How to set up a new router?

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1. Router startup initial sequence

When the router is initialized, it does the following:

(1) Perform power-on self-test from ROM to check the basic operation of CPU, memory and interface circuits.

(2) Boot from ROM and download the operating system to main memory.

(3) The boot operating system is predetermined by the boot configuration register and downloaded from FLASH or the network, and the boot system command of the configuration file determines its exact location.

(4) The operating system is downloaded to the low-address memory. After downloading, the operating system determines the working hardware and software parts of the router and displays the results on the screen.

(5) The configuration file stored in NVRAM is loaded into the main memory and executed to configure and start the routing process, provide interface addresses, and set media characteristics. If there is a valid configuration file in NVRAM, the setup session mode is entered.

(6) Then enter the system configuration session to display configuration information, such as the configuration information of each interface.

2. Setup Session

When there is no valid configuration file in NVRAM, the router will automatically enter the Setup session mode. You can also type Setup in the command line to configure it later.

The Setup command is an interactive command. Each question has a default configuration. If you want to use the default configuration, just press Enter. If the system has been configured, the current configuration value will be displayed. If it is the first configuration, the factory settings will be displayed. When the screen displays "------ More ------", press the space bar to continue;

To exit from Setup, just type Ctrl-C.

1. Setup main parameters:

Configure its general parameters, including:

 Hostname: hostname
 Privileged password: enable password
 Virtual terminal password: virtual terminal password
 SNMP Network Management
 IP: IP
 IGRP Routing Protocol: IGRP Routing
 RIP Routing Protocol: RIP Routing
 DECnet: DECnet. etc. 
 
 The settings of Console secret and password are as follows:
 enable secret
 enable password
 Setting the password of Virtual Terminor:
 Line vty
 Password
 Host name settings:
 Hostname

2. Setup interface parameters:

Set interface parameters, such as Ethernet port, TokenRing port, synchronous port, asynchronous port, etc. Including IP address, subnet mask, TokengRing rate, etc.

3. Setup Description: After setting the above parameters, the command prompts whether to use the above configuration. If the answer is "YES", the system will store the above configuration parameters and the system can be used.

4. Setup related commands:

 Show config
 write memory
 write erase
 reload
 setup

5. Recovering the lost password of the router

The following methods can be used to restore:

enable secret password (for version 10.3(2) or later)

 enable password
 console password

By modifying the Configuration Register (factory value is 0x2102), the router ignores PASSWORD. Then you can enter the router and see the enable password and console password, but the enable secret password is encrypted and can only be replaced. The configuration register value that can be entered is 0x142.

 Running a password recovery may cause the system to be down for an hour and a half;
 Connect the console terminal to the console port of the router and make sure the terminal is set to 9600bps, 8
 Data bit, No parity, 1 stop bit;
 show version displays Configuration Register 0x2102.
 · Turn the computer off and then on again, press "Ctrl+ Break" to enter the ROM MONITOR state, the prompt is " > ";
 Type " > o/r 0x142" to modify Configuration Register to 0x142. You can ignore the original
 password;
 Type " > initialize" to initialize the router. After a while, the router will display the following prompt
 :
 "system configuration Diaglog…"
 Enter "NO"
  Prompt "Press RETURN to get started!" ,Press "Enter"
 Enter privileged mode
 Router > enable
 Router#show startup-config
 In this way, you can get the password (enable & console password)
 Change password
 "Router#config ter"
 "Router(config)# enable secret cisco"
 "Router(config)# enable password cisco1"
 "Router(config)# line con 0"
 "Router(config)# password cisco"
 "Router(config)# config-register 0x2102"
 "ctrl + Z"
 "Router#copy running-config startup-config"
 "reload"
 Enter the privileged user with password cisco.

3. Router Configuration

(1) Router mode

In Cisco routers, the command interpreter is called EXEC. EXEC interprets the commands typed by the user and performs the corresponding operations. You must log in to the router before entering the EXEC command. For security reasons, EXEC sets two access rights: user level and privileged level. The commands that can be executed at the user level are a subset of the privileged level commands.

At the privileged level, you can use commands such as configuration, interface, subinterface, line, router, and router-map.

(2) Configuration mode Use the Config command to enter configuration mode. After entering this mode, EXEC prompts the user for available configuration methods, such as terminal, NVRAM, and network. The default is terminal mode.

(3) IP routing protocol mode: In the configuration mode, enter the Router command to enter the IP routing protocol mode. The optional routing protocols generally include: bgp, egp, igrp, eigrp, rip and other dynamic routing and static routing.

(4) Interface configuration mode can set many features on each port. Interface configuration commands modify the operation of Ethernet, Token Ring, FDDI or synchronous and asynchronous ports.

(5) Password Configuration Passwords can be used to restrict access to the router. Passwords can be set to specific lines or privileged EXEC mode. Line console 0 command sets the console terminal password Line vty 0 command sets the Telnet virtual terminal password Enable-password command sets privileged EXEC access rights

(6) In configuration mode, the router name is hostname, such as: hostname RouterA

4. User Help Tips

1. Type ? at the user prompt to list common commands, usually the following commands:

 connect opens a middle connection
 disconnect Close an existing telnet session
 enable Enter privilege level
 exit Exit EXEC
 help Interactive help system description
 lock Terminal lock
 login Log in as a specific user
 logout Exit EXEC
 ping sends echo information
 resume Resume an active telnet connection
 show Displays the running system information
 systat displays information about the running system
 telnet Open a telnet connection
 terminal Set terminal line parameters
 where lists active telnet connections

2. Context-sensitive help Context-sensitive help includes:

• Symbol conversion: prompt when there is an error in typing a command;
• Keyword completion: just type part of the command word;
• Command memory: Use " " to call up previous commands;
• Command prompt: When you cannot remember the command completely, you can use "?" instead.