UMN:CLI
User Manual
V5824G
300
To restore the DHCP snooping binding entries from a TFTP server, use the following
command.
Command
Mode
Description
ip dhcp snooping database
renew
A.B.C.D
Global
Reads the current DHCP snooping database file from a
TFTP server.
A.B.C.D: TFTP server address
ip dhcp snooping database
renew auto
{
on
|
off
}
Enables/disables the system to be automatically
restored the DHCP snooping DB file from the TFTP
server after a restart or reload of the switch.
ip dhcp snooping database
renew auto retry
<1-50>
Specifies the maximum number of retry attempts to
automatically restore the DHCP snooping DB file from
the TFTP server.
1-50: retry count (default: 10 times)
The file of DHCP snooping database entries is stored in a remote location accessible
through TFTP
.
8.5.7.9
ARP Inspection Start Time
This function sets the time before ARP inspection starts to run. Before setting this, ARP
inspection should be turned on. ARP inspection checks validity of incoming ARP packets
by using DHCP snooping binding table and denies the ARP packets if they are not
identified in the table.
However, the V5824G may be rebooted with any reason, then DHCP snooping binding
table entries, which are dynamically learned from DHCP packets back and forth the
V5824G, would be lost. Thus, ARP inspection should be delayed to start during some time
so that DHCP snooping table can build entries. If no time given, ARP inspection sees
empty snooping table and drop every ARP packet.
To specify the ARP inspection delay time, use the following command.
Command
Mode
Description
ip dhcp snooping arp-inspection
start
<1-2147483637>
Global
Configures the ARP inspection delay time. If reboot,
ARP inspection resumes after the time you configure.
1-2147483637: delay time (unit: second)
no ip dhcp snooping arp-
inspection start
Delete the configured ARP inspection delay time.
8.5.7.10
DHCP Snooping with Option82
In case of L2 environment, when forwarding DHCP messages to a DHCP server, a DHCP
switch can insert or remove DHCP option82 data on the DHCP messages from the clients.
In case of a switch is enabled with DHCP snooping, it floods DHCP packets with DHCP
option82 field when the DHCP option82 is enabled. This allows an enhanced security and
efficient IP assignment in the Layer 2 environment with a DHCP option82 field.
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