TP-Link T3700G-28TQ User Manual page 184

op：Message type, '1' = BOOT-REQUEST, '2' = BOOT-REPLY.
1)
htype：Hardware address type, '1' for ethernet.
2)
hlen：Hardware address length, '6' for ethernet.
3)
hops： Clients set this field to zero and broadcast the DHCP-REQUEST message , optionally
4)
used by relay-agents when booting via a relay-agent.
xid： Transaction ID, a random number chosen by the client, used by the client and server to
5)
associate messages.
secs：Filled in by client, seconds elapsed since client started trying to boot.
6)
flags： A client that cannot receive unicast IP datagrams until its protocol software has been
7)
configured with an IP address should set the first bit in the 'flags' field to 1 in any
DHCP-DISCOVER or DHCP-REQUEST message that client sends. A client that can receive
unicast IP datagrams before its protocol software has been configured should clear the
first bit to 0. A server or relay agent sending or relaying a DHCP message directly to a
DHCP client should examine the first bit in the 'flags' field. If this bit is set to 1, the DHCP
message should be sent as an IP broadcast and if the bit is cleared to 0, the message
should be sent as an IP unicast. The remaining bits of the flags field are reserved for future
use and must be set to zero by clients and ignored by servers and relay agents.
ciaddr：Client IP address, filled in by client in DHCPREQUEST when verifying previously
8)
allocated configuration parameters.
yiaddr：'your' (client) IP address, configuration parameters allocated to the client by DHCP
9)
server.
10) siaddr：IP address of next server to use in bootstrap, returned in DHCPOFFER, DHCPACK
and DHCPNAK by server.
11) giaddr：Relay agent IP address, used in booting via a relay-agent.
12) chaddr：Client hardware address.
13) sname：Optional server host name, null terminated string.
Figure 10-8 The Format of DHCP Message
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