Cisco Router Boot Process

A router initially loads the following two files into RAM:

IOS image file: IOS simplifies the basic operation of the device’s hardware components. The IOS image file is stored in flash memory of router.

Initial configuration file: The initial configuration file contains commands that are used to perform the initial configuration of the router and to create the running configuration file stored in RAM. The initial configuration file is stored in NVRAM. All configuration changes are stored in the running configuration file and in the IOS.

The running configuration is changed when the network administrator performs the device configuration. When changes are made to the running-config file, it must be saved to the NVRAM as the initial configuration file if the router restarts or shuts down.

Router Boot Process

The boot process consists of three main steps:

1. Performs POST and loads the boot program.
2. Find and install the Cisco IOS software.
3. Locates the initial configuration file, loads it, or enters setup mode.

1. Power-on Self-Test (POST) is a common process that occurs on almost any computer at startup. POST is used to test the router hardware. When the router is turned on, the software in the ROM chip runs POST. During this self-diagnostics, the router works with the ROM diagnosis of various hardware components including CPU, RAM, and NVRAM. When POST is finished, the router runs the boot program.

After POST, the boot program is copied from ROM to RAM. After entering the RAM, the CPU performs the instructions of the boot program. The main task of the boot program is to find the Cisco IOS and install it in RAM.

Note: If there is a console connection to the router, the results appear on the screen.

2. Typically, IOS is stored in flash memory and copied to RAM for CPU operation. During the self-decompression of the IOS image file, a symbol sequence is displayed.

If the IOS image is not in flash memory, the router can search with the TFTP server. If a full IOS image is not found, a reduced version of the IOS from the ROM is copied to RAM. This version of IOS is used to help diagnose any problem and can be used to install the full version of IOS into RAM.

3. The bootstrap program then looks for the initial configuration file (also known as “startup-config da) in NVRAM. The file contains previously saved parameters and configuration commands. If so, it is copied to RAM as a running configuration file or “running-config”.

The Running-config file contains interface addresses, initiates routing, configures router passwords, and defines other device properties.

If the start-config file is not present in the NVRAM, the router can search for a trivial file transfer protocol (TFTP) server. If the router detects an active connection to another configured router, it sends a broadcast to search for a configuration file over the active connection.

If a TFTP server is not found, the router displays the request to enter setup mode. The setup mode consists of a series of questions that ask the user for basic configuration information. Setup mode is not designed to enter complex router configurations, and network administrators normally do not use it.

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What is ARP in Networking and How it Works?

For IPv4 addresses to resolve to MAC addresses, the frames to be placed in a LAN environment must be the destination MAC address.

When a packet is sent to the data link layer to be enclosed in a frame, the node queries a table in its memory to find the address of the data link layer assigned to the destination IPv4 address. This table is called the ARP table or ARP cache. The ARP table is stored in the RAM hardware of the device.

Each entry or row in the ARP table links an IP address to a MAC address. The relationship between the two values ​​is called a map, which means that you can find an IP address in the table and find the corresponding MAC address. In the ARP table, device assignments are temporarily stored (cached) in the local LAN.

To begin processing, a transmitting node attempts to find the MAC address assigned to an IPv4 destination. If this map is found in the table, the node uses the MAC address as the target MAC in the frame that contains the IPv4 packet. The frame is then encoded in the network environment.

Understanding ARP (Address Resolution Protocol)

The ARP table is maintained dynamically. There are two ways in which a device can collect MAC addresses. The first is to monitor the traffic that occurs in the segment of the local network. Because a node receives frames from the media, it can save the source IP and MAC addresses as mappings in the table. When frames are transmitted on the network, the device completes the ARP table with address pairs.

A device can also receive address pairs by sending an request as shown in the figure. An ARP request is a Layer 2 broadcast transmitted to all devices on an Ethernet LAN. The ARP request includes the IP address and the broadcast MAC address of the target host, FFFF.FFFF.FFFF. Because it is a broadcast, all nodes in the Ethernet LAN receive and examine the content. The IP address responds to the node that matches the IP address in the request. The response is a unicast frame containing the MAC address corresponding to the IP address in the request. This response is used to create a new entry in the ARP table of the sending node.

The entries in the ARP table have a timestamp similar to the MAC table entries in the switches. If a device does not receive a frame from a particular device before the time stamp expires, its entry is removed from the table.

