H3C Technologies H3C S3100 Series Switches - Manual (Page 524)

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To do… Use the command… Remarks
Enable the unauthorized DHCP server
detecting function
dhcp server detect
Required
Disabled by default.
With the unauthorized DHCP server detection enabled, the relay agent will log all DHCP servers,
including authorized ones, and each server is recorded only once. The administrator needs to find
unauthorized DHCP servers from the system log information.
Configuring IP Address Detecting
To avoid IP address conflicts caused by assigning the same IP address to multiple DHCP clients
simultaneously, you can configure a DHCP server to detect an IP address before it assigns the address
to a DHCP client.
The DHCP server pings the IP address to be assigned using ICMP. If the server gets a response within
the specified period, the server will ping another IP address; otherwise, the server will ping the IP
addresses once again until the specified number of ping packets are sent. If still no response, the server
will assign the IP address to the requesting client (The DHCP client probes the IP address by sending
gratuitous ARP packets).
Follow these steps to configure IP address detecting:
To do… Use the command… Remarks
Enter system view system-view —
Specify the number of ping
packets dhcp server ping packets
number Optional
Two ping packets by default.
Configure a timeout waiting for
ping responses dhcp server ping timeout
milliseconds
Optional
500 ms by default.
Configuring DHCP Accounting Functions
Introduction to DHCP Accounting
DHCP accounting allows a DHCP server to notify the RADIUS server of the start/end of accounting
when it assigns/releases a lease. The cooperation of DHCP server and RADIUS server implements the
network accounting function and ensures network security at the same time.
DHCP Accounting Fundamentals
After you complete AAA and RADIUS configuration on a switch with the DHCP server function enabled,
the DHCP server acts as a RADIUS client. For the authentication process of the DHCP server acting as
a RADIUS client, refer to AAA Operation in this manual. The following describes only the accounting
interaction between DHCP server and RADIUS server.