Subject: [tcpPrague] Suggestions for implementation of pacing in ns-3

From: Deepak K <[email-masked]>
Date: Tue, 19 May 2020 16:30:27 +0530

Hi all,

Over the next few months, I will be working (officially through the 
GSoC program) on improving the current model of TCP Prague in ns-3. An 
implementation in ns-3 has already been provided by Joakim here [1].

After a brief discussion with my mentors, we decided that I should 
begin my work by looking into pacing. Our ultimate goal is to make 
experimenting with TCP Prague easier for everyone, by using 
simulation-based frameworks like ns-3. I also plan on testing and 
aligning our eventual implementation against that of Linux.

[1] currently provides paced chirping for slow start. We were hoping 
for suggestions on how to further incorporate other aspects of pacing 
in our implementation (any particular scenario we should consider, or 
any changes compared to what Linux has implemented, so on).

Thanks
- Deepak

[1] https://gitlab.com/JoakimMisund/l4s-evaluation/-/tree/tcp-prague

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From: Bob Briscoe <[email-masked]>
Date: Tue, 19 May 2020 21:24:04 +0100

Hi, Deepak,

Pacing is by definition about delay variation, and lack thereof. So 
working on pacing in a simulation environment will allow you to gain 
insights into how all the ACKs and packet arrival timings are driving 
each other, without the distraction of timing noise.

The stage where you validate against Linux will introduce some of the 
timing noise that will have to be contended with in real systems. That 
will mean that a true A-B 'validation' will not actually be possible. 
However, at least the diff between the two will give far more insight 
than either just working in a simulator, or just working on Linux.

So this sounds like a good plan. But I would encourage you to take a 
step back part-way through the project (e.g. 20-30% through), and if you 
are still in the simulation stage, trim your project's ambitions so that 
you get time to repeat what you've done in ns3 in Linux.

I mean, it will be far better to do one thing well in both ns3 and 
Linux, than 5 things in ns3 and none in Linux, or 5 things in Linux and 
none in ns3.

HTH

Bob

On 19/05/2020 12:00, Deepak K wrote:
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Bob Briscoe                               http://bobbriscoe.net/