Dhcp Options; Dhcp Options Overview; Introduction To Dhcp Options; Self-Defined Options - H3C S7500E Series Operation Manual

Operation Manual – DHCP
H3C S7500E Series Ethernet Switches

1.4 DHCP Options

1.4.1 DHCP Options Overview

The DHCP message adopts the same format as the Bootstrap Protocol (BOOTP)
message for compatibility, but differs from it in the option field, which identifies new
features for DHCP.
DHCP uses the option field in DHCP messages to carry control information and
network configuration parameters, implementing dynamic address allocation and
providing more network configuration information for clients.
Figure 1-4
Figure 1-4 DHCP option format

1.4.2 Introduction to DHCP Options

The common DHCP options are:
Option 6: DNS server option. It specifies the DNS server IP address to be
assigned to the client.
Option 51: IP address lease option.
Option 53: DHCP message type option. It identifies the type of the DHCP
message.
Option 55: Parameter request list option. It is used by a DHCP client to request
specified configuration parameters. The option contains values that correspond to
the parameters requested by the client.
Option 66: TFTP server name option. It specifies a TFTP server to be assigned to
the client.
Option 67: Bootfile name option. It specifies the bootfile name to be assigned to
the client.
Option 150: TFTP server IP address option. It specifies the TFTP server IP
address to be assigned to the client.
For more information about DHCP options, refer to RFC 2132.

1.4.3 Self-Defined Options

Some options have no unified definitions in RFC 2132. The formats of some
self-defined options are introduced as follows.
shows the DHCP option format.
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Chapter 1 DHCP Overview