DHCP extension on S series switches

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You can use extended DHCP functions on S series switches as follows:

# How can authorized users with static IP addresses go online?
After DHCP snooping and IPSG functions are enabled (using the ip source check user-bind enable command) on the switch, if an authorized user connects to the switch using a static IP address, the switch will discard packets of the user because there is no matching dynamic binding entry. As a result, the user cannot go online. In this case, you can run a command to configure a static binding entry for the user:
In the system view, run user-bind static { { { ip-address | ipv6-address } { start-ip [ to end-ip ] } &<1-10> | ipv6-prefix prefix/prefix-length } | mac-address mac-address } * [ interface interface-type interface-number ] [ vlan vlan-id [ ce-vlan ce-vlan-id ] ].
When configuring a static binding entry, select at least two of the four elements: IP address, MAC address, interface, and VLAN. The switch allows you to bind all the four elements.
After the static binding entry is created for the user, the user can go online. If the user changes the IP address, the original static binding entry will become invalid. As there is no matching dynamic or static binding entry for this user, the user cannot go online.

Other related questions:
DHCP functions of S series switches
DHCP dynamically configures and uniformly manages network parameters of hosts on a TCP/IP network. DHCP provides the following functions: - Dynamic allocation: DHCP allocates an IP address with a limited validity period (called lease) to a client. This mechanism applies to hosts that temporarily connect to a network with fewer IP addresses than the total number of hosts and hosts do not need to permanently connect to the network. For example, this mechanism can be used to allocate IP addresses to laptops used by employees on business trips or mobile terminals in cafes. - Static allocation: Fixed IP addresses are assigned to specified hosts. This mechanism applies to hosts with special IP address requirements. For example, the file server of an enterprise needs to use a fixed IP address to provide services for extranet users. Compared with manual IP address configuration, DHCP static allocation prevents manual configuration errors and helps network administrators perform unified maintenance and management. DHCP can allocate other network parameters except for the IP address to hosts, including the DNS server address, routing information, and gateway address.

DHCP configuration on S series switch does not take effect
DHCP configuration may not take effect on an S series switch due to the following reasons: 1. DHCP server is disabled on the switch. 2. The DHCP address pool is configured incorrectly. 3. No IP network segment is specified on the interface connected to DHCP clients, or the specified IP network segment is on a different network segment from the address pool. 4. If ACL resources are exhausted, the DHCP commands run globally or on an interface will not take effect.

Check DHCP information on S series switches
Method to check DHCP information on S series switches: - Run the display ip pool [ name ip-pool-name [ start-ip-address [ end-ip-address ] | all | conflict | expired | used ] ] command to check address allocation in interface address pool mode. - Run the display ip pool [ name ip-pool-name [ start-ip-address [ end-ip-address ] | all | conflict | expired | used ] ] command to check address allocation in global address pool mode. - Run the display dhcp server database command to check the names and directories of files in which DHCP data is saved. - Run the display nat-policy template [ template-name ] command to check the configuration of the DHCP Option template. - Run the display dhcp relay { all | interface interface-type interface-number } command to check DHCP server or DHCP server group information on the interface configured with the DHCP relay function. - Run the display dhcp server group [ group-name ] command to check the configuration of the DHCP server group. - Run the display dhcp client command to check information about DHCP clients. - Run the display dhcp server statistics command to check statistics on received and sent DHCP packet by the switch used as the DHCP server. - Run the display dhcp relay statistics command to check statistics on received and sent DHCP packet by the switch used as the DHCP relay agent. - Run the display dhcp client statistics [ interface interface-type interface-number ] command to check statistics on received and sent DHCP packet by the switch used as the DHCP client. - Run the display dhcp statistics command to check statistics on received and sent DHCP packet by the switch.

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