Additionally, static assignment entries can be entered in an table, but this is not very common. Static entries in the ARP table do not expire over time and must be manually removed.

How Does ARP Protocol Work?

What does the node do when a frame needs to create a frame and the ARP cache does not include an IP address assigned to a destination MAC address? When the ARP receives a request to map an IPv4 address to a MAC address, it searches for the map stored in the table. If no input is found, IPv4 packet encapsulation is not performed, and Layer 2 operations notify the ARP that a map is needed.

The ARP then sends an request packet to find the MAC address of the target device of the local network. If a device receiving the request has a destination IP address, it responds with an response. A map is created in the table. Packets of this IPv4 address can now be placed in frames. If no device responds to an request, the packet is discarded because no frames can be created. This encapsulation error is reported to the upper layers of the device.

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What is CCIE (Cisco Certified Internetwork Expert)?

CISCO is the world’s leading company in Information Technology, and CCIE (Cisco Certified Internetwork Expert) is one of the most respected certifications issued by the Information Industry worldwide.

CCIE is an advanced certificate that recognizes training, experience, and skills in structuring, testing, and troubleshooting complex networks.

Cisco CCIE and New Cisco Certificates

By continuing to analyze the announcement of Advanced Certificates issued by Cisco on Monday (June 10th), I now want to address the issue of professional-level certificates.

Professional-level certifications have never been the largest CCNA level, but for many years have been a clear path of professional development for those wishing to pursue a career in networks.
The natural continuity of CCNA (and therefore undertaken by most people) emerged as the step before CCI, and over the years they have become 8 different certifications in different areas of networks.

This reorganization of the certification system has led to significant developments that we need to consider.

General aspects of the next level of this CCNP Professional level certificates do not have formal prerequisites. That is, there is no longer a prerequisite for having a valid CCNA certificate.

To get a certificate, you still need to pass multiple exams, but now you only need to pass 2 exams.

In each architecture, however, there are several specialist options, ranging from 3 to 6 Concentrations that will certainly lead to different specialties.

Each Concentration exam results in Expert certification on a particular technology.

The diversity of “CCNPs” has been significantly reduced. There is now a professional certificate for each architecture: Enterprise, Data Center, Security, Service Provider, and Collaboration.

Exams will be valid until February 23, 2020.

New certification exams will be available from 24 February 2020.

Existing certificates remain in effect until each reapprovals date.

Those who have received a valid CCNP certificate by February 24 will have the corresponding CCNP certificates.

As of February 24, those who hold a CCNP Routing and Switching Certificate, CCNP Wireless and/or CCDP, will receive the new CCNP Enterprise certificate that intensifies these three.

For those who are in the certification process but do not meet all requirements from 23 February, an immigration plan is planned, which partially recognizes the approved exams to qualify for new certificates.

In any case, relevant formal training is planned for next July.

There is currently no official explanation of how Cisco NetAcad academies will pass.

There is an online tool to facilitate the transition to the new system: Migration Tool

Professional Level Certificates

  • There are no formal prerequisites.
  • In each case, the re-certification period is 3 years.
  • In each case, the certificate is obtained by passing the Core exam of the desired architecture and a Concentration exam in particular field technology, 2 exams are required.
  • For each exam, Cisco will provide formal training through the Learning Partners.

Certificates are issued in 5 architectures recommended by Cisco:

  • CCNP Enterprise
  • CCNP Data Center
  • CCNP Security
  • CCNP Service Provider
  • CCNP Collaboration

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How to Install Cisco Packet Tracer 7.2.2 in openSUSE Linux OS

OpenSUSE Leap 15.1 was released last May 2019. Ready to use and enjoy your computer, this is a stable version of the GNU / Linux distribution.

Today, openSUSE developers are pleased to announce that they are updating the new version of their operating system to the new openSUSE 15 version, which includes updated components and technologies based on the next SUSE Enterprise Linux 15 series and designed for advanced users.

With the latest release of SUSE Linux Enterprise 15, support is provided for local cloud applications that enable companies to move to the next level.

At this year’s Open Source Summit in Shanghai, China, SUSE made a big statement about the release of SUSE Linux Enterprise 15 Service Pack 1. He said his products would support both traditional and workloads. As a result, companies using this operating system can benefit both today and in the long run.

