dynamic address allocation
For dynamic address allocation, you must configure a DHCP address pool, specify one and only one address range for the pool, and specify the lease duration. A DHCP address pool can have only one lease duration.
To avoid address conflicts, configure the DHCP server to exclude IP addresses used by the gateway or FTP server from dynamic allocation.
Follow these steps to configure dynamic address allocation for a common address pool:
To do… | Use the command… | Remarks |
|---|---|---|
Enter system view | system-view | — |
Enter common address pool view | dhcp server ip-pool pool-name | — |
Specify a subnet | network network-address [ mask-length | mask mask ] | Required Not specified by default. |
Specify the address lease duration | expired { day day [ hour hour [ minute minute ] ] | unlimited } | Optional One day by default. |
Return to system view | quit | — |
Exclude IP addresses from automatic allocation | dhcp server forbidden-ip low-ip-address [ high-ip-address ] | Optional Except IP addresses of the DHCP server interfaces, all addresses in the DHCP address pool are assignable by default. |
| NOTE: In common address pool view, using the network command repeatedly overwrites the previous configuration. After you exclude IP addresses from automatic allocation by using the dhcp server forbidden-ip command, neither a common address pool nor an extended address pool can assign these IP addresses through dynamic address allocation. Using the dhcp server forbidden-ip command repeatedly can exclude multiple IP address ranges from allocation. | |