by irisxzy

Network Protocols and Packet Switching

Network Protocols

Protocol is a set of rules used to define a method of exchanging data over a computer network. Protocols have the following five basic functions:

  • Ensure data integrity.
  • Manage data follow. (It defines the order and format two tor more computers follow to communicate with each others)
  • Prevent deadlock. (Having deadlock is just like no one speak first in a conversation. Protocols decide the order.)
  • Manage congestion. (Since data packages travel between computing entities, protocols organize the traffic and direct the path of each package.)
  • Perform error checking (After packages arrive to their destination, protocols check whether all the requested packages have arrived without any missing.)

Two basic protocols used in computer network are TCP and IP.

Transmission Control Protocol (TCP) & Internet Protocol (IP)

Let’s imagine a scenario. I am trying to move my big piano to my new apartment. I need to break the giant piano into small parts, carry those small parts to my new apartment and resembled them in order. I ask EMS to deliver my piano components.

The breaking and reassembling work are similar with TCP’s job in computing network. TCP  software breaks messages into packets, hands them off to the IP software for delivery, and then reassembles the packets in order at their final destination. IP software’s job is similar to EMS. IP software delivery packages brought by TCP to the final destination.

High-level Protocols

High-level protocols are built upon TCP/IP.

picA2-feature-2.jpg(BENZCLOUD奔馳雲端 優質平價雲端服務)
  • Simple Mail Transfer Protocol (SMTP) rules the transmission of electronic mails. Its applications are  Gmail, Hotmail, etc.
  • File Transfer Protocol (FTP) allows transmission of files. Microsoft Exchange is a example of FTP server.
  • Telnet used to log onto one computer from a remote one.
  • Hyper Text Transfer Protocol (http) allows exchange of Web documents
    • Hypertext refers to the fact that data and information are not organized like bullet-point. You can actually add link to one information and jump from one page to another if needed, and that’s what hypertext means. 超链接

Packet switching

Datagram or Connectionless Packet Switching1.PNG(Datagram Or Connectionless Packet Switching)

Packet switching is a process that messages are divided into fixed-sized, numbered packets by TCP; then individually directed to their destination in different path, then reassembled at the final destination by TCP.

Steps for Package Switching

  1. Data split into packets by TCP.
  2. Each data packet has a from address, to address and payload
  3. The order of each packet is noted for future reassemble.
  4. Packets was sent onto the network. Routers assigned different path for each package. Since packages travel in different distance, they arrived at the final destination at different time and not in order. The more routers the more reliable data are.
  5. TCP supervise packages’ arrivals. TCP checks whether all packages has arrived. Once the integrity is confirmed, packages are re-ordered according to their original order.
  6. A message is sent from recipient to sender indicating that the message has been received
  7. If there is no confirmation message, sender will transmit data again.

Role Play

In the class, we participated in a role play game in silence. Students acted as nodes, IP delivers and routers and we are not allowed to speak. Sender node sent a package of information to receiver node and receiver node reply to sender node. The sender node first put the information in a package and write down the IP address of receiver on the package. Then the IP deliver take the package from the sender to router. The router’s job was to decide the path that the package went. Then IP deliver carry the package and follow the path to the receiver node. After the receiver node got the package, it took information out of the package, read it, and replied. Then the receiver repeated the same process to transfer the replying information to the sender.

This game is really useful for us to memorizing the package transmission process. I recommend you to play it with your friends! 🙂

Works Cited

“Datagram Or Connectionless Packet Switching”. Allsyllabus.com. N.p., 2016. Web. 20 Oct. 2016.

“BENZCLOUD奔馳雲端 優質平價雲端服務”. Benz-cloud.com. N.p., 2016. Web. 20 Oct. 2016.

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