Consider the network in Figure 3 consisting of a 100 Mbps Ethernet, an Ethernet
ID: 3697700 • Letter: C
Question
Consider the network in Figure 3 consisting of a 100 Mbps Ethernet, an Ethernet switch (without cut-through switching functionality), and a 10 Mbps Ethernet. Suppose that A wants to send a large number of 5,000 bit packets to B. (The 5,000 bits Include the data and all Ethernet header, trailer and preamble fields.) Suppose this is the only active session on the network. Assume propagation delays and processing times are negligible, and acknowledgements are instantaneously returned from B to A. Find the round-trip time, d (Recall that the round-trip time is the length of time from when a host begins to transmit a packet until when the host receives an acknowledgment of the packet.) What is the maximum throughput in packets per second from A to B? Suppose A uses a pipelined transmission protocol with a window size of W=1 packet. Find the throughput m packets/sec. Suppose the window size is W=2 packets. Find the throughput in packets/sec.Explanation / Answer
1)Conside ACKNOWLDGEMENT size is 46 Bytes
2)A Packet transmit in 2 ways
A---------> SWITCH---------->B
A -----------> SWITCH is 100Mbps
SWITCH------------->B is 10Mbps
3) To Transmit a Packet following steps will be taken place
5000 bits from A------------> SWITCH
5000bit from SWITCH -------> B
368 bits(Acknowldgement) from B----------> SWITCH
368 bits(Acknowldgement) from SWITCH----------> A
Qusetion a) :- Round Trip Time
100Mbps = 104857600 bits/sec
5000 bits from A------------> SWITCH = 0.048 ms(milli seconds)
5000 bits from SWITCH--------> B = 0.48
368 bits(Acknowldgement) from B----------> SWITCH 0.035
368 bits(Acknowldgement) from SWITCH ----> A 0.0035
Round trip time for 1 packet is 0.5665 ms(milli secs)
Question b:-
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Maximum Through put is
o.5665 *1000 (1 sec = 1000ms) = 566 packets per sec