What is Go back N sliding window protocol?

What is Go back N sliding window protocol?

Go-Back-N protocol, also called Go-Back-N Automatic Repeat reQuest, is a data link layer protocol that uses a sliding window method for reliable and sequential delivery of data frames. It is a case of sliding window protocol having to send window size of N and receiving window size of 1.

What is Go back N and Selective Repeat protocol?

Go-Back-N Protocol. Selective Repeat Protocol. 1. In Go-Back-N Protocol, if the sent frame are find suspected then all the frames are re-transmitted from the lost packet to the last packet transmitted. In selective Repeat protocol, only those frames are re-transmitted which are found suspected.

What will be the size of Go back N sender sliding window If the sequence number is 4?

Solution: Here, GB4 means that N is equal to 4. The size of the sender’s window is 4. Step 1: As the window size is 4, so four packets are transferred at a time, i.e., packet no 1, packet no 2, packet no 3, and packet no 4.

How do you calculate window size in back n?

Go-Back-N the maximum window size is: w= 2^m -1 w=255. Selective Repeat the maximu window size is: w=(2^m)/2 w=128.

What is the efficiency of the go back n protocol?

Differences:

What are the advantages of Go-Back-N ARQ?

It can send multiple frames at once. 2. Pipelining is present in the Go-Back-N ARQ i.e. a frame can be sent by the sender before receiving the acknowledgment of the previously sent frame. This results in a lesser waiting time for the frame.

What is difference between stop wait and Go-Back-N?

Difference between Stop and Wait, Go-Back-N, and Selective Repeat. The Sender window size in the Stop and Wait protocol is 1. The Sender window size in the Go-Back-N protocol is N. The Sender window size in the Selective Repeat technique is N.

Why the window size of Go-Back-N is not 2m or greater?

We can now show why the size of the send window must be less than 2m. If the size of the window is 3 (less than 22) and all three acknowledgments are lost, the frame 0 timer expires and all three frames are resent. The receiver is now expecting frame 3, not frame 0, so the duplicate frame is correctly discarded.

What is the minimum window size required for Go-Back-N ARQ?

In Go-Back-N ARQ, the size of the send window must be less than 2m; the size of the receiver window is always 1. Stop-and-Wait ARQ is a special case of Go-Back-N ARQ in which the size of the send window is 1. In Selective Repeat ARQ, the size of the sender and receiver window must be at most one- half of 2m.

What is the size of receiver window in Go-Back-N ARQ?

equal to 1

The size of the receiver window in Go Back N ARQ is equal to 1. When the acknowledgment for one frame is not received by the sender or the frames received by the receiver are out of order, then the whole window starting from the corrupted frame is retransmitted.

Why is it called Go-Back-N?

The receiver accepts packets only in sequence; it does not buffer packets received out of order. Consequently, if the transmitter sends N packets and if the first is lost, then it must resend all the N packets starting from the first one. Hence the name Go-Back-N.

What is minimum window size required for Go-Back-N ARQ protocol?

Where is Go-Back-N ARQ used?

data flow control purposes
Go Back N ARQ which stands for Go Back N Automatic Repeat Request (ARQ) is a data link layer protocol that is used for data flow control purposes. It is a sliding window protocol in which multiple frames are sent from sender to receiver at once.

What is the disadvantages of go back n protocol?

Disadvantages

• Timeout timer runs at the receiver side only.
• The transmitter needs to store the last N packets.
• The retransmission of many error-free packets follows an erroneous packet.

Why the window size of Go Back N is not 2m or greater?

Why is sliding window better than Stop and Wait?

In Stop and Wait protocol, sender sends single frame and waits for acknowledgment from the receiver. In Sliding window protocol, sender sends multiple frames at a time and retransmits the damamged frames. Stop and Wait protocol is less efficient. Sliding Window protocol is more efficient than Stop and Wait protocol.

How do you calculate window size in back and ARQ?

Window size for Go-Back-N ARQ

1. We choose m = 2, which means the size of the window can be 2m – 1, or 3.
2. If the size of the window is 3 (less than 22) and all three acknowledgments are lost, the frame 0 timer expires and all three frames are resent.

What is the maximum window size in sliding window protocol?

Maximum window size = 1 + 2*a where a = Tp/Tt Minimum sequence numbers required = 1 + 2*a. All the packets in the current window will be given a sequence number.

What is size of receiver side window?

1 in
Receiver Window Size (WR)
WR is always 1 in GBN.

Does TCP use Go back N?

This service department lies in the hands of TCP. Their major flow control protocols – Stop and Wait, Go Back N, and Selective Repeat. The sender sends the packet and waits for the ACK (acknowledgement) of the packet.

What is the efficiency of the Go back N protocol?

In Go-Back-N ARQ, N is the sender window size, which we can see in the above example was 5. Now, here N should be greater than 1 in order to implement pipelining. If N=1, then our system reduces to Stop & Wait protocol. Now the efficiency of Go-Back-N ARQ = N/(1+2a), where a = tp/tt.

What is receiver window size in Go-Back-N ARQ?

Why is the size of send window in Go-Back-N ARQ less than 2m?

What is the purpose of ARQ?

Automatic Repeat Request (ARQ) is an error-control mechanism for data transmission which uses acknowledgements (or negative acknowledgements) and timeouts to achieve reliable data transmission over an unreliable communication link.

What are the advantages and disadvantages of Go-Back-N protocol?

Using the Go-Back-N ARQ protocol leads to the retransmission of the lost frames after the expiry of the timeout timer.
…
Disadvantages

• Timeout timer runs at the receiver side only.
• The transmitter needs to store the last N packets.
• The retransmission of many error-free packets follows an erroneous packet.