1-3
Figure 1-2
Work flow of automatic configuration
Obtaining the IP Address of an Interface and Related Information Through DHCP
Obtaining an IP address
When a device starts up without loading the configuration file, the system automatically configures the
first active interface of the device as obtaining its IP address through DHCP. The device broadcasts a
DHCP request through this interface. The Option 55 field specifies the information (for example, the
configuration file name, domain name and IP address of the TFTP server and DNS server needed for
obtaining the automatic configuration files) that the device can obtain from the DHCP server.
Upon successfully obtaining its IP address through DHCP, the device resolves the Option 67 (or the file
field, configuration file name) field, Option 66 (domain name of the TFTP server) field, Option 150 (IP
address of the TFTP server) field and Option 6 (IP address of the DNS server) field. If failing to obtain its
IP address, the device removes the temporary configuration and starts up without loading the
configuration file.
