[181412] in North American Network Operators' Group
Re: Residential VSAT experiences?
daemon@ATHENA.MIT.EDU (William Herrin)
Tue Jun 23 10:25:31 2015
X-Original-To: nanog@nanog.org
X-Really-To: <nanog@nanog.org>
In-Reply-To: <CAJB2g-EHFpOm39FscA-ry=29kB6WY+8L7X3AWMSq1gu_bKDJww@mail.gmail.com>
From: William Herrin <bill@herrin.us>
Date: Tue, 23 Jun 2015 10:24:58 -0400
To: Rafael Possamai <rafael@gav.ufsc.br>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Tue, Jun 23, 2015 at 9:37 AM, Rafael Possamai <rafael@gav.ufsc.br> wrote:
> Reading about SIP made it seem like latency alone is not an issue, aside
> from delays which impact verbal communication as previously mentioned. What
> is going to be much worse is jitter and packet loss. You can eventually get
> used to a significant delay, but dropped calls and chopped sound renders
> the service useless.
With modern software implementing a responsive jitter buffer, jitter
shouldn't be much of a problem. Practical effect would be a longer
delay as the receiver buffers enough packets to deal with the measured
variance in receipt times. Perhaps a few chops early in the
conversation as the software grows the buffer.
Not all SIP implementations are equal. Try yours in a high-jitter
environment and see what happens.
High packet loss is deadly. That'll depend on the satellite vendor's
network implementation, the weather, etc. But then high packet loss is
deadly to essentially all IP networking activity.
In situations where a high bit error rate (BER) is endemic, the
layer-2 vendor is expected to redress that with forward error
correction (FEC) and retransmission that trades jitter for loss. I
have no idea which satellite vendors are better or worse about this.
Regards,
Bill Herrin
--
William Herrin ................ herrin@dirtside.com bill@herrin.us
Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>
