Computer Network: Network Congestion

Question

For a host machine that uses the Token Bucket Algorithm for congestion control, the token bucket has a capacity of 1MB and the maximum output rate is 10MBPS, Tokens arrive at a rate to sustain output at a rate of 5MBPS. The token bucket is currently full and the machine needs send 10 MB of data. The minimum time required to transmit the data is _____ sec.

Solution-

C + PS = MS,  C= Bursty Time, P= Token Arival Rate S= Token generate rate 
1MB + 5S = 10S
S = 1/5 = .2 sec

for .2 sec, data will flow at max rate, hence in .2 sec, .2*10 = 2MB 
Data to be sent = 10MB
Left data = 10-2 = 8MBPS

8MBPS data will be sent = 8/5 = 1.6 seconds

Total time to send 10 MB = 1.6 + 2 = 1.8 Seconds ( correct?)

Comments

Please explain the solution ... i m not getting it

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What i think is:

Relative Rate = 10MBps - 5 MBps

= 5MBps

which means when both actions (token input and token output work) are happening simultaneously then every second 5 MB of data leaving the bucket.

1 sec -------- 5 MB

0.2 sec ----------- 1 MB

Now, it is given in the question that "The token bucket is currently full" so first it needs to transmit the currently held data which is 1 MB as given in the question that bucket capacity is 1 MB.

and for remaining 10MB --------- 2 sec

In total it is 2.2 sec.

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@ Shubhanshu Could you please clear my doubt token bucket will assign token to each packet and now we have a bucket of 1mb how its possible that effective output is 5 mb that you mentioned as relative rate.