The company MEGAMIL S.A. wishes to install a point-to-point communications link between two of its branches operating at 10Mbps.

Two options are available:

a) Installation of a line characterized by a propagation delay of 50 microseconds, with a flow control mechanism based on stop and wait

b) Installation of a line characterized by a propagation delay of 250 microseconds, with a flow control mechanism based on a sliding window.

The number of bits used for frame numbering is 3 bits. Information and control frames require a 48-bit control header. Data frames contain 1000 data bits. We wish to determine the criteria for using one link or another for different scenarios. To do this, considering the probability of bit error on both lines negligible,

Determine: 1. The efficiency of the line based on stop-and-wait. Consider the number of erroneous frames in the network to be negligible.

2. The size of the window for which there is continuous sending considering the second option.

3. Criteria for the use of one line or another that maximizes the efficiency of frame transmission over the link.

4. Considering the above criteria and assuming that we compare both links for window size 3, represent the exchange of 7 frames, considering that the 4th frame is lost in the first transmission.

Represent the frame exchange only for the more efficient link. Choose an error recovery mechanism depending on the link considered. Represent only the exchange of data and control frames until the indicated frames are transmitted, without the need to represent control frames for link establishment and release.