H3C Technologies H3C S10500 Series Switches - Manual (Page 89)

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• To identify DHCP packets from unauthorized DHCP servers, DHCP snooping delivers all incoming
DHCP packets to the CPU. If a malicious user sends a large number of DHCP requests to the DHCP
snooping device, the CPU of the device will be overloaded, and the device may even crash. To
solve this problem, you can configure DHCP packet rate limit on relevant interfaces.
Configuration procedure
Follow these steps to configure DHCP packet rate limit:
To do… Use the command… Remarks
Enter system view system-view —
Enter Layer 2 Ethernet port
view or Layer 2 aggregate
interface view
interface interface-type
interface-number
—
Configure the maximum rate
of incoming DHCP packets
dhcp-snooping rate-limit rate
Required
Not configured by default.
Displaying and maintaining DHCP snooping
To do… Use the command… Remarks
Display DHCP snooping entries
display dhcp-snooping [ ip ip-address ]
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Display Option 82 configuration
information on the DHCP snooping
device
display dhcp-snooping information { all |
interface interface-type interface-number }
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Display DHCP packet statistics on the
DHCP snooping device (in standalone
mode) display dhcp-snooping packet statistics
[ slot slot-number ] [ | { begin | exclude |
include } regular-expression ]
Available in any view
Display DHCP packet statistics on the
DHCP snooping device (in IRF mode)
display dhcp-snooping packet statistics
[ chassis chassis-number slot slot-number ]
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Display information about trusted ports
display dhcp-snooping trust [ | { begin |
exclude | include } regular-expression ]
Available in any view
Display the DHCP snooping entry file
information
display dhcp-snooping binding database
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Clear DHCP snooping entries reset dhcp-snooping { all | ip ip-address } Available in user view
Clear DHCP packet statistics on the
DHCP snooping device (in standalone
mode)
reset dhcp-snooping packet statistics
[ slot slot-number ]
Available in user view
Clear DHCP packet statistics on the
DHCP snooping device (in IRF mode) reset dhcp-snooping packet statistics
[ chassis chassis-number slot slot-number ] Available in user view