Re: TCP behavior across WiFi pointers ?

[Mikael Abrahamsson <[e-mail]>]

On Wed, 8 Nov 2017, Toerless Eckert wrote:

> I am primarily thinking that there could be a higher demand for
> TCP (end-to-end) retransmissions when using WiFi because the L2/WiFi
> local retransmissions are insufficient. And if so, what the characteristics

I don't know of any work you're asking for, but from my own experience 
radio networks (wifi + cellular) has the following 
(general) characteristics:

They deliver packets in-order per host.

The try very very hard to deliver all packets (true for unicast only on 
wifi), using L1/L2 retransmits.

Because of this, they sometimes "stall" shorter or longer times, so you 
might get latency spikes of hundreds of milliseconds that are gone in the 
next second. My personal record is 180 SECONDS of RTT on a 2G network.

These latency spikes might cause TCP to believe there was packet loss and 
cause retransmits, where there instead "only" was packet delay.

Radio networks have airtime schedulers, so a single packet and a train of 
packets might have very different network experience. Some network 
types send multiple packets in a single transmit opportunity, and these 
transmit opportunities might be tens of milliseconds apart.

-- 
Mikael Abrahamsson    email: [e-mail]