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Initially Configuring the MX240 Router

The T320 router is shipped with Junos OS preinstalled and ready to be configured when the T320 router is powered on. There are three copies of the software: one on a CompactFlash card in the Routing Engine, one on a rotating hard disk in the Routing Engine, and one on a USB flash drive that can be inserted into the slot in the Routing Engine faceplate.

When the router boots, it first attempts to start the image on the USB flash drive. If a USB flash drive is not inserted into the Routing Engine or the attempt otherwise fails, the router next tries the CompactFlash card (if installed), and finally the hard disk.

You configure the router by issuing Junos OS command-line interface (CLI) commands, either on a console device attached to the CONSOLE port on the Routing Engine, or over a telnet connection to a network connected to the ETHERNET port on the Routing Engine.

Gather the following information before configuring the router:

  • Name the router will use on the network

  • Domain name the router will use

  • IP address and prefix length information for the Ethernet interface

  • IP address of a default router

  • IP address of a DNS server

  • Password for the root user

This procedure connects the router to the network but does not enable it to forward traffic. For complete information about enabling the router to forward traffic, including examples, see the Junos OS configuration guides.

To configure the software:

  1. Verify that the router is powered on.
  2. Log in as the “root” user. There is no password.
  3. Start the CLI.
  4. Enter configuration mode.
  5. Configure the name of the router. If the name includes spaces, enclose the name in quotation marks (“ ”).
  6. Create a management console user account.
  7. Set the user account class to super-user.
  8. Configure the router’s domain name.
  9. Configure the IP address and prefix length for the router’s Ethernet interface.
  10. Configure the IP address of a backup router, which is used only while the routing protocol is not running.
  11. Configure the IP address of a DNS server.
  12. Set the root authentication password by entering either a clear-text password, an encrypted password, or an SSH public key string (DSA or RSA).




  13. (Optional) Configure the static routes to remote subnets with access to the management port. Access to the management port is limited to the local subnet. To access the management port from a remote subnet, you need to add a static route to that subnet within the routing table. For more information about static routes, see the Junos OS Administration Library for Routing Devices.
  14. Configure the telnet service at the [edit system services] hierarchy level.
  15. (Optional) Display the configuration to verify that it is correct.
  16. Commit the configuration to activate it on the router.
  17. (Optional) Configure additional properties by adding the necessary configuration statements. Then commit the changes to activate them on the router.
  18. When you have finished configuring the router, exit configuration mode.

To reinstall Junos OS, you boot the router from the removable media. Do not insert the removable media during normal operations. The router does not operate normally when it is booted from the removable media.

When the router boots from the storage media (removable media, CompactFlash card, or hard disk) it expands its search in the /config directory of the routing platform for the following files in the following order: juniper.conf (the main configuration file), rescue.conf (the rescue configuration file), and juniper.conf.1 (the first rollback configuration file). When the search finds the first configuration file that can be loaded properly, the file loads and the search ends. If none of the file can be loaded properly, the routing platform does not function properly. If the router boots from an alternate boot device, Junos OS displays a message indication this when you log in to the router.