Router Basics | Modular and Fixed Routers

 Configuration of a Router 

The router for the first time is configured through the CONSOLE port.COM port of a PC is connected to the console port of the router with a console cable by using a transceiver. The router is accessible by a tool. In Windows, it is called HYPER TERMINAL. As soon as the router is powered on and accessed, the following things happen,

                              

In Setup mode, there will be a message,

“Would You Like To Enter The Initial Configuration [Y/N]” :

If “Y” then, the initial configuration starts.

If “N” would you like to terminate the auto installation?

Press “RETURN” to get started……You will land on the default prompt of the Router “ ROUTER >”.

Router>_

     Working Modes Of a Router 

        1. User Mode (Default mode)

        2. Privilege or Administrative Mode

        3. Global Configuration Mode

        4. Interface Configuration Mode

        5. Line Configuration Mode

        6. Router Mode

        7. Sub-Interface Mode

1. USER MODE   

Router> is the user mode, I,e the default prompt. It means that whenever a router boots successfully it lands into the user mode. The router cannot be configured from this mode, but it is used for just monitoring purposes.

Router> en

Router #

2. PRIVILEGE MODE 

Router#  It is the administrating mode, we can check whether the settings and configurations made have been implemented or not. Eg. “Router # Sh int e0”. If it is a new router all the interfaces are by default shut down, so the message will be, 

“Ethernet 0 is administratively down, line protocol is down.”

                     The “Clock” Command 

The clock command is used to set the clock of the Router.

Syntax.

Router# clock set hh:mm: ss Day of week   Month   Year

E.g.

Router# clock set 10:35:00 1 April 2023

Note* This is the only configuration that can be done from privilege mode; Every other configuration should be done in global configuration mode only.

Some of the important show commands in privileged mode 

Router#    Sh clock

               Sh int (interface name eg e0)

               Sh history

               Sh memory

               Sh running-config

                      Sh startup-config

To save configuration from RAM TO NVRAM

Router# Copy Running-config Startup-config

                                (or)

Router# Write Memory 

3. Global Configuration Mode 

As the name indicates, it is a global configuration mode I,e. we can configure any interface from this mode, just by entering into the interface mode.

Router# Config t   

Router (Config)#  

To configure Hostname (or) Change of Router name over the network.

Router# conf t

Router (config) # Hostname Tosif         {Press Enter Key}

Tosif (config) # ^Z

To configure the Logging banner.

Router# conf t

Router (config)#Banner Motd #       {Press Enter Key}

=================================

UNAUTHORIZED ACCESS IS PROHIBITED #

=================================

Router (config)#^Z

 Router login/Password Configuration

      Router login:- Set Router login credentials for the different modes of the router. By setting router login credentials you can secure your network. Below are the different modes to secure routers' login from unauthorized access. 

1. Previlege  Password
   
   
2. Virtual Terminal Password
   
   
3. Console Password.
   
   
4.  Auxillary Password

 1. PREVILEGE Password 

Enable Password: - It is the global command that restricts access to the privilege mode, the password is in clear text.

                                    Router (config) # Enable password 123

Enable Secret: - Here the password is in encrypted (MD5) form.

                                               Router (config) #Enable secret Cisco

 2. Virtual Terminal Password 

It establishes a login password on incoming Telnet sessions.

                        

Router # conf t

Router (config) # Line vty 0 4

Router (config-line) # Login

Router (config-line) # password Cisco

Router (config-line) # ^Z

 3. Console Password 

It establishes a login password on the console terminal.

Router #conf t

Router (config) #Line Console 0

Router (config-line) #Login

Router (config-line) #Password Cisco

Router (config-line) #^Z

 4. Auxiliary Password 

It establishes a login password for remote administration.

Router# conf t                         {Press Enter Key}

Router (config) #Line Aux 0     {Press Enter Key}

Router (config-line) #Login       {Press Enter Key}

Router (config-line) #Password Cisco   {Press Enter Key}

Router (config-line) #^Z

 How To Use Aliases Command on Cisco 

            

        Used to create shortcuts for long commands. 

 Examples 

Router (Config)# alias exec c configure terminal

Router (Config)# alias exec s show ip interface brief

Router (Config)# alias exec sr show running-config

Router(config)#alias exec td telnet device

Router(config)#end

Router# t?

telnet terminal test tn3270 trace

         The default aliases are predefined. These default aliases can be disabled with the 

                                                        no alias exec command.

