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TCP-Fast-Open-Experimentation

Course Code: CO300

Assignment

Webpage

https://derikclive.github.io/TCP-Fast-Open-Experimentation/

Overview

TCP Fast Open (TFO) is an experimental update to TCP that enables data to be exchanged safely during TCP's connection handshake. It does so to save one RTT, while avoiding severe security threats. The summary of the TCP Fast Open RFC can he found here.

Why TCP Fast Open when we have persistent HTTP Connections?

HTTP Persistent Connections reuses TCP connections for multiple transactions ad thus saved the overhead involved in the three way handshake. However accoring to the statistics from Chrome, over one third of the HTTP requests (cold requests) make use of new TCP connections. But TFO overcomes this issue by allowing data to be exchanged during the initial TCP handshake itself.

To run this code, set up a Google Cloud Instance with the folowing specs:

Machine Type

  • 1 vCPU with 3.75 GB memory

Boot Disk

  • Ubuntu 14.04 LTS

Check the following under Firewall

  • Allow HTTP Traffic
  • Allow HTTPS Traffic

Click ‘Create’.

Run the following commands after logging in through SSH:

sudo apt-get update
sudo apt-get -y install git

Clone the repository

git clone https://github.com/derikclive/TCP-Fast-Open-Experimentation/

You can check the perfomance of TFO for the following two HTTP request methods:

  1. HTTP GET

To see the results of the GET request using TFO do the following:

  • Run the python file to start:
cd TCP-Fast-Open-Experimentation/HTTP\ GET
sudo python run.py
  • After 15-30 minutes, the results are written into results.txt and the file plots.png will display the compaarison of TFO and Vanilla TCP using graphs.
  1. HTTP POST

To see the results of the POST request using TFO do the following:

  • Upload the file you want to upload to the server into the TCP-Fast-Open-Experimentation folder.
cd TCP-Fast-Open-Experimentation/HTTP\ POST

  • Change the path in the measure_transfer_time function of the tfo.py file to point to the path of the file you uploaded.

  • Run the python file to start:

sudo python run.py
  • After 15-30 minutes, the results are written into results.txt and the file plots.png will display the compaarison of TFO and Vanilla TCP using graphs.

Challenges Faced

  • We faced a lot of issuses when we tried to install mininet on Ubuntu 16.04 (openvswitch-controller), so we had to switch to Ubuntu 14.04 using the Google Cloud Server.
  • We also took a lot of time to understand the code of the CS244'17 TFO project as it lacked documentation in few places.
  • We intially faced of lot of issues while using the POST operation on the SimpleHTTPServer module. We then realised that the SimpleHTTPServer module did not support the POST requests (it only supported the GET requests). So we used the BaseHTTPServer module and wrote separate functions for handling the POST and GET requests and finally we got the module working.
  • We also had some difficulties using the curl command (for POST requests) on mininet. After lot of debugging and changing the IP address of the hosted website we got the curl command to work properly on mininet.

Inferences

  • From our experiments we found that TCP Fast Open was especially useful for website visitors who are a great distance away from the origin server therefore increasing round trip times.
  • We also observed that the page load time (HTTP GET requests) of TFO over Vanilla TCP improved as the size of the webpage increased and as the bandwidth increases.
  • But there was no improvement on using TFO when a HTTP POST request (Uploading a file) was given to the the server.
  • We also observed that our PLTs are significantly larger than the ones in the paper for amazon.com. We believe that this is reasonable given that the paper was published in 2011, and the sites mentioned likely had much slimmer pages.

Enabling TFO in linux kernel

You need to have linux kernel at least 3.7.

You can check via uname -r, it will give the result similar to following.

4.4.0-98-generic

Then follow the following steps to enable Fast TCP Open

Edit /etc/sysctl.conf and add the following line to its end of file net.ipv4.tcp_fastopen = 3

Save the file.

Execute sysctl -p to make it taken into effect.

Make it permanent even after rebooting system by adding the following line into /etc/rc.local

echo 3 > /proc/sys/net/ipv4/tcp_fastopen

To view TCP connections and to view the TFO cookies generated, use

ip tcp_metrics

References

[1] Sivasankar Radhakrishnan, Yuchung Cheng, Jerry Chu, Arvind Jain, and Barath Raghavan. 2011. TCP fast open. In Proceedings of the Seventh COnference on emerging Networking EXperiments and Technologies (CoNEXT '11). ACM, New York, NY, USA, , Article 21 , 12 pages. DOI=http://dx.doi.org/10.1145/2079296.2079317.

[2] https://tools.ietf.org/html/rfc7413.

[3] https://reproducingnetworkresearch.wordpress.com/2016/05/30/cs244-16-tcp-fast-open/.

[4] https://reproducingnetworkresearch.wordpress.com/2017/06/05/cs244-17-tcp-fast-open/.