2-2Before using TFTP, the administrator needs to configure IP addresses for the TFTP client and server,and make sure that there is a reachable route between the TFTP client and server.When the device serves as the TFTP client, you need to perform the following configuration:Table 2-1 Configuration when the device serves as the TFTP clientDevice Configuration RemarksDevice (TFTP client)z Configure the IP address and routing function,and ensure that the route between the deviceand the TFTP server is available.z Use the tftp command to establish a connectionto the remote TFTP server to upload/downloadfiles to/from the TFTP server—PC (TFTP server) Enable TFTP server on the PC, and configure theTFTP working directory. —Configuring the TFTP ClientWhen a device acts as a TFTP client, you can upload a file on the device to a TFTP server anddownload a file from the TFTP server to the local device. You can use either of the following ways todownload a file:z Normal download: The device writes the obtained file to the storage medium directly. In this way, ifyou use a filename that exists in the directory, the original system file will be overwritten and if filedownload fails (for example, due to network disconnection), the device cannot start up normallybecause the original system file has been deleted.z Secure download: The device saves the obtained file to its memory and does not write it to thestorage medium until the whole file is obtained. In this way, if file download fails (for example, dueto network disconnection), the device can still start up because the original system file is notoverwritten. This mode is more secure but consumes more memory.You are recommended to use the secure mode or, if you use the normal mode, specify a filename notexisting in the current directory as the target filename when downloading the startup file or the startupconfiguration file.Source address binding means to configure an IP address on a stable interface such as a loopbackinterface, and then use this IP address as the source IP address of a TFTP connection. The sourceaddress binding function simplifies the configuration of ACL rules and security policies. You just need tospecify the source or destination address argument in an ACL rule as this address to filter inbound andoutbound packets on the device, ignoring the difference between interface IP addresses as well as theaffect of interface statuses. You can configure the source address by configuring the source interface orsource IP address. The primary IP address configured on the source interface is the source address ofthe transmitted packets. The source address of the transmitted packets is selected following theserules:z If no source address of the TFTP client is specified, a device uses the IP address of the interfacedetermined by the matched route as the source IP address to communicate with a TFTP server.z If the source address is specified with the tftp client source or tftp command, this source addressis adopted.
