Panasonic DP-8020E, Руководство по обслуживанию

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455
SEP 2006
Ver. 1.0
DP-8020E/8020P/8016P
Several options have been defined so far. One particular option - the "DHCP message type" option - must
be included in every DHCP message. This option defines the "type" of the DHCP message.
Additional options may be allowed, required, or not allowed, depending on the DHCP message type.
For more detailed information, please refer to RFC2131 document available from the following URL:
http://www.ietf.org/rfc.html.
T1 expires/
Send
DHCPREQUEST
to leasing server
INITIALIZATION
INITIALIZE/
REBOOT
REBOOTING
SELECTING
REBINDING REQUESTING
BOUND
RENEWING
-/Send DHCPREQUES
DHCPNAK/
Restart
DHCPOFFER/
Discard
DHCPACK/
Record lease, set
timers T1, T2
T1 expires/
Send DHCPREQUEST
to leasing server
DHCPNAK/
Discard offer
DHCPACK
(not accepted)/
Send DHCPDECLINE
DHCPOFFER/
Collect replies
-/Send DHCPDISCOVER
DHCPNAK, Lease expired/
Halt network
Select offer/
send DHCPREQUEST
DHCPACK/
Record lease, set
/timers T1,T2
DHCPACK/
Record lease, set
/timers T1,T2
DHCPACK/
Record lease, set
timers T1, T2
T2 expires/
Broadcast
DHCPREQUEST
DHCPNAK/
Halt network
State-transition diagram for DHCP clients
The client maintains two times, T1 and T2, that specify the times at which the client tries to extend its lease on its
network address. T1 is the time at which the client enters the RENEWING state and attempts to contact the server
that originally issued the client’s network address. T2 is the time at which the client enters the REBINDING state and
attempts to contact any server. T1 MUST be earlier than T2, which, in turn, MUST be earlier than the time at which
the client’s lease will expire.
To avoid the need for synchronized clocks, T1 and T2 are expressed in options as relative times.