SIT202 Computer Networks

it can be seen that it a diagram showing a communication among client and server computer. The cookie is stored on a server and generate a session on the client side also. Let us go through the scenario events to make us understand better.

Step 1

In the first step, the client computer queries the besttoys.com webpage in order to establish a link for prolonged communication. In response, the web server generates a cookie file on webserver providing it with a unique ID, for instance in our case scenario, the number is ID 12343.

Step 2

In the second step, the cookie is created with a unique ID identifier. The ID in this case is ID 12343. The server will respond to the client on the basis of the generated identifier with the client query. 

Step 3

In this step, the client will generate a cookie. The cookie generated by the client has the similar ID as the server. For example, the client will generate a cookie on its side to for the purpose of future communication. In case there are future communications, ID 12343, will be in use.

Step 4

In the fourth step, the client computer will receive a response from the server computer. The response contains the queried price by client in step three above. Additionally, the response also contains the update cookie together with the last enquiry requested by client computer.    

Step 5

In step five, the payment has to be made by client computer and send to the server computer together with data information concerning payment amount besides product data with client computer cookie ID. Payment amount may include information such as currency, amount, modes of payment etc. while product information may include quantity requested, product availability, etc.

Step 6

This is the final step. In the step six, the server sends to the client computer a final confirmation. The confirmation concerns client’s receipt of payment of the product order that was placed. The cookie ID is updated on server computer (Experts, 2017 ).  

Question 1.B

In the above diagram, I have drawn the same scenario using Microsoft Visio modelling tool. From the image, Deakin University is the major intermediary between the advertising company and the webpage manages guest cookie. The website after it generates the cookie, the created cookie’s copy then is sent to the manufacturing company. The cookie copy sent to the manufacturer company contains guest’s information who visits the Deakin website and clicks on the links present (Shetty, et al., 2015 ).

Question 2

TCP connection Establishment and connection

Establishment of connection

For a connection to be established, TCP deploys 3-way handshake. In advance before the client computer attempts to create a connection with server side, the server has to bind and guarantee to listen to the port to exposed it for interlinks. This known as inactive open. After the inactive open has been created, the client may recruit the active open.to have a link, the 3-route handshake has to take place as shown below:

• SYN: the participating open is done by client computer releasing a SYN to a server computer. The client computer generates seven times.
• A SYN-ACK: in reply with SYN-ACK. The ACK number is generated (i.e. A+1), the server selects another unique sequence number say B.
• ACK: lastly, the client PC succeeds an acknowledgement from server. Categorization number is set to receive ACK value (i.e. X+1). The ACK figure is incremented 1 more than the received sequence number.

At this moment, both the server and the client have received an ACK of interlinking. Step 1 and 2 establishes a connection parameter for unidirectional and its acknowledgement. The final two steps (2 and 3) launch connection parameter (i.e. categorization number) for other direction and it’s approved. With the full-duplex events, the communiqué is launched (Vacca, 2012).

Ending a connection

The connection end process deploys a four way handshake. It is worth to note that each side of connection terminates independently. In case any of the endpoint device wish to bring to an end half of its connection, it sends an acknowledgement and FIN packet to the other end device. The opposite end recognizes with an ACK. Thus, a classical closure requires the pair of ACK and FIN segments from every TCP end part. Once both ACK/FIN interactions have been determined, the end that send FIN before receipting one has to wait for timeout beforehand the connection is closed down. Throughout this period, the native port is not available for fresh connections. This inhibits misperception since delayed packet are delivered in successive connections.

A link may be half-open that is, one end side ended its end but opposite has not terminated. The end that has ended the connection can never send any form of information in the link. However, the other side can send information to the other end. The terminated side has to remain evaluating the information till the opposite end ends too.

In addition, it is potential to end the link by a three-way handshake, let us say, when node 1 sends a FIN and node 2 responds with a FIN and an acknowledgement and host 1 responds back with an acknowledgement.

However, it may occur coincidently that node A and host B send out a FIN simultaneously, both ends have an ACK. This is considered as a two-way handshake. This is so because, FIN/acknowledgement sequence has been accomplished in parallel for both endpoints.

It is important to mention that some host TCP stacks do not put in practice half-duplex close series. The applications include but are not limited to HP-UX and Linux. In case these hosts closely connection actively without reading incoming data, the hosts have to a RST instead of use of the FIN. This assures the TCP application that the remote computer has gone through all data the previous device sent. The local device waits for FIN from the remote computer. Since the remote computer cannot differentiate between data Loss RST and a connection aborting RST, both throw away all information that was received (Odom, 2013).  

References

Experts, D., 2017 . Computer Knowledge for SBI/ IBPS Clerk/ PO/ RRB/ RBI/ SSC/ Railway. 2nd ed. New Delhi: Disha Publications .

Odom, W., 2013. CCENT/CCNA ICND1 100-101 Official Cert Guide. Indianapolis: Cisco Press.

Shetty, N. R., Prasad, ‎. & Nalini, ‎., 2015 . Emerging Research in Computing, Information, Communication. 1 ed. Salmon Tower Building New York City: Springer.

Vacca, J. R., 2012. Computer and Information Security Handbook. London : Newnes.