Re: FR versus ISDN
Charles Scott (cscott@freeway.net)
Fri, 30 May 1997 09:49:35 -0400 (EDT)
Arnaud:
The latency will of course depend on what you have on the ends of the
circuit. If there's an external ISDN unit at either or both ends then
you add the latency caused by the serial links to the modems.
We feed one POP with 2 ISDN FX lines (4 B channels). The lines have
Bitsurfr's at each end and we're running the serial ports at 230.4K to
PortMaster serial ports at each end. Ping times run a minimum of just
under 70 ms. Obviously, that would be the same regardless of the number
of B channels we had up and running.
The 70 ms time is obviously much more than you would normally get with
FR but the throughput is the important part (to everyone except the
real-time game players).
I'd rather be running FR or a conventional dedicated line to that
location but the numbers didn't work out in this case. Unfortunately the
reliability of those ISDN lines is not as good as what we've seen
elsewhere which may push us to finally put in a "real" circuit.
Chuck
On Thu, 29 May 1997, Arnaud Girsch wrote:
>
> > Other than cost, what are some other advantages?
>
> I experienced a very slow latency over ISDN ...
> An established connection between two sites, 300 miles, PacBell - AT&T - GTE,
> has about 130ms for 40bytes packets ....
> I found that a little bit slow. I didn't have the exact same config with FR,
> but I think this is a little bit faster (someone else can comment ?)
>
> Arnaud.
>
> --
> Arnaud Girsch -+- Marben Products, Inc. / DSET Corporation - San Jose, CA
> agirsch@marben.com -+- http://www.marben.com/ -+- http://www.dset.com/
>