3.5 Router Power-up and Boot Process
When the router is shipped, it comes with the latest version of JUNOS software loaded on nonrotating flash memory. Additional copies are provided on the hard disk and on a PC card that is shipped with the router. When the router is powered-up for the first time, it looks for the software in the following sequence:
- PC card, if installed
- Flash memory
- Hard disk
The first copy that it encounters is the one it will use. Therefore, it is important to not insert a PC card if you want to boot from flash memory, for example.
It is a good idea to keep the original PC card (as well as any copies of future releases) in a safe place in case the file system becomes corrupted or unstable. This will allow you to revert to the original version by rebooting the router with the PC card in place.
To power-up the router, perform the following steps:
Power-up the management device that is connected to the console, auxiliary, or management Ethernet port on the routing engine.
Turn the power on for each power supply.
Check the power supply OK LEDs and the output to the management device to ensure that the router booted properly.
If nothing is plugged into the management Ethernet interface, a RED alarm will be generated. Plug in any device cable with an RJ-45 connector to prevent this alarm.
Other visible activity to check at startup includes the following:
Craft interface displays, such as Starting routing engine, Starting PFE, and Starting Card
FPC LEDs, which blink green until testing is complete (if all tests pass, the lights should be solid green)
Alarm LEDs, as appropriate
PIC LEDs, which remain off unless the interfaces have been configured
3.5.1 Configuring the Router
During the initial configuration of the router, you will need to configure the following:
A password for user ROOT. This can be set in three different ways:
Plain text (not logged, if logging is enabled): root@router# set system root-authentication plain- text-password password (password is prompted on a separate line)
Pre-encrypted: root@router# set system root-authentication encrypted-password password
Secure shell (SSH) key (on domestic U.S. systems only): root@router# set system root-authentication ssh-rsa key
A hostname for the router:  root@router# setsystem host-name name
The domain name:
 root@router# set system domain-name domain
The IP address and subnet mask of the management Ethernet port:
 root@router# set interfaces fxp0 unit 0 family inet address ip-address/prefix-length
The default route:
 root@router# set system backup-router gateway-address root@router# set routing-options static route default nexthop gateway-address retain no-advertise
The domain name server (DNS) IP address:
 root@router# set system name-server dns-address
At least one NON-ROOT user:
 root@router# set system login user username class class authentication plain-text-password
It is vitally important to configure a NON-ROOT user, as ROOT cannot Telnet into the router!
After configuring the preceding, save your changes:
 root@router# commit