[PD] thoughts on Pd's networking framework

[Mathieu Bouchard]

On Mon, 24 May 2010, Ivica Ico Bukvic wrote:

> Using either off-the-shelf wifi hardware or an industrial strength wifi 
> router (in our case Cisco), we get unexpected lag spikes on local WLAN 
> with 16 clients at times even exceeding 2 seconds for some of the 
> clients.

Can you automate measurement of the lag time ? Then can you plot the lag 
time in function of the number of clients ? (add clients one at a time...)
I don't know whether this will help, but it can make an unexpected a-ha.

> When using off-the-shelf router we even had clients drop connections to 
> the router in a high-traffic context. By using an industry strength 
> router these took much longer to occur (but have still nonetheless 
> occurred).

What's a high-traffic context here ? is it the 16 connections above, or 
more like 4000 connections ? how much data per connection ? you mean 
high-traffic to your ports, or high traffic for other matters ?

> Without looking closely at Pd's network code one suggested culprit by a 
> CS colleague might be how Pd reuses ports and a possibility of it 
> starving the router. Is this possible?

no idea what that means. can you get a more complete explanation from that 
person ?

> The problem is apparent when sending sporadic TCP packets to all 16 
> machines as well as when using both UDP and TCP connections.

oh, there are 16 machines... but how many [netreceive] are there per 
machine, and how many [netsend] are there per machine ? can this have any 
impact ?

> One last thought is whether there might be something on the router 
> settings that would make this an issue in both cases.

Are those computers next to each other and next to the router ? why didn't 
you use a wired network for them ? you don't have to use wires, but wires 
can be used to troubleshoot the problem, plus, they are more stable and 
predictable than microwaves. But before spending any money on this, I'd 
spend some time with the rest of the possible problems...

  _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard, Montréal, Québec. téléphone: +1.514.383.3801