computer networks

Question

Tanenbaum connection establishment 

Answer 1

Part 1)

The 15 bit wide clock counter can produce 2¹⁵ sequence numbers, producing 1 every 100 milliseconds. (1 msec = 10^-3 sec)

$\Rightarrow$ 1 sequence number is produced in 100 x 10^-3 sec,

$\Rightarrow$ 2¹⁵ sequence numbers can be produced in 2¹⁵ x 100 x 10^-3 seconds = 3276.8 sec $\Rightarrow$ 54.61 minutes.

As the sequence numbers will start repeating after the expiry of lifetime (which is given as 60 sec, we dont have any issue)

Part 2)

240 sequence numbers in 60 sec,

$\Rightarrow$ 1 sequence number in $\Rightarrow \frac{60}{240}$ sec

$\Rightarrow$ 2¹⁵ sequence numbers in $\Rightarrow \frac{60}{240} \times 2^{15}$ = 8192 sec $\Rightarrow$ 136.53 minutes

Answer 2

i think this should be the answer

15 bit counter can count 2^15 sequence numbers . so total sequence number will be 2^15. total time to blow up all sequence number =100msec*2^15

=3276.800 seconds (worst case) we have to reset the counter. well as life time of packet is far less than the time to reset counter no issue will occur .

2-

if we use 240 sequence number per minute then.

total time to eat up all sequence number will be

2^15/240=136.5 minutes =137 minutes