CS6250

Project code for CS6250 (Computer Networking) at Georgia Tech for fall 2014, lectures freely available through Udacity. Work done using Mininet to simulate network environments.

Nam Pho ([email protected])
Forked from https://github.com/OMS6250/gt-cs6250 on 9/4/14

##Table of Contents

• Notes
• assignment-2 Mininet Topology
• assignment-3 Parking Lot
• assignment-4 Learning Switch
• assignment-5 Buffer Bloat
• assignment-6 TCP Fast Open
• assignment-7 TBA
• assignment-8 TBA
• assignment-9 TBA

####Notes 1. Clone the original OMS6250 repo and fork it.

$ git clone https://github.com/OMS6250/gt-cs6250.git

2. Adjust the repo to point to your fork and then upstream as the original.

$ git remote set-url origin [email protected]:nampho2/CS6250.git
$ git remote add upstream https://github.com/OMS6250/gt-cs6250.git

3. Keep fork in sync with original from Github docs.

$ git fetch upstream
$ git checkout master
$ git merge upstream/master

4. Adjust PYTHONPATH environment variable to include helpful cross-assignment imports.

export PYTHONPATH=`pwd`/lib/:$PYTHONPATH

or

export PYTHONPATH=/home/mininet/gt-cs6250/lib/:$PYTHONPATH

####assignment-2: Mininet Topology

• Run topology.sh and review output.
• Modify mntopo.py to insert an additional switch between the hosts. Helpful to review Mininet documentation on this.
• Rerun topology.sh, output should be similar.
• Test latency by running the ping wrapper, ping.py. Should get ~6ms.
• Increase the latency delay from 1ms to 10ms in mntopo.py.
• Re-test latency. Should get ~60ms.
• Increase the bandwidth from 10Mbps to 50Mbps in mntopo.py.
• Re-run topology.sh and review output.

####assignment-3: Parking Lot

• Complete the __init__ function of the ParkingLotTopo class to generalize this for any number of hosts, n > 0. The resulting topology is as shown in the figure above.
• Complete the run_parkinglot_expt function to generate TCP flows using iperf.
• Final result is running sudo ./parkinglot-sweep.sh to test various parameters of n = 1, 2, 3, 4, 5.
• Run my additional submit.sh script to collect the output of parkinglot-sweep.sh wrapper per submission specifications. Submit all bwm.txt files.
• Complete additional quiz questions in quiz.txt.

####assignment-4: Learning Switch

• Code learn_route() function in learning-switch.py code to generate ARP tables.
• Run topology with commands:

# symbolically link topology to pyretic
$ ln -s ~/CS6250/assignment-4/learning-switch.py ~/pyretic/pyretic/modules/

# run pyretic first
$ cd ~/pyretic/
$ python pyretic.py -m p0 pyretic.modules.learning-switch

# run mininet in separate terminal
$ cd ~/CS6250/assignment-4/
$ sudo python learning-switch-topo.py

# pingall hosts
mininet> pingall

• Answer some quiz questions in hw4.txt.
• Note: use arping to send single ARP packets and watch the learning switch in action to answer quiz.

# install arping in Ubuntu
$ sudo apt-get install arping

# 0. h2 ping (ICMP) h6
mininet> h2 ping h6

# 3. h2 ARP request to h6
mininet> h2 arping -B -c 1 h6

# 4. h6 ARP reply to h2
mininet> h6 arping -b -c 1 -t 00:00:00:00:00:02 h2

# 5. h6 ARP request to h3
mininet> h6 arping -B -c 1 h3

# 6. h3 ARP reply to h6
mininet> h3 arping -b -c 1 -t 00:00:00:00:00:06 h6

####assignment-5: Buffer Bloat

Simulate buffer bloat as seen on typical home ISP connection as seen in the figure below:

The corresponding abstract Mininet topology is represented below:

1. Run select Mininet topology with various buffers and sizes.

# 100 packet router buffer
$ sudo ./run.sh

# smaller 20 packet router buffer
$ sudo ./run-minq.sh

# 2 queue router buffer
$ sudo ./run-diff.sh

2. Run monitoring script if desired, cwnd data saved to <title of run>_tcpprobe.txt file.

$ ./monitor.sh <title of run>

3. Saturate the router bandwidth using iperf script from h1 to h2, watch the packet flow for ~70s for equilibrium and then request data under resource contention and saturated bandwidth using wget.

# run iperf script
mininet> h1 ./iperf.sh

# watch packets, wait ~70s
mininet> h2 tail -f ./iperf-recv.txt

# get data under saturated bandwidth using wget
mininet> h2 wget http://10.0.0.1

4. Visualize how router handles resource contention, go to http://<IP>:8000.

$ sudo ./plot_figures.sh <title of run>

####assignment-6: TCP Fast Open

1. Read the original TCP Fast Open (TFO) paper [PDF] to answer quiz questions. Additional useful slides here.

2. Run the simulation and record as observations.txt file, basically should show that there are web performance enhancements under TFO vs not TFO. Experiment inspired from other assignment.

# install pre-req packages
$ sudo apt-get update 
$ sudo apt-get install vnc4server 
$ sudo apt-get install libnss3-dev 
$ sudo easy_install termcolor

# run simulation
$ vnc4server
$ sudo ./run.sh

####assignment-7: TBA

• Work next week.

####assignment-8: TBA

• Work next week.

####assignment-9: TBA

• Work next week.