After you give some information about openSUSE, let’s move on to installing Packet Tracer, great software for preparing for Cisco exams on this system.

How to Use Packet Tracer on SUSE Linux

The latest version of Packet Tracer, developed by Networking Academy, customized and released for free, is 7.2.2.

To install Packet Tracer on your Linux computer, follow these instructions:

Step 1: First, download the Packet Tracer for Linux systems by clicking here.

Step 2: Start the installation by double-clicking on the downloaded setup file.

Step 3: In the first step of the Packet Tracer installation wizard, click Next.

Step 4: Configure the installation folder to / opt / pt / and click Next.

Step 5: After configuring the installation location, accept the simulator’s license agreement and click Next.

Step 6: In the Ready to Install phase, click the Install button to start the installation.

Step 7: Enter your root password during installation and click OK to continue the installation.

Step 8: After installation, click Finish and execute the packettracer command on the terminal to run the program.

Step 9: If the Cisco simulator software is not running on your openSUSE operating system, download the libpng package using the command below.


Step 10: Since deb packages are not installed on SUSE OS, download and install the DPKG package with the command below.

sudo zypper install dpkg

Step 11: Now you can run your Packet Tracer software by copying to /opt/pt/bin/ after executing the following commands!

mkdir cpt; dpkg -x libpng12-0_1.2.50-2+deb8u3_amd64.deb ./cpt
sudo cp ./cpt/lib/x86_64-linux-gnu/ /opt/pt/bin/

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How to Install Cisco Packet Tracer 7.2.2 in Ubuntu 19.10 (Eoan Ermine) OS

Ubuntu is a community-developed system for laptops, desktops, and servers. Whether at home, at school, or at work, Ubuntu includes everything you might need, from word processors and email applications to web server software and programming tools.

Ubuntu will always be free. You do not pay for a usage license. You can download, use, and share Ubuntu with your friends, family, school, or business for free.

Every six months, a new version of the desktop and server version is released. This means you will always have the latest applications that the open-source world can offer you.

Ubuntu was designed with security in mind. In desktop and server versions, you will receive security updates freely for at least 18 months. With the Long Term Support (LTS) version, you have three years of support on the desktop version and five years on the server version. There is no extra payment for the LTS version, we do our best for everyone on the same free terms. Updates to the new version of Ubuntu are free and will always be free.

PT (Packet Tracer) is an interactive network simulation and learning tool. This tool allows you to create network typologies, simulate a network with multiple visual presentations, basically a didactic support tool.

It provides students with networking and troubleshooting experiences with virtually unlimited number of devices without having to buy real routers or switches.

After talking a bit about Ubuntu and Packet Tracer, let’s get to the point.

How to Use Packet Tracer on an Ubuntu PC

The latest version of Ubuntu is 19.10 (Eoan Ermine). The PT version is also 7.2.2

Before installing on your Linux computer, download the PT to your computer and then follow the steps below for step-by-step installation.

Step 1: Right-click on your Ubuntu desktop and open the terminal.

Step 2: Use the following command to change the permissions for the .run file you downloaded to your computer:

chmod +x

Step 3: Use the following command to start the GUI wizard of Packet Tracer:


Step 4: Accept the license agreement of the Cisco simulator and click Next to complete the installation. Then, the PT will try to open, but it won’t work because you need to install several dependent packages.

Step 5: To run Packet Tracer, you must first install the Libpng package. Use the following commands to install libpng:

sudo dpkg -i libpng12-0_1.2.50-2+deb8u3_amd64.deb

Step 6: When installing Libpng, you will also need to install this package if you receive a multiarch not installed error. Therefore, to install multiarch, use the following commands:

sudo dpkg -i multiarch-support_2.29-0ubuntu2_amd64.deb

Step 7: After installing the Multiarch package, try to install libpng again.

Step 8: After installing libpng, open the program by running the packettracer command on the terminal.

Step 9: Damn! Packet Tracer does not work again!

Step 10: The reason why Packet Tracer doesn’t work is You need to extract the libpng.deb file to the folder and copy the file to /opt/pt/bin/. To do this, use the following commands:

mkdir cpt; dpkg -x libpng12-0_1.2.50-2+deb8u3_amd64.deb ./cpt
cp ./cpt/lib/x86_64-linux-gnu/ /opt/pt/bin/

Step 11: After fixing Ubuntu error, you can now use Packet Tracer on your computer without a problem!

