[GTALUG] How do I demonstrate a crappy network?

[Jamon Camisso]

On 19/01/2021 07:19, David Collier-Brown via talk wrote:
> I'm working on an article about advances in Linux networking (eg, Cake), 
> but with a demonstration anyone can do, to convince doubters.
> 
> I therefor need a way to show how crappy someone's network is. I tried 
> Skype "echo" calls and an couple of similar approaches, then tried 
> playing you-tube videos, all while throwing a load on the network.
> 
> But it doesn't /visibly/ fail.
> 
> What is something that I can make fail, either audibly or visually? 
> Showing my grandmother ping statistics isn't going to work (;-))

A couple ideas:

1. Saturate your link using iperf in client mode, connected to a remote 
iperf server with more throughput capacity than your uplink. Then run 
your demonstration application.

2. Mess with MSS/MTU sizes, perhaps in concert with iperf generated load.

3. DDoS yourself with some raw or spoofed packets.

4. Fill up your connection table, either with lots of connections, or by 
lowering the limit.

The problem with all of these is that TCP is designed to deal with 
dropped & timed out packets, and applications that use UDP usually have 
some perceptual encoding algorithm that tolerates missing datagrams up 
to a point.

Let us know how you get on with this project!

Cheers, Jamon