Consider two computers $($Hosts A and B$)$ communicating using the HDLC protocol and employing

the Selective Reject Error Control technique with modulo eight numbering. The following

scenarios are to be explored using appropriate sequence numbers:

$($i$)$ Host A sends frame $I(5,2),I(6,2)$ and $I(7,2)$ to Host $B$ and all frames arrive intact. Identify

the next data frame from Host B to Host A$.$

$($ii$)$ Host B sends $I(1,4),I(2,4),I(3,4),I(4,4)$ and $I(5,4)$ to Host A$.$ One of these frames fails to

arrive causing Host A to respond immediately with SREJ$(3)$ which in turn results in a

response from Host B$.$ This last transmission from Host B arrives successfully at Host A

and no further transmissions are made at this point.

The following table $($Table $1-$ Incoming and outgoing buffers$)$ identifies three distinct

events on the top row. Below each event there are a number of cells representing the

contents of incoming and outgoing buffers on each host. Replicate the table in your answer

book. For each event, enter the appropriate frame numbers identified above into each cell.

If you believe there is nothing stored in a buffer simply enter the word 'Blank' in the

appropriate cell.

$(12$ marks$)$