Check DHCP IP address lease on S series switch


On S series switches except S1700 switches, you can view the lease of IP addresses in an address pool as follows:
- If an interface address pool is used, run the display ip pool interface interface-pool-name [ start-ip-address [ end-ip-address ] ] command.
- If a global address pool is used, run the display ip pool name ip-pool-name [ start-ip-address [ end-ip-address ] ] command.
The Lease field in the command output indicates the lease of IP addresses.

Other related questions:
DHCP address lease configuration on S series switch
For S series switches (except S1700 switches), IP addresses that are dynamically allocated by a DHCP server have leases. The lease is configurable and defaults to 1 day. IP address leases can be specified for global and interface address pools. For example, to set the IP address lease of the address pool pl to 10 days, perform the following configuration: - Global address pool [HUAWEI] ip pool p1 [HUAWEI-ip-pool-p1] lease day 10 - Interface address pool [HUAWEI] interface vlanif 10 [HUAWEI-Vlanif10] dhcp select interface [HUAWEI-Vlanif10] dhcp server lease day 10 Different address pools on a DHCP server can be configured with different IP address leases, but IP addresses in the same address pool must have the same lease.

Method to release DHCP address pool and configure the lease on S series switches
S series switches excluding the S1700 allow the DHCP address pool to be manually released and support configurable lease for IP addresses dynamically assigned through DHCP.

IP addresses in a DHCP address pool on S series switch are exhausted
If the number of allocatable IP addresses in the address pool exceeds the number of DHCP clients connected to the DHCP server, the address pool resources may be exhausted in the following situation: - Many attackers apply for IP addresses or an attacker applies for many IP addresses by changing the CHADDR field in DHCP Discover messages. In this case, configure DHCP snooping. - The DHCP server ping function has been configured on the DHCP server. This function allows the switch to ping allocated IP addresses before sending DHCP Offer messages. Any reply to the ping packets may cause the DHCP server to consider that an IP address conflict occurs, resulting in exhaustion of address pool resources. To solve this problem, use either of the following methods: 1. Configure port mirroring on the DHCP server to obtain the packet header, and determine whether address pool exhaustion is caused by the second reason. If yes, disable the corresponding client. 2. Run the undo dhcp server ping packet command to disable the DHCP server ping function.

Whether the DHCP function of S series switch support static IP address check
After DHCP snooping is configured, S series switches do not check static IP addresses by default. You can enable the IPSG function and configure static binding entries to enable the static IP address check function.

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