Dhcp options, Overview, Introduction to dhcp options – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
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siaddr: Server IP address, from which the client obtained configuration parameters.
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giaddr: IP address of the first relay agent a request message traveled.
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chaddr: Client hardware address.
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sname: Server host name, from which the client obtained configuration parameters.
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file: Bootfile name and path information, defined by the server to the client.
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options: Optional parameters field that is variable in length, which includes the message type,
lease, domain name server IP address, and WINS IP address.
DHCP options
Overview
DHCP uses the same message format as BOOTP, but DHCP uses the Option field to carry information for
dynamic address allocation and to provide additional configuration information to clients.
shows the DHCP option format.
Figure 9 DHCP option format
Introduction to DHCP options
Common DHCP options:
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Option 3: Router option. It specifies the gateway address.
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Option 6: DNS server option. It specifies the DNS server’s IP address.
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Option 33: Static route option. It specifies a list of classful static routes (the destination addresses in
these static routes are classful) that a client should add to its routing table. If both Option 33 and
Option 121 exist, Option 33 is ignored.
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Option 51: IP address lease option.
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Option 53: DHCP message type option. It identifies the type of the DHCP message.
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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.
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Option 66: TFTP server name option. It specifies a TFTP server to be assigned to the client.
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Option 67: Bootfile name option. It specifies the bootfile name to be assigned to the client.
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Option 121: Classless route option. It specifies a list of classless static routes (the destination
addresses in these static routes are classless) that the requesting client should add to its routing table.
If both Option 33 and Option 121 exist, Option 33 is ignored.
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Option 150: TFTP server IP address option. It specifies the TFTP server IP address to be assigned to
the client.
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