How Automatic Configuration Works - 3Com 4210 9-Port Configuration Manual

How Automatic Configuration Works

Figure 5-1 Network diagram for automatic configuration
The Switch 4210 supports automatic configuration. The working process is as follows:
1) As shown in the above figure, when the switch starts up, it automatically configures the VLAN
interface of the default VLAN (in UP state) as a DHCP client. The DHCP client broadcasts a DHCP
request. The Option 55 in the request specifies the information the device needs, such as a
configuration file name and a TFTP server address.
2) From the reply returned by the DHCP server, the switch obtains its IP address, a configuration file
name (Option 67), the domain name (Option 66) or IP address (Option 150) of a TFTP server that
keeps the configuration file.
3) The switch obtains the configuration file from the TFTP server as follows:
The switch first requests the domain name corresponding to its IP address from the DNS server
and takes the domain name as a configuration file name to get the configuration file from the TFTP
server.
If the switch fails to obtain the domain name from the DNS server, it requests the TFTP server for
an intermediate file named netdesc.cfg. If the file contains the host name corresponding to the
switch's IP address, the switch acquires the configuration file corresponding to the host name from
the TFTP server. (For example, if the host name is switch1, the corresponding configuration file
name is switch1.cfg.)
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