Supported Platforms
Understanding Autoinstallation of Configuration Files
Autoinstallation is the automatic configuration of a device over the network from a preexisting configuration file that you create and store on a configuration server—typically a Trivial File Transfer Protocol (TFTP) server. You can use autoinstallation to configure new devices automatically and to deploy multiple devices from a central location in the network.
You enable autoinstallation so that the switches in your network implement autoinstallation when they are powered on. To configure autoinstallation, you specify a configuration server, an autoinstallation interface, and a protocol for IP address acquisition.
This topic describes:
Typical Uses for Autoinstallation
Typical uses for autoinstallation of the software include:
- To deploy and update multiple devices from a central location in the network.
- To update a device—Autoinstallation occurs when a device that has been manually configured for autoinstallation is powered on.
Autoinstallation Configuration Files and IP Addresses
For the autoinstallation process to work, you must store one or more host-specific or default configuration files on a configuration server in the network and have a service available—typically Dynamic Host Configuration Protocol (DHCP)—to assign an IP address to the switch.
You can set up the following configuration files for autoinstallation on the switch:
- network.conf—Default configuration file for autoinstallation, in which you specify IP addresses and associated hostnames for devices on the network.
- switch.conf—Default configuration file for autoinstallation with a minimum configuration sufficient for you to telnet to the device and configure it manually.
- hostname.conf—Host-specific configuration file for autoinstallation on a device that contains all the configuration information necessary for the switch. In the filename, hostname is replaced with the hostname assigned to the switch.
If the server with the autoinstallation configuration file is not on the same LAN segment as the new device, or if a specific device is required by the network, you must configure an intermediate device directly attached to the new switch, through which the new switch can send TFTP, Boot Protocol (BOOTP), and Domain Name System (DNS) requests. In this case, you specify the IP address of the intermediate device as the location to receive TFTP requests for autoinstallation.
Typical Autoinstallation Process on a New Switch
When the switch configured for autoinstallation is powered on, it performs the following autoinstallation tasks:
- The switch sends out DHCP or BOOTP requests on each connected
interface simultaneously to obtain an IP address.
If a DHCP server responds to these requests, it provides the switch with some or all of the following information:
- An IP address and subnet mask for the autoinstallation interface.
- The location of the (typically) TFTP server, Hypertext Transfer Protocol (HTTP) server, or FTP server on which the configuration file is stored.
- The name of the configuration file to be requested from the TFTP server.
- The IP address or hostname of the TFTP server.
If the DHCP server provides the server’s hostname, a DNS server must be available on the network to resolve the name to an IP address.
- The IP address of an intermediate device if the configuration server is on a different LAN segment from the switch.
- After the switch acquires an IP address, the autoinstallation
process on the switch attempts to download a configuration file in
the following ways:
- If the DHCP server specifies the host-specific configuration file hostname.conf, the switch uses that filename in the TFTP server request. The autoinstallation process on the new switch makes three unicast TFTP requests for hostname.conf. If these attempts fail, the switch broadcasts three requests to any available TFTP server for the file.
- If the switch does not locate a hostname.conf file, the autoinstallation process sends three unicast TFTP requests for a network.conf file that contains the switch’s hostname-to-IP-address mapping information. If these attempts fail, the switch broadcasts three requests to any available TFTP server for the file.
- If the switch fails to find a network.conf file that contains a hostname entry for the switch, the autoinstallation process sends out a DNS request and attempts to resolve the switch's IP address to a hostname.
- If the switch determines its hostname, it sends a TFTP request for the hostname.conf file.
- If the switch is unable to map its IP address to a hostname, it sends TFTP requests for the default configuration file switch.conf. The TFTP request procedure is the same as for the network.conf file.
- After the switch locates a configuration file on a TFTP server, the autoinstallation process downloads the file, installs the file on the switch, and commits the configuration.
