H3C S5100-SI Series Operation Manual page 403

Operation Manual – DHCP
H3C S5100-SI/EI Series Ethernet Switches
Figure 1-2 DHCP packet format
The fields are described as follows:
op: Operation types of DHCP packets, 1 for request packets and 2 for response
packets.
htype, hlen: Hardware address type and length of the DHCP client.
hops: Number of DHCP relay agents which a DHCP packet passes. For each
DHCP relay agent that the DHCP request packet passes, the field value increases
by 1.
xid: Random number that the client selects when it initiates a request. The number
is used to identify an address-requesting process.
secs: Elapsed time after the DHCP client initiates a DHCP request.
flags: The first bit is the broadcast response flag bit, used to identify that the DHCP
response packet is a unicast (set to 0) or broadcast (set to 1). Other bits are
reserved.
ciaddr: IP address of a DHCP client.
yiaddr: IP address that the DHCP server assigns to a client.
siaddr: IP address of the DHCP server.
giaddr: IP address of the first DHCP relay agent that the DHCP client passes after
it sent the request packet.
chaddr: Hardware address of the DHCP client.
sname: Name of the DHCP server.
file: Path and name of the boot configuration file that the DHCP server specifies for
the DHCP client.
option: Optional variable-length fields, including packet type, valid lease time, IP
address of a DNS server, and IP address of the WINS server.
1-4
Chapter 1 DHCP Overview