All posts tagged cisco

Good evening friends, today we will see how to enable IPv6 on a cisco router with cisco ios. To know what is IPv6, go here. Enabling IPv6 routing on a cisco router is pretty easy and involves only a few commands.

First of all, we have to enable the router to pass IPv6 traffic. In global configuration mode of the router, type command “ipv6 unicast-routing”. Then go to the specific interface on which you want to configure IPv6 addressing by typing command “interface <type> <number>”  as shown below.  Type command “ipv6 enable”.

ipv6 on a cisco router

Now let’s check whether IPv6 is enabled or not on our specified interface. Go back to Privileged Exec Mode  and type command “show ipv6  interface ethernet1/0″. To know about different modes on Cisco IOS, go here. Now when we type the above command, we can see that our device has been assigned a IPv6 address as shown below.

ipv6 on a cisco router


AEtherchannel is the port link aggregation technology invented by a company named Kalpana. This company was acquired by Cisco systems in 1994.  Etherchannel allows us to group several ( practically eight ) physical Ethernet links on a Cisco switch into one logical link. Advantages of etherchannel include increased bandwidth and fault tolerance. For example, when we group eight physical ports into one logical port, considering bandwidth of each port is 100 Mbps, the combined bandwidth is 800 Mbps. What if one of the port fails?. Well the rest of the ports take over thus preventing any failure. Let’ see it a little bit practically.

Imagine we have a network as shown below. There are two separate departments named Sales and Engg  in a company which are connected through a router.



There comes a time when the traffic between these two significant departments becomes so intense that the network administrator decides to interconnect the two switches of the respective departments as shown below so that the traffice doesn’t disturb the router. ( CCNA guys, always remember that  switches are interconnected using crossover cables only ).



Considering the importance of the two departments, the network administrator decides not only to provide additional bandwidth but also provide fault tolerance between the departments. Etherchannel satisfies both these requirements.

Now let’s see how to configure etherchannel.  To configure etherchannel, login to SWITCH1. Enter global configuration mode by typing command “config t”. Type the command “interface port-channel 1″ to create etherchannel port trunk. Type command “interface range fastethernet 0/1-8″ to select eight interfaces to assign to our etherchannel port trunk. Type command “channel-group 1 mode on” to assign the interfaces to the etherchannel port trunk.



We can see below that we have successfully configured  etherchannel  on our switch.



Now let’s configure VLAN trunk over the etherchannel logical port trunk. Type command “interface port-channel 1″ to select the etherchannel port. Type command “switchport mode trunk” to  set etherchannel port as trunk port.



Hope this was helpful.

Good evening friends, Today we will see how to configure passwords on Cisco routers and switches. Cisco devices have four types of passwords.

  • Console password : Used to set password for the console access.
  • Auxiliary password : It is used to set password to auxiliary port ( if the switch has one.)
  • VTY lines password : Used to set password for  for telnet and ssh access.
  • Privileged password : Used to set password for privileged access to the switch.

I am not going to show you how to set up auxiliary password here. To see how to set up console password and VTY lines password, go here.

Privileged mode of a Cisco device has some advanced IOS commands that can have disastrous consequences if used by wrong hands. So it is very important to set up a password to access privileged commands. Use the following commands



The “enable” command takes us into privileged mode. The “conf t” mode takes us into global configuration mode which pertains to the configuration settings of the whole switch. The “enable password”  sets a password for the privileged mode. ‘123456’ is the password. The “exit”  command takes us out of the privileged mode. To see if a password has been set for the privileged mode, try entering into privileged mode by typing “en” command. We can see that it prompts us for the password.

Cisco IOS is the internetwork operating system of both the Cisco switches and routers. It has two interfaces command line interface(CLI) and Graphical User Interface(GUI). Since CCNA exam will surely test your knowledge on these interfaces, it is important to get familiar with them.

Cisco’s IOS command-line interface (CLI) is a text-based interface integrated with the IOS. When a switch or router boots up, the IOS loads the startup configuration from NVRAM and displays the IOS prompt, waiting for commands. We can enter the IOS commands at the IOS prompt.

In this article, we will see various command line modes on Cisco routers and switches. For this, we are going to use Packet Tracer. To see what is Packet Tracer and how to install it in both Linux and Windows, go here. For a startup guide on Packet Tracer, see here. Open Packet Tracer  and select a Cisco 2960 switch.



Hover on the switch to see its ports.


Select a Computer from the End Devices and connect them with a Console wire. What we are simulating here is connecting to the switch from a PC through console.



Click on the Host device( Computer ). On the window that opens, click on Desktop tab and Click on Terminal.


The console opens with the switch booting. Switch finishes its booting operation and loads  into user EXEC mode.


Coming to the modes of Cisco IOS, the Cisco IOS has five command line modes.

  • Setup mode
  • User EXEC mode
  • Privileged EXEC mode
  • Global configuration mode
  • Specific Configuraton mode

Setup mode

Setup mode is the initial configuration mode of Cisco switches and routers. They start in setup mode when no startup configuration exists in NVRAM. After completion of the setup mode,  the Cisco IOS transitions to user EXEC mode.