 How To Configure Interfaces 

            

            1. LAN Interface (ETHERNET Port)

         2. WAN Interface (SERIAL Port)

 1. LAN interface Basic (ETHERNET Port) Configuration 

Router (config) #Interface Ethernet 0

Router (config-if) #ip Address 200.150.1.254 255.255.255.0

Router (config-if) #description Link to Internet Router

Router (config-if) #no shutdown

Router (config-if) #^Z (Exit)

Router# Show interface Ethernet0 / Int E0

 1. SERIAL interface Basic (Serial Port) Configuration 

Router (config) #Interface Serial 0

Router (config-if) #Ip Address 150.10.1.1 255.255.0.0

Router (config-if) #description Link to HR Department Switch

Router (config) #clock rate 56000

Router (config-if) # bandwidth 64

Router (config-if) #No shutdown

Router (config-if) #^Z (exit)

 Interpreting the Interface Status 

Router# show int s0

Serial0 is up, Line protocol is up. Is the message if the interface is operational.

Serial0 is up, Line protocol is down… This is if there is any connection problem.

Serial0 is down, Line protocol is down… This is if there is any interface problem.

Serial0 is administratively down, Line protocol is down….. This is if the interface is disabled.

Gigabitethernet0/1 is up, line protocol is up

 The “CDP” (Cisco Discovery Protocol) 

It is a Cisco proprietary protocol called the Cisco Discovery Protocol that gives you a summary of all the directly connected Cisco devices. CDP is an L2 protocol that discovers neighbors regardless of which protocol suite they are running. When a Cisco device boots up, the CDP is loaded by default but can be disabled at the interface level.

* The CDP is limited to the immediate neighbors only…

The summary includes Device Identifier (e.g. Switch configured name or domain name), Port Identifier (e.g. Ethernet 0 and serial 0.), Capabilities list (e.g. The device can act as a source route bridge as well as a router), Platform (e.g. Cisco 2600).

Router# sh cdp neighbor (shows neighboring devices)

Router# sh cdp entry 192.168.10.1 (shows detailed information about this particular neighbor.)

Router# sh cdp interface (shows the details of the interface of the local deceive.)

Router# sh cdp traffic (shows the packet sent, received, lost, etc.)

 

 To Disable CDP…,

Router (config) #no cdp run

Router (config) #int s0

Router (config-if) #no cdp enable

Cisco Discovery Protocol

 

Connected Cisco Devices Using CDP Command

  Backup & Restoring Routers IOS Image 

  Using TFTP (Trivial File Transfer Protocol) 

                                         

TFTP Server allows you to take backup, upload and save your IOS Image and current configuration on it.  TFTP is a software program of 1.3 MB. This should be installed on that TFTP server i.e., (Personnel Computer).

C:\Program files\cisco systems\cisco TFTP

* Note: Always while taking Backup or Restoration TFTP software should execute on that particular computer.

 Backup Sources 

1. Through Telnet Session.

2. Through Telnet Session.

3. Through Auxiliary Port (Remote Session)

 Backup of IOS Image 

===============================================

Steps-

Router#copy flash: tftp

Source filename []?  { Name of IOS Image }

Address or name of remote host []?  { IP Address of the TFTP server }

Destination filename    { Where you want to save your IOS Image }

Done 

=================================================

Router# sh flash:

System flash directory:

File Length   Name/status

  3   33591768 c2900-universalk9-mz.SPA.151-4.M4.bin (IOS Image)

  2   28282    sigdef-category.xml

  1   227537   sigdef-default.xml

[33847587 bytes used, 221896413 available, 255744000 total]

249856K bytes of processor board System flash (Read/Write)

 IOS Image Backup Lab 

Router#copy flash: tftp: 

Source filename []? c2900-universalk9-mz.SPA.151-4.M4.bin

Address or name of remote host []? 10.71.227.3

Destination filename [c2900-universalk9-mz.SPA.151-4.M4.bin]? tosif.txt

Writing c2900-universalk9-mz.SPA.151-4.M4.bin....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[OK - 33591768 bytes]

33591768 bytes copied in 3.713 secs (949904 bytes/sec)

 Backup of Configuration 

=========================================================

Steps:

Router# Copy Startup-config Tftp

Address or name of the remote host [ ]? (Ip address of tftp)

Destination file name [ ]? (Give a name)

Done

=========================================================

 Upgrading IOS Image 

Note: This process can only be done by Console Session.

=========================================================

Steps:

Router# Copy tftp Flash:

Address or name of remote host []?

Source file name []?

Destination file name []?

Erase Flash: before copying [confirm]?

Erasing the Flash file system will remove all files: continue. [Confirm]

Erasing device eeeeeeee….eeeeeee.eee.eeee.ee

Loading!!!!!!!!!!!!!!!!!!!!!!!!!!!!!…….!!!!…….!!!!!!

Done

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 Leased line WAN Setup 

=============================================

Case 1: The distance between the locations is greater than 5 Km.
Requirements

A pair of Routers, a Leased line, pair of leased line modems V.35,
Pair of G.703 Modem.

Case 2: The distance between the two locations is less than 5 km.
Requirements

A pair of Routers, a Leased line, and pair of leased line modems

=========================================================

 Leased Line Setup(> 5K.M.)  

Leased Line Setup(> 5K.M.)

 Leased Line Setup(< 5K.M.)  

Leased Line Setup(< 5K.M.)