🚀 go-pugleaf

In article <3tdln0$8fe@news1.mcs.net>,
Phil N. Schuman <pschuman@interserv.com> wrote:
>I've seen various comments concerning the speed of ISDN when used 
>with different types of DCE.
>
>However - I think it would be most useful to see a set of real world figures
>for a GIF or ZIP FTP, and/or a WEB page transfer for the following:

Ok :-)

25kbps	>28.8 modem
50kbps	>ISDN TA - single B channel - V.120 rate adaption
55kbps	>ISDN TA - single B channel - async/sync PPP connection
63kbps	>ISDN ethernet router - single B channel
126kbps	>ISDN ethernet router - both B channels

These are for compressed data.  Uncompressed data gives much higher rates
for the last two options if you're using a compatible device.  For example,
an FTP of a postscript document via a 2B ISDN connection on a P50 here gives
nearly 260kbps in real throughput.  Now THAT is fast!

>of course - the timings would have to be on the same file, and tried a couple of times
>to ensure some consistent stats.  
>But, I would like to see the bits/sec and the overall
>transfer time for the file transfer.  

See above.

>any other testing conditions, discussion, or stats would be greatly appreciated.
>
>Phil - 

There are two issues to throughput:

Latency
Raw bit rate

The first affects interactive connections severely.  TAs in general are
unable to get below 100ms on a "ping" response.  This is due to the
packetization that must be done with either V.120 or Sync/Async conversion
to get the data from one end to the other.  

This is, by the way, pretty close to what a V.34 modems can give you in
terms of interactive responsiveness.  Not bad, but not great either.

Raw bit rate varies less.  TAs generally will only run an effective 57.6kbps
DCE rate, although we have seen some which will clock at 115.2kbps.  The
problem then becomes having a serial port which will accept data at that
speed without dropping it.

Very few PCs can handle this without an add-on card like the Hayes ESP
board.

Ping times look like this:

TA V.120	>> TA V.120		~ 150ms
TA Sync/Async	>> Ascend MAX		~ 100ms
Ethernet 1B	>> Ascend MAX		~ 30ms (!)
Ethernet 2B 	>> Ascend Max		~ 23ms (!)

Note that the 1B return speeds are faster than a dedicated 56kbps circuit,
which runs about 35 - 40 ms.  As such it is quite impressive.

2B connections are 128kbps in real throughput.

All these numbers were taken from my testing at MCSNet between my home
environment and the office.  The TA figures are a couple of months old --
the others are current (within the last two to three weeks).

--
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