[oclug] POTS -> SIP providers in Canada?

[Brad Barnett]

On Mon, 25 Apr 2005 20:03:31 -0400
Adrian Irving-Beer <wisq-oclug at wisq.net> wrote:

> On Mon, Apr 25, 2005 at 07:46:09PM -0400, Brad Barnett wrote:
> 
> > Unless you are dropping upstream bandwidth to about 65% or 70% of
> > full speed, you aren't assured that the modem won't queue the
> > traffic itself.. and cause delays in traffic you don't want delayed.
> >
> > If he's had no complaints, it has been luck... or people not
> > commenting on the quality.
> 
> The link in question was calibrated in particular to prevent any
> severe SSH delays during major downloads or even major uploads.  We do
> a lot of those, and it frustrated me to no end -- until I set up
> proper rules. Now VoIP benefits from those.
> 
> I also used TCP MSS tricks to lower the TCP packet size of our more
> common major data transfers, ensuring that the queuing disciplines
> could more effectively perform their job.
> 
> It does involve some limiting, yes.  But with the steps above, the
> limiting doesn't need to be particularly low.  I found it was less
> about percentage and more about a fixed margin; hence, the percentage
> loss decreases with higher speeds.
> 
> Sorry I don't have exact numbers -- I did this all ages ago.  I know
> what it's set to, but I just don't know what percentage of the
> effective max that is.

Well, I'm sure you're at least below 85%.  I'd be surprised otherwise.

> 
> > If he's had no complaints, it has been luck... or people not
> > commenting on the quality.
> 
> Believe me -- if he had a network issue, I'd hear about it. ;)
> 
> And as for luck, he uses it most of the day, talking to clients.  Bad
> luck has had many chances to manifest.

I suppose.. but how often does he upload large files?  Perhaps he isn't
using upstream all that much?

> 
> > > Also, according to one report I heard, a Linksys VoIP box reduced
> > > someone's bandwidth from 400 kb/s to 200 kb/s *all* the time, even
> > > with no call in progress.
> >
> > Perhaps a VOIP QOS router, and not a router with SIP built in.
> 
> I'm not familiar with what you're referring to here -- I know what
> each acronym means, just not how they all fit together. ;)

There are routers that advertise "voip qos".  In other words, they just
give SIP packets, when seen, priority.  

> 
> In any case, if it clarifies things:  This was one of the Linksys
> boxes I mentioned.  They have a WAN port (like a normal router),
> some LAN ports (ditto), but a phone port that hooks up to a normal
> land phone.
> 

Ok, so this is a real SIP voip router.  

I haven't seen those figure with the units I've deployed.  In fact,
I've seen very little slowdown.  It's quite possible that some of the
earlier models were flawed, but newer models, or new firmwares, took care
of a bug.


> They're meant to simultaneously be your VoIP and your home router, but
> apparently (according to the forums) some people put them behind a
> different router due to the bandwidth limiting issue.