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Communication Links and Packet Switching

As a part of line configuration in computer networks, communication links is actually a connection or transmission technologies that connects particular machine. This links enable the state/stations to communicate with each other. There will be 2 or more devices connected through a link. Those link is a communication link pathway that could transfer data from one device to another.There might be several terms like line configuration, types of connections, or communication links. But don't worry because they are same things with difference terminologies.

In computer networking, there are 2 types of communication links. Those are broadcast links and point-to-point links. As i said before this could be also has different terminologies such as point-to-point links and broadcast link.

Point-to-point Connection

Point-to-point Connection

According to its name, point-to-point connection means 2 state or devices (that represented by the point) provides a dedicated link for them to communicate. So the entire capacity of the link is used for tramsitting between 2 connected devices only. In a daily basis, you can figure how you move your photos from your phone to your computer. Most likely you are using a cable to connect 2 devices which are your phone and your laptop. And indeed, that is the simplest way to billustrate a point-to-point connection because it is recognized as one of the easievbfgst and most conventional network topologies. This connection can be established not only using wired connection (laptop and phone connection for data transfer) but also wireless connection (remote control and TV for changing channels).

Multipoint Connection

Multipoint Connection

Same like the previous connection, according to its name multipoint connection means there is a common link that connects every state in particular connection. So basically there will be more than 2 devices connected to a shared link. This will make the capacity of the connection is shared as well among connected state for trasmitting signal. Because it is a sharing connection, the sharing mechanism can be devided into 2 cases, spatial sharing and temporal or time sharing. Spatial sharing happened if several state or devices can share the link simultaneously. On the other hand, temporal sharing occur if users must take turns while using the link.

Packet Switching

Short Definition

The routing and transferring of data by means of addressed packets so that a channel is occupied during the transmission of the packet only, and upon completion of the transmission the channel is made available for the transfer of other traffic.

Unlike the circuit switching method that were used in old telephone lines, packet switching method segments the data that is going to be transferred into several packets containing the segmented data, IP address, and sequencing information. Then, these packets are transferred sequentially to the destination over the network. Using this method, a packet reserves only a path between two links, not the entire path from the sender and the receiver. Therefore, this method is more cost-effective and cheaper compared to the circuit switching. It also makes the network more efficient.

Each packet can travel through different path on the network. The path of each packet is the fastest path on that time based on the traffic and transmission quality of the channels. This mechanism enables the network to still be available even though there is a link that is down, more fault-tolerant.

Illustration of packet switching method

There are a case where received packets are not in the correct order as the preliminary segmented data. Therefore, the received machine system needs to sort the packets into the correct order and merge them back.

Packet-switched networks are more efficient and flexible than the circuit-switched networks because it does not to reserve the path until the connection is terminated. However, there is some amount of delay in packet switching, whereas circuit switching is better for transmitting real-time data.

Connection modes

Based on wikipedia, packet switching use a connectionless switching technique. In connectionless mode, a sender doesn't establish an agreement / a connection for sending the packet to a receiver. In connection-oriented mode, a sender has to establish an agreement for sending the packet to a receiver. Frequently, a packet transmitted in connectionless mode is called a datagram.

For example of connectionless mode, Ethernet protocol, IP (Internet Protocol), and UDP (User Datagram Protocol) are protocols with connectionless system. MAC Address in header of Ethernet protocol, IP address in header of IP, and Payload in header of UDP are called datagram. Those protocols don't have to establish a connection to receiver.

For example of connection-oriented mode, TCP (Transmission Control Protocol) is a protocol with connection-oriented system. In TCP protocol, a sender has to established a connection to a receiver with SYN-ACK-FIN packets or sometimes called 3-Way Handshake. So, before sending the packet to the receiver, the sender has to establish a connection with the receiver first.

Difference between TCP and UDP (This image is taken from https://sergeyzhuk.me/assets/images/posts/reactphp/tcpvsudp.jpg)

Packet Switched Network

The most famous implementation of packet switched network is ARPANET. ARPANET use packet switching mechanism to run TCP/IP protocol. There are a lot of packet switched networks, here is the list of some packet switched networks :

  • ARPANET
  • BNRNET
  • X.25 era
  • Euronet
  • IPSS

References

Mucins Weebly Wikis. (2018, February 15). 2.1 line configuration. Computer Networking Concepts. Retrieved February 25, 2021, from https://mucins.weebly.com/21-line-configuration.html

Boyini, K. (2018, September 28). Packet switching. RxJS, ggplot2, Python Data Persistence, Caffe2, PyBrain, Python Data Access, H2O, Colab, Theano, Flutter, KNime, Mean.js, Weka, Solidity. Retrieved February 26, 2021, from https://www.tutorialspoint.com/packet-switching

GeeksforGeeks. (2021, February 19). Packet switching and delays in computer network. Retrieved February 26, 2021, from https://www.geeksforgeeks.org/packet-switching-and-delays-in-computer-network/

National Telecommunication Information Administration. (1997). Telecommunications: Glossary of telecommunications terms. Government Institutes.

Sunny Classroom. (2017, July 12). Circuit Switching vs. Packet Switching [Video]. YouTube. https://www.youtube.com/watch?v=B1tElYnFqL8

Techopedia. (2017, February 2). What is packet switching? - Definition from Techopedia. Techopedia.com. Retrieved February 26, 2021, from https://www.techopedia.com/definition/5603/packet-switching

Weik, M. (2012). Fiber optics standard dictionary. Springer Science & Business Media.

Ramos-Escano; et al. (June 2, 2005). "US Patent Application Publication 2005/0117529 A1". Retrieved May 19, 2008.

Information Processing Systems - Open Systems Interconnection, "Transport Service Definition - Addendum 1: Connectionless-mode Transmission", International Organization for Standardization, International Standard 8072/AD 6, December 1986.

Wikipedia, packet switching from https://en.wikipedia.org/wiki/Packet_switching

Wikipedia, ARPANET from https://en.wikipedia.org/wiki/ARPANET