Articles Tagged ‘internet’

Binary & The Internet Protocol

To understand the Internet Protocol, we need to learn and understand Binary. It is very important to know and understand Binary because part of the IP protocol is also the "Subnetting" section which can only be explained and understood when an IP Address is converted to Binary!

This article deals with the analysis of IP addresses and covers the conversion of IP address to binary. We explain the conversion process with much detail using our well known diagrams. At the end of the article, readers will be able to understand and explain how IP address to binary conversion is performed and also calculate quickly the 32bit addressing scheme.

Those who are experienced in Binary can skim this section quickly, but do have a look through.

A lot of people are not aware that computers do not understand words, pictures and sounds, when we interact with them by playing a game, reading or drawing something on the screen. The truth is that all computers can understand is zeros (0) and ones (1) !

What we see on the screen is just an interpretation of what the computer understands, so the information displayed is useful and meaningful to us. 

Binary: Bits and Bytes

Everyone who uses the Internet would have, at one stage or another, come across the "Byte" or "Bit" term, usually when you're downloading, you get the speed indication in bytes or KBytes per second. We are going to see exactly what a Bit, Byte and KByte is, so you understand the terms.

To put it as simply as possible, a Bit is the smallest unit/value of Binary notation. The same way we say 1 cent is the smallest amount of money you can have , a Bit is the same thing but not in cents or dollars, but in Binary.

A Bit can have only one value, either a one (1) or a zero (0). So If I gave you a value of zero: 0, then you would say that is one Bit. If I gave you two of them: 00, you would say that's two Bits.

Now, if you had 8 zeros or ones together: 0110 1010 (I put a space in between to make it easier for the eyes) you would say that's 8 Bits or, one Byte ! Yes that is correct, 8 Bits are equal to one Byte.

The picture below gives you some examples:

ip-binary-1

It's like saying, if you have 100 cents, that is equal to one Dollar. In the same way, 8 Bits (doesn't matter if they are all 1s or 0s or a mixture of the two) would equal one Byte.

And to sum this all up, 1024 Bytes equal 1 KByte (Kilobyte). Why 1024 and not 1000 ? Well it's because of the way Binary works. If you did the maths, you would find the above correct.

ICMP Protocol

This section contains articles covering the ICMP Protocol. This popular protocol is used by network devices such as routers, servers, workstations to send error messages indicating that a requested service or host/router is not available or unreachable. 

Articles provided cover the introduction to the ICMP protocol, Echo (Ping) and Echo-Reply (Ping reply)messages, the popular Destination-Unreachable message, Source Quench message, Redirect message and Time Exceeded message.

Detailed diagrams and protocol structure graphs compliment our articles, making them easy to understand and follow.

Introduction to Cisco VIRL – Virtual Internet Routing Lab & Other Simulation Tools

Cisco VIRL – Virtual Internet Routing LabOne of the most difficult things for people who are starting out in a networking career is getting their hands on the equipment. Whether you are studying for Cisco certification or just wanting to test certain network behaviors in a lab, no one would argue that practicing is the best way to learn.

I have seen people spend hundreds or thousands of dollars (myself included) buying used networking equipment in order to build a home Cisco lab to gain practical experiences and study for certification exams. Until a few years ago it was the only option available, or you had to rent lab hours through one of the training companies.

Other Simulation Tools

GNS3 is a well-known free network simulation platform that has been around for many years. Cisco IOS on UNIX (IOU) is another option for running Cisco routers in a virtual environment. It is a fully working version of IOS that runs as a user mode UNIX (Solaris) process. IOU was built as a native Solaris image and runs just like any other program. One key advantage that Cisco IOU has is that it does not require nearly as much resources as GNS3 and VIRL would require. However, the legality of the source of Cisco images for GNS3 is questionable.

Cisco VIRL Network Topology

Figure 1. Cisco VIRL Network Topology

If you are not an authorized Cisco employee or trusted partner, usage of Cisco IOU is potentially a legal gray area. Because of lack of publicity and availability to average certification students and network engineers, online resources are limited and setting up a network takes much more effort. Also, due to missing features and delays in supporting the recent Cisco image releases, Cisco is not recommending them to engineers and students.

Read our review on "The VIRL Book" – A Guide to Cisco’s Virtual Internet Routing Lab (Cisco Lab)

Here Comes Cisco VIRL

Cisco Virtual Internet Routing Lab (VIRL) is a software tool Cisco developed to build and run network simulations without the need for physical hardware.

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