How does packet routing work

I have been teaching computers and electronics for nearly 40 years now, and I personally find that you take a very nice middle-of-the-road difficulty level on your explanations without hiding behind jargon. The hardest thing in teaching technology is to decide what level to pitch your presentation to, and you do it brilliantly. Two paragraphs? LOL So stick with what you do.

Nobody else is doing it as well as you. In fact, your dedication to helping others is fantastic. I for one hope that you are able to keep it up for many years to come! Best Regards.. Great work. Really appreciate your time and hard work in putting up difficult as well as obvious articles which do require a detailed explanation. Hats off! Keep up the good work. Great article! Always informative for any level. Visual aides really drive home to make a solid point.

This documents are a great source of information. I used them all the time in my classes. I would love to have follow up questions related to the article that can be assigned to the students.

Thank you. Meh, the site converted the name I used for the alias to a URL. Any way, let me try it a different way: you can alias www to point to the name of domain without the www, and the same with other names meaning www is not the only one you can alias.

I have few doubts. Do help me out. As source IP address and Destination IP address do not change so with the help of destination IP address,destination host will get identified. Save my name, email, and website in this browser for the next time I comment. Notify me of followup comments via e-mail. All rights reserved Terms of Service. DNS Most of us would have used google.

Faisal Hasan August 8, , am. Jalal Hajigholamali August 8, , pm. Hi, thanks, helpful article…. Biff Martin August 8, , pm. Anonymous August 8, , pm. Very well put together Course 15 Aug, I liked all of the courses and also the teachers. Fantastic Course! A a returning teacher who has always taught FE and HE and able to steer away from networking I have found it A different perspective 13 Jul, Previously, we looked at a simplified IP packet, with fields for the source and destination addresses as well as the data it transports.

In a real IP packet header there are several other fields. IP is a routed protocol : routers examine IP packets and route them out of an interface based on the destination IP address. X address. So the router is connected to two different IP networks, which are automatically placed into the routing table. The default network, 0. Each router examines and sends each IP packet individually — this is called packet switching. If the network changes, due to congestion or faults, routers can use an alternative interfaces to reach a destination.

So packets may travel over different routes to reach the same destination. Switches switch data frames between ports, whereas routers route IP packets between interfaces. Want to keep learning? This content is taken from Raspberry Pi Foundation online course,. It does not go into great depth, but covers enough of each area to give a basic understanding of the concepts involved.

For any unanswered questions, a list of resources is provided at the end of the paper. Any comments, suggestions, questions, etc. Where to Begin? Internet Addresses Because the Internet is a global network of computers each computer connected to the Internet must have a unique address. Internet addresses are in the form nnn. This address is known as an IP address. IP stands for Internet Protocol; more on this later.

The picture below illustrates two computers connected to the Internet; your computer with IP address 1. The Internet is represented as an abstract object in-between. As this paper progresses, the Internet portion of Diagram 1 will be explained and redrawn several times as the details of the Internet are exposed.

In any case, if you are connected to the Internet, your computer has a unique IP address. It's called ping , probably after the sound made by older submarine sonar systems. If you're using a flavor of Unix, get to a command prompt. Type ping www. The pinged computer will respond with a reply. The ping program will count the time expired until the reply comes back if it does. Also, if you enter a domain name i. More on domain names and address resolution later.

Protocol Stacks and Packets So your computer is connected to the Internet and has a unique address. How does it 'talk' to other computers connected to the Internet? An example should serve here: Let's say your IP address is 1. The message you want to send is "Hello computer 5. Obviously, the message must be transmitted over whatever kind of wire connects your computer to the Internet. Let's say you've dialed into your ISP from home and the message must be transmitted over the phone line.

Therefore the message must be translated from alphabetic text into electronic signals, transmitted over the Internet, then translated back into alphabetic text. How is this accomplished? Through the use of a protocol stack. Every computer needs one to communicate on the Internet and it is usually built into the computer's operating system i. Windows, Unix, etc. Hardware Layer Converts binary packet data to network signals and back.

If we were to follow the path that the message "Hello computer 5. If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data. This is because data sent over the Internet and most computer networks are sent in manageable chunks. On the Internet, these chunks of data are known as packets. Each packet is assigned a port number. We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port.

This is where each packet receives it's destination address, 5. Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line. On the other end of the phone line your ISP has a direct connection to the Internet.

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Nadeem Unuth. Freelance Contributor. Nadeem Unuth is a former freelance contributor to Lifewire who specializes in information and communication technology with a focus on VoIP. Updated on June 24, Tweet Share Email.