1.
The length of IP header is 20 Bytes and the length of checksum is 2 Bytes.

n = 2 B
m * n = 18 B
m = 9 B

If we view the IP header as an m by n matrix, the matrix has 10 rows and 2B 
columns.

Recall that the parity bit in a column cannot detect an even number of 
corruptions in that column, but can detect an odd number of corruptions 
in the column.

a. No
If all bits in IP header are corrupted, then checksum cannot detect corruption
since all columns have an even number of corruptions.

b. YES 
If all bits in IP header, except one, are corrupted, then the checksum 
can detect corruption since one column has an odd number of corruptions.

2. 
process p
inp	d: array[integer] of integer
var	x: integer	  {index of d; init. 0}
begin
	true	--> send data(0,d[x]) to q;
		    send data(0,d[x]) to q;
		    x := x+1;
		    send data(1,d[x]) to q;
		    send data(1,d[x]) to q;
		    x := x+1
end


process q
var 	e: array [integer] of integer
    	y: integer,	       {index of e; init. 0}
    	exp, s: 0..1,       {init. 0}
    	t: integer	       

begin
	rcv data(s,t) from p -->
	    	      if exp = s --> e[y], y, exp := t, y+1, exp +2 1
		      [] exp != s --> {discard data} skip
		      fi
end