HW 1 Hints

Taken from Tiberiu Vasile Stef-Praun

The complete manual of TDR.

Here's the example of how to use gnuplot:

Suppose you have the data from the ping experiment gathered in the file data.file
which looks like this (can include comments):

---- data.file ----
#packetsize     min     avg     max
1024            3.2     3.5     4.1
2048            3.5     3.8     4.0
4096            3.8     3.9     4.2
8192            4.1     4.3     4.6
---- end data.file ----


The following script can be used with gnuplot to generate a nice graph for you:

---- test.gp -----
# save to ps file
set terminal postscript eps enhanced
set output "output.eps"
set data style lines

set xlabel "Packet Size"
set ylabel "Avg/Min/Max"
set title "Joe's Graphs"

plot    "data.file" using 1:2 title "Max",\
        "data.file" using 1:3 title "Avg",\
        "data.file" using 1:4 title "Max"

---- end test.gp -----

When using the script, make sure the data file is in the same directory, then:

% gnuplot test.gp

Example output:

You might need a utility to transform the ps file into gif.
You can use this one, provided by the professor ps2gif

Update

The syntax of ping provided at the material is not working with SSLAB machines. The syntax of ping for Linux machines is
```
ping -s (packet size in bytes) -c (# of probings) ip-address
```
(Do the following steps only if you notice ping packets bigger than 2K being blocked.)
You might have noticed that some of the hosts blocks ping packets bigger than 2K. To learn more why that happens, you'll need to additionaly do as follows:
After using traceroute to determine the path to the host, perform
```
ping -s 4096 -c 20 ip-address
```
where IP address is the address of each router (to see whether that specific router blocks the 4K ping or not). Determine this way the router at which ping hangs. Discuss why ping may hang at that IP device.
Perform ping with payload size 2048 bytes for the destinations
```
csa.bu.edu
route-server.east.attcanada.com
route-server.west.attcanada.com
noc.kr.apan.net

(Some of the destinations might not work for reasons. Please record your observation and discuss the result as it is.)  
```
For the max/avg/min values obtained from the four measurement sets, plot a graph where the x-axis denotes the destination IP node (csa.bu.edu, ..., noc.kr.apan.net) and the y-axis plots non-interpolated max/avg/min lines (here it makes no sense to connect the dots across different IP nodes).
The new datafile might look like this :
```
#router					min     avg     max
csa.bu.edu                              3.2     3.5     4.1
route-server.east.attcanada.com         3.5     3.8     4.0
route-server.west.attcanada.com         3.8     3.9     4.2
noc.kr.apan.net                         4.1     4.3     4.6
```
The new gnuplot script will look like this:
```
set xlabel "Router"
set ylabel "Avg/Min/Max"
set title "Joe's Graphs"

plot    "data.file" using 2 title "Max",\
        "data.file" using 3 title "Avg",\
        "data.file" using 4 title "Max"
```
To put the router names on the x-axis use the following:
set xtics ("Router 1", 1, "Router 2", 2, "Router 3", 3)