Configuring Ip Address Detecting; Configuring Dhcp Accounting Functions; Introduction To Dhcp Accounting; Dhcp Accounting Fundamentals - 3Com 4210 9-Port Configuration Manual

Enable the unauthorized DHCP server
detecting function
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...
Enter system view
Specify the number of ping
packets
Configure a timeout waiting for
ping responses

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.
To do...
Use the command...
system-view
dhcp server ping packets
number
dhcp server ping timeout
milliseconds
Use the command...
dhcp server detect
2-23
Remarks
Required
Disabled by default.
Remarks
—
Optional
Two ping packets by default.
Optional
500 ms by default.