cnw

Question

Answer 1

UDP is a message oriented protocol whereas TCP is a byte oriented protocol . Hence TCP transfers a contiguous stream of bytes. TCP assigns a sequence number to each byte transmitted . The receiving TCP uses the sequence numbers to rearrange the segments when they arrive out of order . 

Good read ==>  http://ssfnet.org/Exchange/tcp/tcpTutorialNotes.html

TCP has a sequence number field of 32 bits and hence with each byte , it assigns sequence number (0 to 2³² - 1) to uniquely identify each byte sent and received . So, as the sequence number clock count starts from 0 and goes upto 2³² - 1, then it wraps around and again starts from 0 . Hence,  total time taken by sequence number clock to count from 0 to 2³² -1 and then reversing back to 0 is called wrap around time .

A). TCP utilizes the full bandwidth = 40 gbps and each byte getting one sequence number ,so,

wrap around time = 2³²  B / (40/8) GBps = 0.858993 sec = 859 msec.

B). Now, an added time stamp field increments 1000 times every 859 msec .

So, 1 time in every 859 usec.

Also, 32 bit time stamp will count from (0 to 2³² -1 ).

Hence , time taken by timestamp field to wrap will be ==> 2³² X 859 usec ==>

3.68 X 10¹² usec .

Answer 2

a))

Total Seq in TCP header=32 bit

Total byte=2^32 byte

1 byte take=1/5x10^9 sec

Then 2^32 will take=2^32/5x10^9=0.86 sec