#Week 2. 2 technologies in the history of the Internet that paves the way to today's reality

 

For the second week task, I will talk about 2 technologies in the history of the Internet such as Aloha that has become obsolete and Ethernet technology that is currently used even though the media used has evolved.

First of all, I think it is important to remark that the World Wide Web didn’t come up from nothing but it was the result of multiple steps forward, out of the necessity, to search for solutions to unsolved problems. 

Therefore, for instance the ARPANET group wanted to provide remote access to their main computer  system and they were using telephone lines to do so.


  By other hand, The system known as Aloha and created by Norman Abramson wanted to do it through shared radio network to overcome the terrain barriers and being able to communicate between the different islands in the Hawaii Archipelago. I took this example as a technology that is no longer used even though it inspired the new wireless technologies that are valid today. The main idea is that terminals can transmit their data regardless of the activity of other terminals. If a message is successfully received, the base station sends an acknowledgement back over the feedback channel. If the acknowledgement is not received, then the message is retransmitted after waiting a random time. With many users involved, the number of collisions will also dramatically increase, which will require retransmission and therefore decreasing the throughput and even collapsing the media.
As an improvement to the original Aloha, the protocol "Slotted ALOHA" was created and increased the maximum throughput by introducing discrete timeslots. A station can only start a transmission at the beginning of a timeslot. 



Unlike the ARPANET where each node could only talk directly to a node at the other end of a wire or satellite circuit, the fact that it used a shared media, generated a considerable interest and several projects were initiated thanks to the idea. Among those I can highlight the Ethernet, that is still operative. Unlike the Aloha system, in which transmitters could not receive any signals, Ethernet stations could detect that collisions had occurred, stop transmitting immediately, and retry a short time later (at random). Ethernet was at first used to connect around 100 computers in Palo Alto (EEUU) and with the help of David Clark’s group at MIT, built an efficient TCP implementation which led to the proliferation of PCs connected by LANs and increasing the size of Internet.

Ethernet is one of two LAN technologies used today, with the other being wireless LANs (WLANs). Ethernet uses wired communications, including twisted pair, fiber-optic links, and coaxial cables.

Ethernet operates in the data link layer and the physical layer. It is a family of networking technologies defined in the IEEE 802.2 and 802.3 standards.

Find here below the sources used for this entry:

  1. https://www.nap.edu/read/6323/chapter/9#175
  2. https://www.clear.rice.edu/comp551/papers/Abramson-Aloha.pdf
  3. https://www.researchgate.net/figure/Example-of-SIC-enabled-slotted-ALOHA-Packet-2-is-received-in-singleton-slot-3-enabling_fig3_309551186
  4. http://www.wirelesscommunication.nl/reference/chaptr06/aloha/aloha.htm
  5. Networking Academy CCNAv7 curriculum, Introduction to Networks (ITN)




Comments

Post a Comment

Popular posts from this blog

#Week 5. The Case for Copyright Reform Task

For this week I will give my opinion about the book  The Case for Copyright Reform . The book and particularly chapter 2 is trying to convince readers that the copyright as it’s been conceived, it is not good for society because if it is going to be applied effectively, it will collide with fundamental rights and they are advocating for a modification. When the author say that this copyright law is endangering fundamental rights, it means that if you really want to avoid people sharing digital files, you need to sniff the communication between them and see what kind of information they are exchanging which of course lead you to know everything else if you want to.   That is a difficult debate. If you think that you are harming an author you admire,  most of the people will be in favour of a tough copyright law. By other side, If you think that this law is attempting against your fundamental rights and that it is not protecting the author but the industry and all the people that was use
Read more

#Week 13 About Linux Distributions. Debian and Slackware.

 This week I will talk about the different lynux distributions. First question I made myself and I think it is understandable, is why so many distributions are   available ? The answer is simple and it is to better suit your needs because of the applications you are supposed to run. Some distros are geared towards user entertainment and may include all of the programs necessary to reproduce video and audio, in any format (including owners), others are more oriented to games  others to security, some to science, others to education, etc. (Target of the software). Apart from that, that I think is the main reason due to the easiness of the software to create custom distributions, there are other reasons such as the use or not of open code even when it holds copyleft license (I think this is mainly when the distribution  is run through a server). Given the fact that there are a few hundred distributions and many are even to be released, and like each one of these has both advantages and di
Read more

# Week 11. Example of censorship and privacy in today's society

On this week’s blog, I will talk about one curious case about censorship and another concerning privacy when it comes to fight organized crime or terrorist groups.  Regarding censorship I will talk about the Streisand effect. The singer Barbara Streisand gives the name to this social phenomenon that occurs when a censorship intention has the unintended effect of propagating further the event that is trying to hide. The term alluded to Barbra Streisand, who in 2003 sued photographer Kenneth Adelman for distributing aerial pictures of her mansion in Malibu. But Adelman was no paparazzo—he operated the California Coastal Records Project, a resource providing more than 12,000 pictures of the California coast for scientists and researchers to use to study coastal erosion. Of course, news outlets around the world reported on Streisand’s outrage, and before long, the photo on Adelman’s website (below) had received well over a million views. At the end it was a calamity for the artist because
Read more