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07: Transport layer - Connectionless and unreliable service part 4


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After being introduced to connection-oriented communication, it is crucial to know another type of connection which is connectionless. This type of connection is totally different from the previous one because of the fact that it is unreliable. It uses none of the the characteristics of connection-oriented communication. This type of connection is not given due regard in CCNA curriculum, however, I will cover it on the grounds of its equal importance in networking.

As we said, in connectionless communication, there is no flow control to insure data integrity and delivery. In this connection the sender just transmits datagrams to the receiver, without even making sure that this latter has successfully received the datagrams. To put it another way, both end points ( the sender and receiver) communicate without prior arrangement. The device at one end of the communication transmits data to the other, without first ensuring that the recipient is available and ready to receive the data.

An example of this type of connection is live broadcast. Let us assume that you are watching something online – let it be a documentary, film, video clip, or anything else – (but it must be live), and suddenly after few minutes the broadcast cuts off for two seconds. Can you repeat the scence you were watching at that moment ? absolutely no. In live broadcast, you cannot repeat a scene if the sound or image was not clear. Your are there just to watch not to intervene, because in connectionless communication  the data segments are just transmitted to the destination and not acknowledgments is expected.

UPD (User Datagram Protocol) is a connectionless protocol. It is used in transmission that is deemed to be connectionless. By using this protocol, the sender does not care if the recipient receives all datagrams intended for transmission.

To sum up, connectionless communication does not require a session to be established between the sender and receiver. This service is not as reliable as connection-oriented one, but, importantly, it is much faster than this latter. It is rather useful in situations when data has to be transmitted in high speed. As shown in the example above, for a live broadcast to be comfortable, it must be fast. So, in this case, UDP protocol is opted for even though it is unreliable. Let us face it, in live broadcast, we do not need the transmission to be reliable because it may be just something insignificant to watch unimportant data which is obliged to be carried by a secure and reliable protocol, as TCP. For instance, if you are downloading a software, you cannot be pleased with half of the software if the the other part is not received due to a cut in connection.
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07: Transport layer - Connectionless and unreliable service part 4 Reviewed by BOUFTIRA on 7:39:00 AM Rating: 5

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