Networking

Computer Networking Definition

In the broadest terms, people often view the Internet as a cloud. You put your data in one place, and it comes out the place you want it to on the other side, with what happens in between obscured in the fog.

In reality the internet is tens of thousands kilometers of fiber optic cable, hundreds of thousands to millions of kilometers of copper wire, and hardware and software connecting them all together in a redundant, fast, and self-sufficient network. But not to worry, it’s not that bad: you only have to worry about a very small portion of the network, you can let someone else worry about the rest.

A Metaphor For The Internet

Important

The information from this section is reused throughout the rest of the course.

Because the internet feels like smoke and mirrors to a lot of people, a concrete physical metaphor could be very helpful in explaining both the parts of the internet and how it all comes together.

The best metaphor to use is how good old fashion snail mail is transferred around and the network of roads crossing the country.

Let’s start with a building. Buildings can be described in two different ways. They have a physical description, “The Arlington Career Center is a two story cement building of the Brutalist architectural style with a circular driveway in front of its main entrance.” This is a description that is fixed and (fairly) hard to change. On the internet, this would be your computers MAC address. Buildings can also be described by the street address assigned to them by their City or County and the US Postal Service, as in 816 South Walter Reed Drive, Arlington, VA 22204.

Your Local US Postal Service is a set of buildings that route letters and packages between different post offices. Letters and packages go into one Post Office and get routed from that office to a distribution center. The distribution center then sends them to another major distribution center and so on until it reaches the distribution center that serves the remote Post Office nearest its destination. They are then sent to the remote Post Office serving the zip code of the destination address from where they are delivered to their destination.

The address of the building is very much like an IP address you’d have assigned to you by who you pay to get on the internet. The streets and surrounding neighborhood you’re in could be considered a local area network, where each house has it’s own address, and they’re all connected. The State and City or County is your ISP, most ISPs have a local branch that’s for your region, which could be related to your city/county, the full ISP is the State, and the Internet is a country.

A Working Metaphor for the Internet

• House - (address vs. physical description)
• Local Streets / Neighborhood - LAN
• State, City/County - ISP, local division of ISP
• Country - Internet
• Major Roads (US routes / Bigger State Routes) - Internet Connectivity
• Highways - Internet Backbones
• Post Office - Router (GET Picture of 495/395/95)
• Intersection - Hub
• Highway Intersection (Mixing Bowl) - Switch

The TCP/IP Model

The TCP/IP Model is a specification for computer network protocols. TCP/IP defines a set of rules to enable computers to communicate over a network. It specifies how data should be formatted, addressed, shipped, routed and delivered to the right destination.

TCP/IP describes the top 4 layers of a 5 layer Internet protocol stack.

The first layer is called the Physical layer. This layer is responsible for encoding and transmitting data over network communications media. It operates with data in the form of bits which are sent from the Physical layer of the sending source and received at the Physical layer of a destination source. When you hook up a computer using an Ethernet cable you are connecting that computer on the Physical layer. This Physical layer is the lowest level of the TCP/IP Model.

The next layer is the Data link layer. This layer is used to move packets from the network layer on two different hosts. The process of transmitting packets on a link layer can be controlled in the software device driver for the network card and on firmware. Different protocols are used for different types of networks. Broadband Internet access uses PPPoE as the protocol. For a local wired network, Ethernet is used. For local wireless network, IEEE 802.11 is used.

The next layer is the Network or Internet layer. This layers gets data from a source network to the destination network. This generally involves routing the packets across a network of networks (also known as internet work). This is where IP (Internet Protocol) comes in. IP performs the basic task of getting packets of data from source to destination.

The next layer is the Transport layer. The transport layer’s responsibility is end-to-end message transfer. There are 2 categories of end-to-end message transmission: connection-oriented (TCP) or connection less (UDP). The transport layer provides this service of connecting applications together through the use of ports. This layer offers reliability and error control.

The fifth and final layer is the Application layer. This layer refers to higher-level protocols used by most applications for network communication. An example of application layer protocol is FTP (File Transfer Protocol). Data coded according to application layer protocols are then encapsulated into one or more transport layer protocols which in turn use lower layer protocols to effect actual data transfer.

How to Turn Your Windows 10 Laptop into a Wi-Fi Hotspot 

1. netsh wlan show drivers - This will let you know if your laptop supports virtual hotspot feature.

2. netsh wlan set hostednetwork mode=allow ssid= key=   

    SSID means network broadcast name. Key means the passphrase. ie your desired password.

3. netsh wlan start hostednetwork
    Will show your newly created hosted network.

4. netsh wlan show hostednetwork    Will show created hosted network details.

    Now you have to share your Wired or Wireless connection. Just open Run box and enter ncpa.cpl 
    You can watch video to see how it is done.

5. netsh wlan stop hostednetwork
    This will stop the shared hosted network you created.