[69148] in North American Network Operators' Group
Re: Overflow circuit
daemon@ATHENA.MIT.EDU (Alexei Roudnev)
Sun Mar 28 02:20:37 2004
From: "Alexei Roudnev" <alex@relcom.net>
To: "Rafi Sadowsky" <rafi-nanog@meron.openu.ac.il>
Cc: "Steven M. Bellovin" <smb@research.att.com>,
"Michel Py" <michel@arneill-py.sacramento.ca.us>, <nanog@merit.edu>
Date: Sat, 27 Mar 2004 23:20:30 -0800
Errors-To: owner-nanog-outgoing@merit.edu
500 RTT, + 150 jitter buffer, + something else... it will be 700 - 800 msec,
more likely. When we worked with a few sattelliite lines (5 years ago), I
never saw ping rtt less than 800 msec. Of course, it does not mean that you
can not see RTT = 500 msec (but I never saw it).
But I was talking aboutt other thing - ~1second delay != bad quality, it is
just a delay, which means that, if you have good echo cancellers (which is
interesting question) and follow talking discipline, you can talk without
any problems. It explains, why satellite links + VoIP can be a good
combination (moreover; after satellite delay, which is 500 - 600 msec, VoIP
additional delay ,which is 50 - 150 msec, does not change overall delay so
much, as in case of VoIP over bad link _vs_ traditional telephony (200 msec
vs 20 msec = 10 times; 800 msec vs. 600 msec = 30%).
>
> ## On 2004-03-27 19:30 -0800 Alexei Roudnev typed:
>
> AR>
> AR> It means, that satellite (with it's 1 second delay and unavoidable
echo)
>
> Geosynchronous satellite IP link RTT can be just over 500 mill-sec
> (real life experience) IMHO thats a rather significant difference
>
> --
>
> Rafi
>
>
