1-2name of the TFTP server from a DHCP response, the device can also resolve the domain name ofthe TFTP server to the IP address of the TFTP server through the DNS server.If the DHCP server, TFTP server, DNS server, and the device that performs automatic configuration arenot in the same segment, you need to configure DHCP relay on a device working as a gateway.How Automatic Configuration WorksBasically, automatic configuration works in the following ways:1) When a device starts up without loading any configuration file, the system sets the first activeinterface (if an active Layer 2 Ethernet interface exists, this first interface is a virtual interfacecorresponding with the default VLAN) as the DHCP client to request from the DHCP server forparameters, such as an IP address and name of a TFTP server, IP address of a DNS server, andthe configuration file name.2) After getting related parameters, the device will send a TFTP request to obtain the configuration filefrom the specified TFTP server for system initialization. If the client cannot get such parameters, itperforms system initialization without loading any configuration file.z To implement auto-configuration, you need to configure some parameters on the DHCP server,DNS server and TFTP server, but you do not need to perform any configuration on the device thatstarts up without loading any configuration file. The configuration mode depends on the devicemodel; it is omitted here.z If you need to use the automatic configuration function, you are recommended to connect only theinterfaces needed in automatic configuration to the network.Work Flow of Automatic ConfigurationThe work flow of automatic configuration is as shown in Figure 1-2.
