I need help answering these Six questions? Q1. Use the following picture, please

Question

I need help answering these Six questions?

Q1. Use the following picture, please explain how to make data transfer through unreliable channel reliable.

Q2. List two cases of unreliable data transfer.

Q3. When using acknowledgement for recovering errors during data transfer, why a sequence number is needed for data segment? Please explain!

Q4. What are the two acknowledgement methods most used in pipelined data transfer? Please explain how each of them work!

Q5. Please explain the data segment structure used in TCP protocol.

Q6. Please explain the relationship between TCP and IP.

O CD sending receiver rocess process data data f rdt send Iata data deliver data reliable channel reliable data reliable data transfer protocol transfer protocol (sending side) receiving side) udt send t packet packet rdt rcv unreliable channel (a) provided service (b) service implementation

Explanation / Answer

1. It is the responsibility of a reliable data transfer protocol to implement this service abstraction. The sending side of the data transfer protocol will be invoked from above by a call to rdt_send(). It will be passed the data to be delivered to the upper-layer at the receiving side. (Here rdt stands for ``reliable data transfer'' protocol and _send indicates that the sending side of rdt is being called.

Reliable Data Transfer over a Perfectly Reliable Channel,

Reliable Data Transfer over a Channel with Bit Errors.

Reliable Data Transfer over a Lossy Channel with Bit Errors are the three methods by which we can transfer data through through unreliable channel.

2. Unreliable protocols make no effort to set up a connection, they don't check to see if the data was received and usually don't make any provisions for recovering from errors or lost data. Unreliable data transfer is setup faster connections as it has less overhead when compared with TCP.

3. Adding a new field to the data packet and have the sender number to its data packets by putting a sequence number into the sender side data packets. The receiver then need only check this sequence number to determine whether or not the received packet is a retransmission. Thus adding a sequnce number usefull in retransmission.

4. Go-Back-N and selective repeat are the two acknowledgement methods most used in pipelined data transfer

In a Go-Back-N (GBN) protocol, the sender is allowed to transmit multiple packets (when available) without waiting for an acknowledgment, but is constrained to have no more than some maximum allowable number, N, of unacknowledged packets in the pipeline.

The GBN protocol allows the sender to potentially fill the pipeline with packets, thus avoiding the channel utilization problems we noted with stop-and-wait protocols. There are, however, scenarios in which GBN itself will suffer from performance problems.

5. TCP segments are sent as internet datagrams. The Internet Protocol header carries several information fields, including the source and destination host addresses [2]. A TCP header follows the internet header, supplying information specific to the TCP protocol. This division allows for the existence of host level protocols other than TCP. It contains

Source Port: 16 bits; Destination Port: 16 bits; Sequence Number: 32 bits; Acknowledgment Number: 32 bits; Data Offset: 4 bits

6. TCP works with the Internet Protocol (IP), which tells how computers transmit packets of data to each other. We can say, the Internet is defined by two fundamental rules TCP and IP. Internet protocol has the responsibility of sending data to the physical layer of the network. Like TCP, it adds a header to the data, or a string of 32 octets grouped in 32-bit increments called the IP address. The source packet has destination address for the destination in IP protocol. The TCP protocol works with the logical addresses amd helps the packets to reach their destination.

  

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