In the presence of possibility of package loss, duplication and reordering, how do we handle connection establishment, connection termination, ensure ordering and reliability?
In the presence of possibility of package loss, duplication and reordering, we handle connection establishment, connection termination, ensure ordering and reliability by following ways:
Connection Establishment
To establish a connection, TCP uses a three-way handshake. Before a client attempts to connect with a server, the server must first bind to and listen at a port to open it up for connections: this is called a passive open. Once the passive open is established, a client may initiate an active open. To establish a connection, the three-way (or 3-step) handshake occurs:
Connection Termination:
At this point, both the client and server have received an acknowledgment of the connection. The steps 1, 2 establish the connection parameter (sequence number) for one direction and it is acknowledged. The steps 2, 3 establish the connection parameter (sequence number) for the other direction and it is acknowledged. With these, a full-duplex communication is established.
The connection termination phase uses a four-way handshake, with each side of the connection terminating independently. When an endpoint wishes to stop its half of the connection, it transmits a FIN packet, which the other end acknowledges with an ACK. Therefore, a typical tear-down requires a pair of FIN and ACK segments from each TCP endpoint. After the side that sent the first FIN has responded with the final ACK, it waits for a timeout before finally closing the connection, during which time the local port is unavailable for new connections; this prevents confusion due to delayed packets being delivered during subsequent connections.
A connection can be "half-open", in which case one side has terminated its end, but the other has not. The side that has terminated can no longer send any data into the connection, but the other side can. The terminating side should continue reading the data until the other side terminates as well.
It is also possible to terminate the connection by a 3-way handshake, when host A sends a FIN and host B replies with a FIN & ACK (merely combines 2 steps into one) and host A replies with an ACK.
Some host TCP stacks may implement a half-duplex close sequence, as Linux or HP-UX do. If such a host actively closes a connection but still has not read all the incoming data the stack already received from the link, this host sends a RST (losing the received data) instead of a FIN. This allows a TCP application to be sure the remote application has read all the data the former sent—waiting the FIN from the remote side, when it actively closes the connection. But the remote TCP stack cannot distinguish between a Connection Aborting RST and Data Loss RST. Both cause the remote stack to lose all the data received.
After session gets disconnected:
If there is a connection loss in transport layer and it is TCP/IP, would expect the session initiator to:
The sequence number to use on the logon message depends on the type of session and what has been agreed with the FIX session acceptor (see the spec for details). For sessions where there is no value in replaying any lot messages e.g. market data feeds where the prices would be stale, it makes sense to send a logon message with sequence number 1 and set tag 141=Y (to reset the sequence numbers). For an orders session, where message replay might be required, the session initiator should generally logon with a sequence number of one greater than the last message sent (and expect a logon response from the FIX session acceptor with sequence number of 1 greater than the last message received).
Unless you really need the message replay, it is cleaner and easier to reset the sequence numbers each time upon logon. This obviously depends on the FIX session acceptor (FIX server) support for this. For things like STP feeds, I've found this to be far more reliable and it is generally better for the application protocol to provide application level replay facilities rather than relying on the brittleness of FIX session replay.
In the presence of possibility of package loss, duplication and reordering, how do we handle connection...
How do we handle the non traditional family such as 2 dads or 2 moms? This might not be what we believe to be a traditional family, or it could be against our personal beliefs, so we have to make sure that we are not passing judgement. How can we do this as nurses?
If White people are privileged, how do we explain the presence of poverty among whites?
How do we expect the luxury package to affect price? Round to nearest whole number The dependent variable is the sales price of a used car. The independent predictor variables are and whether or not the car has a luxury package (yes 1, mileage 0). Answer questions 31 -32 no Regression Stetistics mileage luxury package salesprice 42,000 Multiple R 0.90 26,500 0.31 R 5qure 2 37,500 29,400 Adjusted R Square 0,78 41430 24,000 33,700 Standard Emor 3577.08 19,670 1 ODEervations...
What are the different kinds of chromosomal duplication, and how do they differ from each other? What human disorder results from deletion of a region on chromosome 5 producing newborns that cry like a cat? If Dr. Obama wishes to reveal regions of the chromosomes that are rich in A-T base pairs in a karyotype preparation, she should use ___ to stain G bands on the chromosomes. A typical human karyotype has a total of ___ chromosomes and includes ___...
If a payoff diagram shows a loss of $46 a a share, how much do we lose in total? A. $46.00 B. $460.00 C. $4,600 D. $46,000.00
Why do we want/need the presence of Mg2+ in a PCR but do not want it present at all other steps of processing/analyzing a DNA sample? (2 marks) Identify and explain what generally occurs in each of the 3 main steps of a polymerase chain reaction. (6 marks) 8. Identify and explain what the 3 different PCR controls inform you about the results of a PCR. (3 marks) Highlight the 2 advantages and 3 disadvantages of using PCR. Ensure to...
How can we assess whether a project is a success or a failure? This case presents two phases of a large business transformation project involving the implementation of an ERP system with the aim of creating an integrated company. The case illustrates some of the challenges associated with integration. It also presents the obstacles facing companies that undertake projects involving large information technology projects. Bombardier and Its Environment Joseph-Armand Bombardier was 15 years old when he built his first snowmobile...