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How to Install Cisco Packet Tracer 7.2.2 in Debian 10 Buster OS

Debian is an organization created by volunteers dedicated to developing free software and developing the ideals of the free software community. The Debian Project began in 1993 when Ian Murdock invited all software developers to contribute to a completely consistent distribution based on the relatively new Linux kernel at the time.

Initially supported by the Free Software Foundation and influenced by the GNU philosophy, the relatively small group of passions grew over the years to become an organization of around 1062 Debian developers.

Packet Tracer is an interactive network simulation and learning tool for instructors and students. This tool allows users to create network topologies, configure devices, deploy packages, and simulate a network with multiple visual presentations. Packet Tracer focuses on better supporting network protocols taught in the CCNA curriculum.

Today we going to show you how to run the Packet Tracer on Debian 10 Buster.

Debian 10 Buster was released as a stable version after 25 months and will be supported by Security and Long Term Support for 5 years.

If you want to prepare for Cisco exams with your Linux system, you can use Packet Tracer.

Step 1: Download Packet Tracer for Linux to your desktop and then turn on your terminal.

Step 2: Set the file permissions on your terminal with chmod +x

chmod +x

Step 3: Run ./ to start the installation.


Step 4: Install the Cisco Packet Tracer step by step on your system and use the packettracer command on the terminal to run it.

Step 5: If you installed the program but it does not work, download the libpng package with the command below.


Step 6: To install libpng12 in Debian, use the command dpkg -i libpng12-0_1.2.50-2 + ​​deb8u3_amd64.deb.

dpkg -i libpng12-0_1.2.50-2 + ​​deb8u3_amd64.deb

Step 7: You may need to install the multiarch-support package when installing Linpng. If you see a warning like this, run the following command to install multiarch:

sudo apt-get install multiarch-support

Step 8: After installing Multiarch, install libpng12. If you get an error like the one below, copy to /opt/pt/bin/ folder.

unable to install new version of '/usr/lib/x86_64-linux-gnu/': No such file or directory

Step 9: To copy using the terminal, use the following commands:

mkdir cpt; dpkg -x libpng12-0_1.2.50-2+deb8u3_amd64.deb ./cpt
cp ./cpt/lib/x86_64-linux-gnu/ /opt/pt/bin/

Step 10: After fixing error, you can now run and use your Packet Tracer on your Debian PC!

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How to Install Cisco Packet Tracer 7.2.2 on Linux Mint 19.2 OS

The latest version of Cisco’s popular network simulator is now available for download.

Unlike the previous version, Cisco Packet Tracer 7.2 comes with major improvements, including a reconfigured user interface theme.

To download the new version of Packet Tracer, we’ll need to create a user account at Cisco Networking Academy (free). This will allow us to access to download software as well as automatically register for an online course on cybersecurity.

As you know, Linux Mint is derived from Ubuntu, which has become very popular in recent years and leaves behind its basic distribution.

After the release of the new version of Linux Mint 19.2, we will share a simple installation guide of Packet Tracer, so that it can be useful for those who prefer to try this operating system on their computers or a virtual machine.

Linux Mint 19.2 will be supported by 2023 and comes with up-to-date software and offers improvements and new features to make your desktop experience more comfortable.

How to Setup and Run Packet Tracer on Linux Mint

Step 1: After installing the Mint OS, you can install Packet Tracer and create complex network projects to prepare for Cisco Routing or Switching exams.

Step 2: Download the Cisco simulator program from Netacad to your computer.

Step 3: Cisco previously published the setup file as tar.gz for Linux. The file extension is now published as .run. Copy the file you downloaded to the desktop, and then open Terminal.

Step 4: Use the “chmod +x” command to change the permissions of the Run file.

chmod +x

Step 5: Now use the command “./” to start the installation.

Step 6: Complete the installation with the GUI setup interface.

Step 7: Run the packettracer command to run the software after installation. If the software doesn’t work or doesn’t respond, you need to install the libpng package.

Step 8: Run the following commands to download and install libpng for Mint.

dpkg -i libpng12-0_1.2.50-2+​​deb8u3_amd64.deb

Step 9: When you run the “packettracer” command on the terminal again, you will be able to run the simulator software.

