In this tutorial we will be discussing network error collision concepts and how to be avoided. When sharing peripherals on a network such as Network Printers, Files and Folders etc, errors may occur. Therefore we need a method to govern the whole network infrastructure. This is called "Network Access Method" and it will determine which PC can have access to the shared medium.
Each machine connected to a network is called a "node". The access method embedded in the NIC (network interface card) takes control of the transfer of data across the network.
There are various methods to take care of data transmission errors in the mechanism itself such as CRC32 (Cyclic Redundancy Check). Basically, it checks and compares the data traveled to the other end, if it's valid and completed. If this fails, it will resend another transmission.
So, the methods that we will be discussing are CSMA/CD, CSMA/CA, Token Ring Passing, FDDI.
What is CSMA/CD?
CSMA/CD stands for "Carrier Sense Multiple Access / Collision Detection" and its purpose is to check whether the network has an available slot to start the passing data. It waits and listens until there is space for the data to be traveled along the
medium. This technique doesn't stop collisions from happening, but it helps. Makes use of 802.3.
What is CSMA/CA?
CSMA/CA stands for "Carrier Sense Multiple Access / Collision Avoidance" and its purpose is to avoid collision by sending Warning messages before sending the data itself. Data may not occur, but warning messages do. So it's still not a reliable method to relay on. Makes use of 802.3.
What is Token Ring Passing?
This is basically the new method designed by IBM, introduced in the 1990's and yes you've guess it. It works by sending a token around a completed electronic virtual ring. Let me demonstrate on how it works. Let's say there are four available computers on a network topology which are PC1, PC2, PC3 and PC4. Now, PC2 wants to transmit a message packet to PC4. The packet leaving PC2 will need to pass to PC3 and then forwarded to PC4 in a circular movement. This will make the token set to flag "busy". As PC4 has completed receiving the data needed it will eventually send the packet header (message frame) back to PC2. Then the packet is set to "idle" state and will wait for another PC that need to transmit data across the network. A break in the network cable will result in network failure. Makes use of 802.5.
What is FDDI?
FDDI stands for "Fibre Distributed Data Interface" and it consists on two rings made from Optical Fibre. These rings are placed in an opposite direction of each other. The first ring is called the primary ring whilst the other is called the secondary ring. As you start transmitting data and the circuit gets broken, it automatically jumps on the second ring.
An advantage over the Token Ring Topology is that with FDDI you can set priorities. For example you can set priority on a networked printer or the server that will make it respond to requests from clients very quickly.
The standardisation for referring to the Ethernet protocol is called "IEEE 802.3". IEEE stands for "(Institute of Electrical and Electronics Engineers, Inc)"
Ethernet is the standard communications protocol built in network hardware and software used for LAN's (Local Area Network).Ethernet can also be wireless where in this case it's "IEEE 802.11".
This was my networking tutorial, until then
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