Introduction To Dhcp Accounting - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide
DHCPOFFER/
Discard
DHCPOFFER,
Figure 9-2 DHCP client state transit

9.2.3 Introduction to DHCP Accounting

DHCP accounting enables a DHCP server to notify the RADIUS server of the start or
end of accounting when assigning or reclaiming a lease. The cooperation of the DHCP
server and RADIUS server implements the network accounting function, and at the
same time improves the network security to a certain degree.
I. Structure of the DHCP accounting packet
The interactive operations between the DHCP server and the RADIUS server are
based on two types of packets: accounting start request and accounting stop request.
The two types of packets have the similar structure, and the only difference lies in the
Attributes field. The following figure illustrates the packet structure:
DHCPNAK/
Discard offer
DHCPACK
(not accept.)/
Send DECLINE
send DHCPREQUEST
REQUESTING
DHCPACK/
Record lease, set
timers T1, T2
BOUND
DHCPACK,
DHCPNAK/
T1 expires/
Discard
Send DHCPREQUEST
to leasing server
3Com Corporation
INIT
-/Send DHCPDISCOVER
SELECTING
Select offer/
DHCPACK/
Record lease, set
timers T1,T2
DHCPACK/
Record lease, set
timers T1, T2
RENEWING
9-5
Chapter 9 DHCP Configuration
DHCPNAK,
Lease expired/
Halt network
DHCPOFFER
/Collect
replies
REBINDING
T2 expires/
Broadcast
DHCPREQUEST
DHCPNAK/
Halt network