ROOM 123

SECTION 1 | DATA PACKETS

​

​Before looking at how data is carried it is important to understand the principles of how the internet works so you understand the need for data transmission. The internet is a series of networks, servers and clients connected together using protocols and infrastructure to allow smooth data sharing on a global scale. Most data is currently transmitted from one device to another through the use of cables, even with your mobile phone, although the data is transmitted a short distance wirelessly the majority of the journey will be through cables.

 

Video: A Packet’s Tale. How Does the Internet Work

 

Data transmission is the process of sending information from one device to another over a network. To ensure efficient and reliable data transmission, the data is broken down into smaller units called packets. Each packet contains a portion of the data, along with a header that contains information about the packet, such as its source and destination addresses, and the sequence number of the packet.

 

When the packets are transmitted, they are sent individually and can take different routes to reach their destination. At the receiving end, the packets are reassembled into the original data. The header information is used to ensure that the packets are received in the correct order and to check for any errors or lost packets during transmission. If a packet is lost or corrupted, it can be retransmitted, ensuring the integrity of the data. This process of breaking down data into packets and transmitting it over a network is called packet switching.

 

SECTION 2 | PACKET STRUCTURE

​

A data packet is a small unit of data that is transmitted over a network. It consists of three main parts: header, payload, and trailer.

 

Header:

The header is a collection of information about the packet, such as the source and destination addresses, sequence number, and packet type. It also includes information about routing and error detection, such as checksum values.

 

Payload:

The payload is the actual data that is being transmitted. It can be a small amount of text, an image, a video, or any other type of digital information.

 

Trailer:

The trailer contains error correction information, such as cyclic redundancy check (CRC) values. The trailer helps the receiving device to verify the integrity of the data in the packet and to detect any errors that may have occurred during transmission.

 

Together, the header, payload, and trailer form a complete packet, which is sent over a network from one device to another. At the receiving end, the information in the header is used to reassemble the packets into the original data, while the trailer information is used to verify the accuracy of the data.

 

SECTION 3 | PACKET SWITCHING

​

Packet switching is the process of transmitting data over a network by breaking it down into small units called packets. The process involves the following steps:

 

Data is broken down into packets: The data to be transmitted is divided into smaller units, each containing a portion of the data and a header with information about the packet, such as its source and destination addresses.

 

Each packet could take a different route: When the packets are transmitted, they may take different routes to reach their destination. This is because the network routes each packet independently based on the current network conditions, such as traffic levels, to optimize for efficiency and reliability.

 

A router controls the route a packet takes: A router is a device that connects different networks and routes packets to their destination. It decides which route to send each packet based on information in the header and current network conditions.

 

Packets may arrive out of order: Because packets may take different routes, they may arrive at their destination in a different order than they were sent. This is because different packets may take longer or shorter routes based on network conditions.

 

Once the last packet has arrived, packets are reordered: After all the packets have arrived at the destination, they are reassembled into the original data. The header information is used to determine the correct order of the packets and to ensure that all packets have been received. If any packets are missing or corrupted, they can be retransmitted, ensuring the integrity of the data.

 

In conclusion, packet switching is a technique for transmitting data over a network by breaking it down into smaller units, routing each packet independently, and reassembling the packets at the destination to form the original data.

 

SECTION 4 | PROTOCOLS

​

Protocols are necessary for communication between devices and for the operation of computer networks. They provide a standardized set of rules and procedures for transmitting data over a network, allowing devices to communicate with each other in a consistent and reliable manner.

 

Here are some key reasons why protocols are necessary:

​

• Compatibility: Protocols ensure that devices from different manufacturers can communicate with each other effectively, regardless of their technical specifications or capabilities. This allows businesses and individuals to use a wide range of devices and software from different vendors and to integrate them into their existing networks with minimal effort.

• Efficiency: Protocols define the most efficient and effective way to transmit data over a network, reducing delays, errors, and other inefficiencies that can impact network performance.

• Reliability: Protocols provide a consistent and reliable way to transmit data, ensuring that it is delivered to the correct destination and in the correct order. This reduces the risk of data loss, corruption, and other errors that can occur during data transmission.

