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Computer networks consist of many different components, technologies, and protocols that work together.
In this tutorial / course, we look at the basics of how computers connect to a TCP / IP network.
This tutorial is for those who need to learn the basics of how networks work, and how the components fit together so they can set up a small home / office network.
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Getting Started
- To be Connected (cable or Wireless) this is known as the connection media.
- To have a common language. in Networking this is known as a protocol.
- To have An Address.
Connecting Computers Together
Early computer networks were used as a way to connect computers together in a wired network.
Most modern wireless networks (wi-Fi) are used because the main communication media and networks tend to be a combination of wired and wireless networks.
The diagram below shows a wired Ethernet network. To work, you must connect each device to a hub or Ethernet adapter.
However, they are all connected together and shared by the same media that we see later.
For the wireless network, devices must connect to a wired access point as shown in the graph below.
However, logically again they share and compete to reach the same media.
Wireless access is usually equipped with a built-in Ethernet hub that allows them to connect to a wired Ethernet network.
Ethernet Addressing
In order to communicate with each other, each computer needs a unique address.
This is called the MAC address (the media access control address) and is integrated into the network card.
The address is often called the physical address and the Ethernet address.
48-bit (new 64-bit format) and fixed by the manufacturer, meaning it can not be changed.
It is displayed as 6 hexadecimal digits separated by a colon, for example
00: 01: 6C: 67: 02: C6
In Windows, open the cmd-Run Start menu, and then enter cmd and return.
Enter ipconfig / all in the window and press Return.
Links and Networks
Ethernet is a data-link protocol. Also known as Level 2 protocol on OSI and TCP / IP network models.
Computers can communicate with each other using Ethernet only, and without a network protocol, but they are not practical.
An Ethernet (street) link contains computers (homes) that in turn contain numbers (Ethernet, Mac Address, or physical address).
However you can get many streets and streets connected. (Crossroads, crooked, etc.) to form a network of streets.
Routers divide Ethernet connections into networks.
Links and Networks
All modern networks (home, office, corporate, and Internet) use TCP / IP network protocols.
The network protocol also includes addresses (IP address), which are not fixed but are assigned by a network administrator or by a service called DHCP (Dynamic Host Configuration Protocol).
Ethernet Broadcasts, Broadcast Domains and Collisions
To send a message to all computers on an Ethernet network, the MAC Address of all is used. And therefore
FF: FF: FF: FF: FF: FF
A broadcast domain is the effective broadcast band, which can be restricted by entering the level 3 network devices (IP level), for example routers.
The broadcast will be re-broadcast via axes, switches, bridges (level 2) and repeaters (level 1).
Level 1 = Physical like any media devices cable = repeater
Level 2 = Data Link = Ethernet devices are hubs, switches, and bridges
Level 3 = Network = IP Protocol – Devices are routers
A collision area is a section of a network where beams can collide, and interfere with each other.
Network devices (bridges and switches) operating at level 2 (data link layer) can create separate collision domains.
Although bridges and switches divide the network into separate collision domains, computers are still part of the same broadcast domain.
Devices on the left of the bridge / switch can communicate with each other, and do not affect the devices on the right side of the switch and vice versa.
Bridges vs Switches
Bridges and switches have very similar functions, and today you can only buy transformers.
Bridges were used to join network segments, ie LAN to LAN, while switching connected devices.
Hubs vs Switches
The centers operate at the actual level and were once the primary mechanism for connecting computers together.
Hubs does not create a separate collision domain; it only replicates packets.
They have been replaced by switches.
Data Frames and Packets
Data is transferred between computers in data frames or packets.
The term framework uses data units at the data link level and the term pack for data units and the network level.
Thus we have Ethernet frames and IP packets.
The data window contains the data management and window information.The concept used to describe data frames is the concept of letter and envelope.
The message is the data that is placed inside an envelope that contains addressing information.
The concept of data being inserted into an envelope is frequently used in data communications, an important concept for understanding it.
Simply insert the envelope containing the data (character) into another envelope and so on.
Although the Ethernet protocol alone is sufficient to obtain data between two nodes on an Ethernet network, it is not used on its own.
Ethernet is what is known as a data link protocol, and for networks we need a network protocol that is, in our case, IP.
Again, the IP protocol is not used in isolation, but as part of a set of protocols called TCP / IP.
However, the IP protocol contains important IP addresses, which are used to connect computers together over the Internet, and in local networks.
The graph below shows how to place data within the protocol envelopes (headers).
At the receiving end are discharged in reverse order.
IP Addresses
Each home network device has an IP address, but what is an IP address? And why is it required?
An IP address is the address that matters most to us, as it is a logical address, which means that it has been customized by us and can be changed.
Existing networks use IPv4 addresses. IPv6 addresses are provided but are unlikely to affect the home / small office networks for several years.
An IP address (IPv4) is a 32-bit address that is written in dotted decimal and looks like this:
192.168.0.1
The title contains four components, each component separated by a period (.). So from this model:
a B C D
For home / small office networks, it is not really important to understand the different address categories (A, B, C, D, etc.) or technical aspects of subnets where IP addresses are automatically assigned.
When troubleshooting network problems, you’ll need to be able to specify network addresses, whether the device is one, and whether that address is valid.
Since home / small office networks use a device called a NAT router, IP addresses used on almost all home networks are a non-routable IP address that starts at 192.
This IP address is automatically assigned by the DHCP server that is part of the NAT router.
Problems arise when customers can not obtain an IP address from the DHCP server because of network / router problems.
If the client can not obtain an IP address, some clients automatically assign an IP address. Of the reserved range 169.254.0.0-169.254.255.255 or simply have an IP address of 0.0.0.0.
In either case, it is unlikely to work correctly because clients with a 192. address are located on a different network for customers who have a 168. address, although they may be next to each other on the same actual cable.
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