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Specifying a DHCP
Client Identifier
Downloading a
Configuration File
Referenced by a DHCP
Server
Automatic Installation of Operation Code and Configuration Settings
DHCP servers index their database of address bindings using the client's Media
Access Control (MAC) Address or a unique client identifier. The client identifier 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.
DHCP client Identifier (Option 60) is used by DHCP clients to specify their unique
identifier. The client identifier is optional and can be specified while configuring
DHCP on the primary network interface. DHCP Option 60 is disabled by default.
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 (vendor-class-identifier), 66
(tftp-server-name) and 67 (bootfile-name) statements can be added to the server
daemon's configuration file as described in the following section.
If the DHCP server has an index entry for a switch requesting service, it should reply
with the TFTP server name and boot file name. Note that the vendor class identifier
can be formatted in either text or hexadecimal, but the format used by both the
client and server must be the same.
Console(config)#interface vlan 2
Console(config-if)#ip dhcp client class-id hex 0000e8666572
Console(config-if)#
Information passed on to the switch from a DHCP server may also include a
configuration file to be downloaded and the TFTP servers where that file can be
accessed. If the Factory Default Configuration file is used to provision the switch at
startup, in addition to requesting IP configuration settings from the DHCP server, it
will also ask for the name of a bootup configuration file and TFTP servers where
that file is stored.
If the switch receives information that allows it to download the remote bootup file,
it will save this file to a local buffer, and then restart the provision process.
Note the following DHCP client behavior:
◆
The bootup configuration file received from a TFTP server is stored on the
switch with the original file name. If this file name already exists in the switch,
the file is overwritten.
◆
If the name of the bootup configuration file is the same as the Factory Default
Configuration file, the download procedure will be terminated, and the switch
will not send any further DHCP client requests.
Chapter 1
– 65 –
| Initial Switch Configuration
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