Chapter 24
| DHCP Commands
DHCP Client
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◆
This command is used to identify the vendor class and configuration of the
switch to the DHCP server, which then uses this information to decide on
how to service the client or the type of information to return.
◆
The general framework for this DHCP option is set out in RFC 2132
(Option 60). This information is used to convey configuration settings or
other identification information about a client, but the specific string to use
should be supplied by your service provider or network administrator.
Options 60, 66 and 67 statements can be added to the server daemon’s
configuration file.
◆
By default, DHCP option 66/67 parameters are not carried in a DHCP
server reply. To ask for a DHCP reply with option 66/67 information, the
DHCP client request sent by this switch includes a “parameter request list”
asking for this information. Besides, the client request also includes a
“vendor class identifier” set by the
ip dhcp client class-id
command that
allows the DHCP server to identify the device, and select the appropriate
configuration file for download. This information is included in Option 55
and 124.
◆
The server should reply with Option 66 attributes, including the TFTP
server name and boot file name.
◆
Note that the vendor class identifier can be formatted in either text or
hexadecimal using the
ip dhcp client class-id
command, but the format
used by both the client and server must be the same.
Example
Console(config)#interface vlan 2
Console(config-if)#ip dhcp client class-id hex 0000e8666572
Console(config-if)#
Table 121: Options 60, 66 and 67 Statements
Option
Statement
Keyword
Parameter
60
vendor-class-identifier
a string indicating the vendor class identifier
66
tftp-server-name
a string indicating the tftp server name
67
bootfile-name
a string indicating the bootfile name
Table 122: Options 55 and 124 Statements
Option
Statement
Keyword
Parameter
55
dhcp-parameter-request-list a list of parameters, separated by ','
124
vendor-class-identifier
a string indicating the vendor class identifier