Tonight

1
Tonight

• Project 3
• How we graded
• Design Issues.
• Project 5 Discussion/Demonstration
• Finish Network Security
• Steve Mato - XML

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Project 3 - how we graded
Student name your name Student ID your
ID ------------ part1 5 points
------------ Minimum packet time in server log
490 Maximum packet time in server log
550 Average packet time in server log 503 Good,
server Rtt is correct. ------in part1, you get
5 points ------ ------------ part2 5 points
------------ Packets OK in client 78 Packets OK
in server 78 Good, OK count is
correct. ------in part2, you get 5 points
------ ----------- part33 points
------------- Packets Duplicate in client
1 Packets Duplicate in server 1 Good, Duplicate
count is correct. ------in part3, you get 3
points ------
----------- part43points -------------- Packets
Corrupt in client 2 Packets Corrupt in server
2 Good, Corrupt count is correct. -------in
part4, you get 3 points ------ -----------
part53 points -------------- Packets Reorder in
client 1 Packets Reorder in server 1 Good,
Reorder count is correct. -------in part5, you
get 3 points ------ ----------- part6 3
points ------------- Packets Dropped in client
21 Packets Dropped in server 19 Good, Dropped
count is correct. ------in part6, you get 3
points -------
----------- part7 8 points ------------ Minimum
packet time in client 0 Maximum packet time in
client 1820 Average packet time in client
78 Good, client Rtt is correct. ------in part7,
you get 8 points ------- Student name
your name Student ID your
ID ------------- record of score ------------
Part1 5 Part2 5 Part3
3 Part4 3 Part5 3
Part6 3 Part7 8 ----------------------
-------------------- GRADE
30 ------------------ end -----------------
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Project 3 - Design Issues

• Use Threads with shared data structures
• sender
• make a packet, add info to ss, send, sleep
• receiver
• receive a packet, classify, update ss, record
• timer
• scan list of sent packets in ss, process drops

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Project 3 - Design Issues

• What info to share
• current packet (pn)
• list of sent pn time sent
• How to measure RTT
• put current time in packet on send
• subtract packet.time from current time on receive

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Project 3 - Design Issues

• Checksum
• treat message as short of length n
• short sum 0
• for (i 0 ilt n sum bufi)
• append short to buffer and send
• on message receive, compute sum for entire
  message (including checksum) 0

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Project 3 - Design Issues

• Detecting duplicate packets
• use the list of sent but un-acked packets
• If packet is valid, check list
• if packet is NOT in list, then its been
  received already!
• Detecting out of order packets
• maintain SN of last OK packet
• if new packet SN lt last OK SN, then o-o-o

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Project 5

• How I will grade
• test that your source compiles runs on NYU
  Solaris machines!
• If not, project will get minimum score (10/20)
• check your program against HPS Tester
• you get points score of tests (20 is top score)
• A demonstration .