1. Jacobson/Karel algorithm and Original (use ? = .8) for TimeOuts for TCP:

Assume EstRTT = 2, Deviation = 1, ? = 0.1, ? = 1, and ? = 4 . Do this for both Jacobson/Karel and Original algorithms. You must first compute the TOs before the first packet is sent. Then you send three packets and they have SampleRTT values = 4.3, 2.0, 5.0, and explain what would happen. Give the TO after the third packet as well.

You want to show which packets timeout by each algorithm. Do not worry about retransmissions affecting the RTT values.

Jacobson/Karel Algorithm:

Diff = SampleRTT EstRTT

EstRTT = EstRTT + (? x Diff)

Dev = Dev + ?( | Diff | - Dev)

TO = ? x EstRTT + ? x Dev

Before packets are sent

TO = (1 x 2) + (4 x 1) = 6

Compute Timeouts after each packet is sent and ACKs received.

Packet 1

Packet 2

Packet 3

Jacobson/Karel Show if

Packet 1 times out

Packet 2 times out

Packet 3 times out

Original

EstRTT = ? x EstRTT + (1 ?) x SampleRTT

TO = 2 x EstRTT

Before packets are sent

TO = 2 x 2 = 4

Timeouts after packets sent and ACKs received.

Compute Timeouts after packets sent and ACKs received.

Packet 1

Packet 2

Packet 3

Jacobson/Karel Show if

Packet 1 times out

Packet 2 times out

Packet 3 times out

The time outs for each algorithm are:

	Before packets are sent	After Packet 1	After Packet 2	After Packet 3
Jacobson/Karel
Original