• Security: Protocols define security measures and protocols that can protect networks from attacks and unauthorized access. This includes encryption, authentication, and other security features that help ensure the privacy and security of network communications.

• Innovation: Protocols help drive innovation by providing a standardized framework for new technologies and solutions. By providing a common set of rules and procedures, protocols can spur the development of new applications, services, and devices that can improve network performance and functionality.

 

Protocols are necessary for the effective operation of computer networks, providing a standardized set of rules and procedures for transmitting data over a network. By ensuring compatibility, efficiency, reliability, security, and innovation, protocols help ensure that networks are robust, secure, and flexible, and can meet the needs of users and stakeholders over time. 

 

It is necessary for protocols to set provide a standard set of rules for the following:

​

• Data integrity: For the accuracy, consistency, and reliability of data as it is transmitted over a network. Data integrity can be compromised by errors or corruption that occur during transmission, such as missing or duplicate data. To ensure data integrity, various techniques such as error checking and redundancy can be used to detect and correct errors in data transmission.

• Flow control: For the process of managing the rate of data transmission to prevent overload or congestion on a network. Flow control mechanisms such as buffer management, windowing, and rate limiting can be used to regulate the rate of data transmission and prevent bottlenecks and congestion on the network.

• Deadlock: In a situation where two or more devices or processes are unable to proceed because they are waiting for each other to release a resource or complete a task. Deadlocks can occur on a network when multiple devices or processes are competing for the same resources, such as a shared database or file.

• Congestion: In a situation where the amount of traffic on a network exceeds its capacity, resulting in slow or delayed transmission of data. Congestion can occur due to various factors such as bandwidth limitations, network topology, or user behavior. To manage congestion, various techniques such as traffic shaping, packet prioritization, and congestion avoidance can be used.

• Error checking: For the process of detecting and correcting errors in data transmission to ensure data integrity. Various error checking techniques such as checksums, parity bits, and cyclic redundancy checks can be used to detect errors in data transmission and take corrective actions, such as retransmission of data.

 

Data integrity, flow control, deadlock, congestion, and error checking are all important concepts in networking that are critical for ensuring reliable and efficient transmission of data over a network. By understanding these concepts and implementing appropriate techniques and mechanisms, network administrators can optimize network performance and ensure that data is transmitted accurately, reliably, and securely.

 

SECTION 5 | TRANSFER SPEED FACTORS

​

The speed of data transmission across a network can vary due to several factors that can affect the performance of the network. Here are some of the key reasons why the speed of data transmission can vary:

​

• Bandwidth: The bandwidth of a network refers to the maximum amount of data that can be transmitted over the network in a given time period. If the bandwidth of a network is limited, then the speed of data transmission will be slower. Bandwidth can be limited by the network infrastructure, the type of connection being used, or other factors.

• Network Congestion: Network congestion occurs when the volume of data being transmitted on a network exceeds its capacity, resulting in delays and slower speeds. This can happen during peak usage times, when large numbers of users are accessing the network simultaneously.

• Distance: The distance between devices on a network can also affect the speed of data transmission. Data transmitted over longer distances may experience more delays and slower speeds due to factors such as signal attenuation, interference, and other issues.

• Network Type: The type of network being used can also affect the speed of data transmission. For example, wired networks such as Ethernet can typically provide faster speeds than wireless networks such as Wi-Fi, due to the physical limitations of the transmission medium.

• Network Devices: The performance of network devices such as routers, switches, and modems can also affect the speed of data transmission. Older or slower devices may not be able to handle large volumes of data, resulting in slower speeds.

 

The speed of data transmission across a network can vary due to factors such as bandwidth, network congestion, distance, network type, and network devices. By understanding these factors, network administrators can take steps to optimize network performance and ensure that data is transmitted as quickly and efficiently as possible.

