1.0x

Parameters

Window size
Propagation time. Packet length is assumed to be constant and equal to one time unit. Round trip time is 2a + 1 = 7.
Block error rate; probability that a single packet is transmitted with errors and cannot be recovered

Animation

Press Start to start the simulation.

Description

When a simulation starts, the transmitter sends a packet to the receiver every time unit unless its window is full, i.e. there are W unacknowledged packets in the queue.

Following assumptions and simplifications are made in this simulation:

  • Packet length is constant and equal to one time unit.
  • Errors are independent and identically distributed.
  • The sequence number of a packet is not corrupted by errors.
  • Processing time is zero. For instance, as soon as the receiver receives a packet, it immediately sends back an ACK or NAK packet. The transmitter also operates this way.
  • ACK and NAK packet lengths are equal to zero and always sent error-free.

Legend

Node named Name
Packet with a sequence number of SN
Erroneous packet with a sequence number of SN
ACK packet acknowledging the packet with a sequence number SN
NAK packet requesting the packet with a sequence number SN
SN min Sequence number of the first unacknowledged packet
SN max Sequence number of the last packet that can be sent without further acknowledgement from the receiver. The difference between SN min and SN max is the window size.
SN next Sequence number of the first unsent packet