GSOC2019TCPTestingAndAlignment

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Project Overview

• Project Name: TCP Testing and Alignment
• Student: Apoorva Bhargava
• Mentors: Tom Henderson, Vivek Jain
• Abstract: This project aims at aligning the ns-3 TCP with Linux kernel to have a more realistic implementation of TCP in ns-3 with proper documentation of the differences. The features of TCP which will be aligned are ECN, RACK, SACK, DSACK, and Paced Chirping. To achieve this, ns-3 DCE (Direct Code Execution) will be used. DCE (Direct Code Execution) is a framework that allows the users to run kernel space protocol inside the ns-3 without changing the source code.
• Code: to be added
• About Me: I am a 2nd-year postgraduate student at National Institute of Technology, Karnataka India. I have worked on Implementation of TCP Jersey in ns-3 and Implementation Cautious Adaptive RED in ns-3 during my first year of postgraduation. Currently, I am working on Alignment and Validation of ns-3 TCP with Linux TCP using ns-3 Direct Code Execution (DCE) framework.

Technical Approach

Many features of ns-3 TCP are aligned with RFCs but not with TCP implementation in Linux. The main goal of this project is to have a Linux like TCP implementation in ns-3 and cover main components of TCP Prague i.e ECN, DCTCP, RACK and Paced Chirping. I have already done the alignment of Slow Start and Congestion Avoidance phase of ns-3 New Reno with Linux TCP Reno and validated it in simple dumbbell topology with one sender and one receiver using ns-3 DCE. Results can be found here. Currently, I am working on alignment of PRR recovery algorithm of ns-3 with Linux using ns-3 DCE as it is default recovery algorithm in Linux kernel. Further, I will work on the alignment of ECN followed by DCTCP, as DCTCP uses ECN feature of TCP in its algorithm. Next, I will cover the alignment of RACK which will also cover the alignment of SACK and DSACK as these two are the pre-requisites. Lastly, the alignment of Paced Chirping will be done. Validation of all the aligned features of ns-3 TCP will be done using ns-3 DCE and proper documentation of all the differences will be provided. Also, if time permits I will try to align the ns-3 implementation of TCP Cubic and TCP BBR with Linux kernel.

Milestones and Deliverables

The entire GSoC period is be divided into 2 phases and the deliverables at the end of each phase will be as follows:

Phase 1:

• Align Explicit Congestion Notification (ECN) implementation of ns-3 with Linux
• Align Data Center TCP (DCTCP) implementation of ns-3 with Linux
• Validate the alignment of ECN in dumbbell topology using ns-3 DCE
• Validate the alignment of DCTCP in data center topology using ns3-DCE

Phase 2:

• Align ns-3 implementation of Selective Acknowledgement (SACK) and Duplicate Selective Acknowledgement with Linux
• Align ns-3 implementation of Recent Acknowledgement (RACK) with Linux
• Validate the alignment of SACK, DSACK, and RACK using ns-3 DCE
• Align ns-3 implementation of Paced Chirping with Linux
• Validate the alignment of Paced Chirping using ns-3 DCE

Weekly Plan

Community Bonding Period (6 May - 26 May 2019)

• Contact the mentors and update weekly plan according to their suggestions
• Setting up a git repository for the project
• Get suggestions on the testing scenarios which will be used for the validation
• Work on the alignment of PRR as it the default recovery algorithm in Linux

Week 1 (27 May - 2 June 2019)

• Start understanding the codebase of ECN in ns-3 as well as in Linux
• Document the differences observed in ECN code of ns-3 and Linux

Week 2 (3 June - 9 June 2019 )

• Align the differences found in ECN and validate the implementation in dumbbell topology using DCE

Week 3 (10 June - 16 June 2019)

• Validate Data Center TCP in data center topology using DCE

Week 4 (17 June - 23 June 2019)

• Start understanding the codebase of SACK in ns-3 as well as Linux
• Document the differences observed

Week 5 (24 June - 30 June 2019)

• Align the differences found in SACK and validate the implementation using DCE

Week 6 (1 July - 7 July 2019)

• Study the codebase of DSACK in ns-3 and Linux
• Document the differences observed

Week 7 (8 July - 14 July 2019)

• Align the differences found in DSACK and validate the implementation using DCE

Week 8 (15 July - 21 July 2019)

• Study the codebase of RACK in ns-3 as well as in Linux
• Document the differences.

Week 9 (22 July - 28 July 2019)

• Align the differences found in RACK and validate the implementation using DCE

Week 10 (29 July - 4 August 2019)

• Study the codebase of Paced Chirping in ns-3 as well as Linux
• Document the differences

Week 11 (5 August - 11 August 2019)

• Align the differences found in Paced Chirping and validate the implementation using DCE

Week 12 (13 August - 19 August 2019)

• Submit all the required patches

Weekly Progress

Community Bonding Period

• Communicate with the mentors through call
• Set up my git repository
• Reported a bug by creating a merge request and it got merged into mainline of ns-3