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Selective Repeat is part of the automatic repeat request (ARQ). With selective repeat, the sender sends a number of frames specified by a window size even without the need to wait for individual ACK from the receiver as in Go-Back-N ARQ. The receiver may selectively reject a single frame, which may be retransmitted alone; this contrasts with ...
Go-Back-N ARQ is a specific instance of the automatic repeat request (ARQ) protocol, in which the sending process continues to send a number of frames specified by a window size even without receiving an acknowledgement (ACK) packet from the receiver.
The Transmission Control Protocol uses a variant of Go-Back-N ARQ to ensure reliable transmission of data over the Internet Protocol, which does not provide guaranteed delivery of packets; with Selective Acknowledgement (SACK), it uses Selective Repeat ARQ. IEEE 802.11 wireless networking uses ARQ retransmissions at the data-link layer. [1]
The extremely popular HDLC protocol uses a 3-bit sequence number, and has optional provision for selective repeat. However, if selective repeat is to be used, the requirement that w t +w r ≤ 8 must be maintained; if w r is increased to 2, w t must be decreased to 6. Suppose that w r =2, but an unmodified transmitter is used with w t =7, as is ...
Three types of ARQ protocols are Stop-and-wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ. ARQ is appropriate if the communication channel has varying or unknown capacity, such as is the case on the Internet.
Selective repeat is a connection oriented protocol in which both transmitter and receiver have a window of sequence numbers. The protocol has a maximum number of messages that can be sent without acknowledgement. If this window becomes full, the protocol is blocked until an acknowledgement is received for the earliest outstanding message.
Stop-and-wait ARQ, also referred to as alternating bit protocol, is a method in telecommunications to send information between two connected devices. It ensures that information is not lost due to dropped packets and that packets are received in the correct order. It is the simplest automatic repeat-request (ARQ) mechanism.
Reliable Data Transfer is a topic in computer networking concerning the transfer of data across unreliable channels. Unreliability is one of the drawbacks of packet switched networks such as the modern internet, as packet loss can occur for a variety of reasons, and delivery of packets is not guaranteed to happen in the order that the packets were sent.