User EXEC mode

The user EXEC mode is the normal operation mode on Cisco switches and routers. The Cisco IOS user EXEC prompt is the switch or router name followed by the ‘greater than’ character >. See all the commands available in user EXEC prompt by typing ‘?’



Privileged EXEC mode

Privileged EXEC mode is the advanced operation mode of Cisco IOS. It has been designed to restrict access to IOS commands that can have adverse effects on the Cisco device and its configuration. To enter privileged EXEC mode type “enable” or “en” .Privileged EXEC prompt is comprised of the switch or router name followed by the # character. To exit the privileged EXEC prompt type “disable”.



To see the commands available in privileged EXEC prompt, type ?.



Global Configuration mode

The global configuration mode is comprised of commands pertaining to the entire Cisco device. In other words, if we need to execute commands to modify the behavior of either the whole switch or the whole router we need to set the IOS in global configuration
mode. Global configuration mode can only be enabled from  privileged
EXEC mode by typing config t” or “conf t”. The prompt in this mode is comprised of the device name followed by “(config)#”.



See the commands available in this mode by typing ‘?’. If we need to execute a command not available in the global configuration mode we should prefix the command by “do”.



Specific configuration mode

The specific configuration mode is used for commands that affect the configuration of either just one part or range of components of the Cisco device. Suppose we want to work on a few interfaces (or ports) on our switch or router we need to enable specific configuration mode. We can enable specific configuration mode only from the global configuration mode by selecting the components we want to work with. The prompt in this mode is comprised of the router or switch host name followed by “(config-<component>)#”.

Let’s select interface fastethernet 0/1 by typing “interface fastethernet 0/1″. 


If we want to run a command not available in specific configuration mode prefix the command by do”. For example, run the command “do show running-config” in specific configuration mode.



We can exit from global configuration mode and specific configuration mode by typing “exit”.

Cisco Certified Network Associate certification has become must for anybody who wishes to start  a career in networking. This certification validates that you have the ability to install,configure and troubleshoot a network. You need  lot of practice for achieving success in this exam. Apart from the labs where you are getting trained for CCNA what if you had a chance to practice at home. Or what if you want to self learn for CCNA? Well for both of the questions above, Cisco Packet Tracer is the perfect answer. To quote from Cisco’s official website,Packet tracer is

“a powerful network simulation program that allows students to experiment with network behavior and ask “what if” questions.”

It further says,

“The simulation-based learning environment helps students develop 21st century skills such as decision making, creative and critical thinking, and problem solving. Packet Tracer complements the Networking Academy curricula, allowing instructors to easily teach and demonstrate complex technical concepts and networking systems design.”

Nothing could have defined that better. This software is available for free from Cisco’s website provided you are a registered Networking Academy student, alumni, instructor, or administrator. Even if you are not one among the above you could still get hold of this software,just google it.

Now I’m gonna show you how to install packet tracer in Windows and Linux.


Any installation in Windows is just clicks and mouse and the same applies to Packet tracer. Click on the exe file downloaded. The below screen appears.Select “I accept the agreement” and click on “Next”.


Setup will show the folder in which the program’s shortcuts will be created. If you want to change the folder, you can change it. Click on “Next”.



Then the program will ask whether to create a Desktop icon and create a Quick Launch icon. Make your own choice and click on “Next”.



Then the summary of the settings we selected is displayed. Click on “Install”.


The installation starts as shown below.



In seconds,installation gets completed and the below screen is shown.Click on “Finish”.



Then the below popup appears asking you to close or restart your computer. Click on “OK”.


As we selected Launch option, Packet tracer is automatically launched.


2. Linux

To install Packet Tracer in Linux, we need a .deb package of Packet tracer which can be downloaded from here. Now I am going to install it in Ubuntu Precise Pangolin (12.04). Download the above file to the desktop.



Start the terminal and see your current working directory by typing “pwd”. If the current directory is not desktop move to the Desktop directory using “cd”. After reaching the Desktop directory, type “ls” to see if the packet tracer binary is there.



Left click on the packet tracer .bin file displayed after typing “ls” above,the entire word will be selected. Then right click and select copy. Now type “chmod +x” and then hit “CTRL+SHIFT+V “to paste the text we copied above. Our command should look like this.

                       chmod +x  PacketTracer533_i386_installer-deb.bin

What chmod +x command does is that it gives all users permission to execute.



Then type “./PacketTracer533_i386_installer-deb.bin” in the terminal.This will start extracting the binary package.



Then terminal prompts us to hit Enter to read the End User License Agreement.Hit Enter.



After displaying a rather long EULA, terminal asks us if we accept the terms of EULA. Type “Y”.



Then system asks us for the sudo password.Type the password and hit Enter.



When the installation is finished, close the terminal,go to Dashboard, if packet tracer is not seen,type ‘pac’ in the search box. When Packet Tracer is shown, click on it.



A messagebox shows up saying that we are starting packet tracer for the first time and our files will be stored in a specific folder. Click on “OK”.



Another message box pops up.Click on OK”.



Packet tracer is started.