How often does the switch automatically back up the DHCP snooping binding table

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A chassis switch automatically backs up the DHCP snooping binding table every hour; a box switch automatically backs up the table every 24 hours. From V200R003C00, the interval for automatically backing up the DHCP snooping binding table can be configured.

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Automatic backup of DHCP snooping binding table on S series switch
For S series switches in V200R003C00 and later versions, you can run the dhcp snooping user-bind autosave file-name [ write-delay delay-time ] command to enable automatic backup of the DHCP snooping binding table and specify the backup interval. By default, local automatic backup of the DHCP snooping binding table is disabled. By default, S series modular switches and fixed switches back up the DHCP snooping binding table every 1 hour and every 24 hours, respectively.

Generation of dynamic DHCP snooping binding entries on S series switch
Information about generating DHCP snooping binding entries is as follows: - When the dhcp snooping enable command is not run on the user-side interface and the network-side interface is not configured as a trusted interface, users can go online, but no DHCP snooping binding entry is generated. - When the dhcp snooping enable command is not run on the user-side interface and the network-side interface is configured as a trusted interface, users can go online, but no DHCP snooping binding entry is generated. - When the dhcp snooping enable command is run on the user-side interface and the network-side interface is not configured as a trusted interface, users cannot go online, but no DHCP snooping binding entry is generated. - When the dhcp snooping disable command is run on the user-side interface, users can go online, but no DHCP snooping binding entry is generated no matter whether the network-side interface is configured as a trusted interface. - When the dhcp snooping enable command is run on the user-side interface and both user-side and network-side interfaces are configured as trusted interfaces, users can go online, but no DHCP snooping binding entry is generated. - If the DHCP snooping function has been enabled but no DHCP snooping entry is generated, you can check the device configuration in the preceding aspects.

Configuring an S series switch to save the configuration file to a server periodically
To enable an S series switch (except the S1700) to periodically save its configuration file to a server, perform the following configurations: 1. Set information about the server to which the configuration file is to be automatically saved. Set the file transfer mode to FTP, FTP server IP address to 1.1.1.1, user name to admin1234, and password to Helloworld@6789. system-view [HUAWEI] set save-configuration backup-to-server server 1.1.1.1 transport-type ftp user admin1234 password Helloworld@6789 2. Set the interval for the system to save new configurations automatically to 60 minutes. [HUAWEI] set save-configuration interval 60

Configure binding tables for IPSG (user-bind binding tables) on S series switches
Configure a binding table for IPSG (user-bind binding table) on an S series switch (except the S1700) as follows: �?Static binding table A static binding entry contains at least one of the following: IP address, MAC address, interface, VLAN, and IP address and MAC address. An interface cannot be bound to a VLAN to form a binding entry. For example, configure a static binding entry of VLAN 2 and IP address 1.1.1.1. [HUAWEI] user-bind static ip-address 1.1.1.1 vlan 2 Note: Static binding entries can be configured only in the system view. �?Dynamic binding table Enable DHCP snooping globally and on an interface. Generally, the interface directly or indirectly connected to the DHCP server or gateway is configured as a trusted interface. After DHCP snooping is enabled and the trusted interface is configured, user-side interfaces automatically generate dynamic binding entries based on received DHCP ACK packets. For example, enable DHCP snooping globally and on GE0/0/1, and configure G0/0/1 as a trusted interface. [HUAWEI] dhcp enable [HUAWEI] dhcp snooping enable [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] dhcp snooping enable [HUAWEI-GigabitEthernet0/0/1] dhcp snooping trusted Note: If both DHCP relay and VRRP are configured on a switch, DHCP snooping cannot be enabled. DHCP snooping cannot be enabled if the DHCP server is at the subordinate VLAN side and the DHCP client is at the principle VLAN side. After DHCP snooping is configured, the switch generates DHCP snooping entries for the hosts when the hosts go online again. Then IPSG takes effect. If you enable IPSG before the switch generates DHCP snooping dynamic binding entries, the switch rejects all packets except DHCP Request packets. In this situation, the hosts with dynamic IP addresses cannot communicate with each other. Therefore, before enabling the IPSG function, configure the DHCP snooping function to enable the switch to generate dynamic binding entries.

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