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How to Install Cisco Packet Tracer 7.2.2 in Kali Linux 2019.4 OS

Cisco Packet Tracer is a software developed by Cisco Networking Academy department. This software allows you to design multiple scenarios in the field of networks because it allows you to develop different types of networks with wired and wireless media; Allows you to use dynamic routing protocols.

It also allows for the development of convergent networks by implementing equipment with multiple services that act as servers, all transmitted and retransmitted packets can be visualized by a traffic analyzer that includes the program, allowing you to see how negotiation is set up Different transmission and routing protocols make their understanding easier.

Packet Tracker is available for different systems such as Windows (32 and 64 bit), Linux (64 bit only), Android and iOS. You must be logged in to access your content.

Installing on both Android, iOS, and Windows requires no additional steps than downloading your installer from executable Windows from the relevant application market (Google Play Store, App Store) or Web page.

This article is intended to assist employees and trainees to install and run Packet Tracer software under a Kali Linux Kali system (based on Debian).

Step 1: First, visit the Netacad website, create a new account and download Packet Tracer for Linux.

Step 2: After downloading the installation file, copy the file to the Kali desktop and open Terminal in that location.

Step 3: Test your Internet connection, and then use the command below to change the permission of the Packet file.

chmod +x

Step 4: Use the command below on the terminal to start the Packet Tracer installation.


Step 5: Finish the installation using the GUI setup wizard. And then run “packettracer” in the terminal and open the application.

Step 6: You will see the Starting Cisco Packet Tracer message, but the program will not run! Because on Kali you need to install some additional packages for this software. Add the following address to the Sources list and run the apt update command.

nano /etc/apt/sources.list
deb stable main contrib non-free
apt update

Step 7: If the libpng installation fails, you will also need to install the multiarch package. Use the following command to install the Multiarch package.

apt install multiarch-support

Step 8: When you try to reinstall libpng, you will see that the process was successful this time!

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What is CCENT (Cisco Certified Entry Network Technician)?

What is Cisco CCENT?

The Cisco Certified Entry Network Technician (CCENT) Certificate supports the ability to set up, run, and resolve a small enterprise network, including a basic security network. Professionals with this certificate have the skills necessary for basic network support positions.

This certificate includes:

  1. Basic elements of the network
  2. WAN technologies
  3. Basic security
  4. Wireless concepts
  5. Routing Basics
  6. Simple Network Configuration

The CCENT Certificate is the first step at Cisco to obtain the CCNA Certificate covering the networks of more complex companies.

It is intended for students at Cisco Networking Academy in the ICT industry looking for entry-level jobs or waiting to meet their base requirements to acquire more specialized ICT skills.

The preparation of this certification consists of two courses:

Introduction to networks

  • Network scanning
  • Setting up a network operating system
  • Network protocols and communication
  • Network access
  • Ethernet
  • Network layer
  • Transport layer
  • IP Address Assignment
  • IP network section on subnets
  • Application layer
  • This is a network

Basic Routing Policies

  • Introduction to switched networks
  • Configuration and basic switching concepts
  • VLAN
  • Routing Concepts
  • VLAN communication
  • Static routing
  • Dynamic routing
  • OSPF single area
  • Access Control Lists
  • DHCP
  • Network address translation for IPv4

The exam corresponding to this certificate is 100-001 Interconnection Cisco Networking Devices Part 1 (ICND1). Evaluate the ability to set up, run and solve events in a small network.

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What is CCNA (Cisco Certified Networking Associate)?

For basic network engineers, CCNA stands for Cisco Certified Network Associate, a certification program that helps you increase your investment in basic network knowledge and increases the value of your employer network.

CCNA Certification verifies the establishment, configuration, operation, and troubleshooting of medium-sized routers and switching networks, including the implementation and verification of connections to remote sites in a WAN.

To obtain a CCNA header and certification change, you will need to obtain an approval score on the Cisco # 200-120 exam or by combining both Cisco Network Device Interconnection approval.

Pass the ICND1, which validates the knowledge and skills required to set up and issue a CCENT certificate, which means the Cisco Certified Entry Network Technician. Confirmation scores are determined by statistical analysis and may vary.

At the end of the exam, the candidates receive a final report as well as the loss of responsibilities for the exam section and the passing score of the exam. CCNA does not publish an exam on approval points due to exam questions, and approval points are subject to change without notice.

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