 

SECTION 6 | DATA COMPRESSION

​

Data compression is often necessary when transmitting data across a network because it can reduce the amount of data that needs to be transmitted, resulting in faster transmission times and more efficient use of network resources. Here are some of the key reasons why data compression is necessary:

​

• Bandwidth optimization: Compressing data reduces the size of the data being transmitted, allowing it to be sent over a network using less bandwidth. This is particularly important when transmitting large files or data sets, as it can help avoid network congestion and delays.

• Storage optimization: Compressed data requires less storage space than uncompressed data, which can be useful when storing large volumes of data on servers or other storage devices. This can help reduce the cost and complexity of storage solutions, particularly for businesses and organizations that deal with large amounts of data.

• Cost savings: Compressing data can help reduce the cost of transmitting data over a network, particularly for businesses and organizations that rely on expensive leased lines or other high-speed connections. By reducing the amount of data that needs to be transmitted, organizations can save money on network infrastructure and connectivity costs.

• Improved user experience: Compressing data can improve the user experience for individuals and organizations by reducing the time it takes to transmit data, particularly over slow or congested networks. This can help improve productivity and reduce frustration for users who rely on network-based applications and services.

 

Data compression is often necessary when transmitting data across a network because it can reduce the amount of data that needs to be transmitted, resulting in faster transmission times, more efficient use of network resources, and cost savings. By using compression techniques such as lossless or lossy compression, organizations can optimize their networks and improve the user experience for individuals and businesses.

 

SECTION 7 | WIRES, CABLES AND WIRELESS

​

​When talking about data transfer we mean the transfer of binary digits 1s and 0s, these are represented by electrical signals or pulses of light or radio waves. Currently nearly all data transferred from one device to another are sent via cables. Even if your device is wireless, the wireless part of the data transmission is usually just a short distance. Many cables are laid all over the world and under the oceans. Copper cables generally carry the data over short distances and optical cables over long distances.

 

Video: The Internet: Wires, cables & Wifi

 

SECTION 8 | CABLE TYPES

​

There are three main mediums through which data is transferred over networks:

​

• Optical Cable

• Copper Cable

• Wireless

 

The copper cables can be broken up into two main categories; coaxial cable and twisted pair. Although coaxial cable is not often the first choice of cable it has been very useful in the development of networks because a large amount of coaxial cable had previously been installed for other purposes and has formed a quick fix as network technologies have developed. Twisted pair cable is mainly used in local area networks as it is relatively cheap to buy and quite robust which makes installation within buildings easy. Optical cable is expensive to buy however it has very fast data transfer rates, therefore it is the cable of choice for long distance data transfer.

 

OPTICAL CABLE

Made from many strands of optical fiber, it is used for long distance data transfer or where speed is critical.

 

Advantages:

​

• Very fast data transfer

• Difficult to hack

• Not susceptible to interference

• High bandwidth capabilities

 

​Disadvantages:

​

• Expensive to buy

• Data corruption over a short distance so it needs repeaters - signal spreading with distance thus limiting how closely data can be packed without overlapping

 

 

COPPER TWISTED PAIR

Currently often referred to as Cat 5 cable. It has pairs of copper twisted cable, they are twisted to reduce interference, it also has an aluminum shield and a drain wire. Cat 6a cable has a high bandwidth. (UTP- Unshielded Twisted Pair)

 

Advantages:

​

• Low cost

• Popular use makes it an easy compatible option with no bridge required.

​

Disadvantages:

​

• Older Cat rated cable has a low bandwidth

• It can be affected by interference

• It needs repeaters when used for long distances

• It is easy to hack

 

Crosstalk is interference from one cable to another. Because cables often run in the same cable trunking and run parallel to each other crosstalk is able to happen. Using twisted pairs of wires and shielded twisted pairs of wires helps minimize this effect. 

​

COAXIAL CABLE

A single copper cable covered with a dielectric insulator and a metallic shield then a plastic sheaving.

 

Advantages:

​

• Many pre-installed cables could be used to initially develop networks

• It is not very susceptible to interference

• High frequency range

 

Disadvantage:

​

• Cost for performance ratio is not good

• It is easy to hack

• Susceptible to damage and lightning strikes