[ILUG] 56K modem throughput

[Dave Airlie]

Key word in that was upload, 56k is download speed only AFAIK, it uses
33.6 k max in the other direction, I'm sure someone here will give the
full explains (something to do with how 56k is implemented with digital
exchange and stuff... ), one reason why ISDN is still better than 56k
modems..

Regards,
	Dave.


On Mon, 24 Apr 2000, Niall wrote:

> I recently upgraded from my old klunker 28.8K modem to a USR 56K external
> message modem. I get connect speeds reported by the modem of 44000 - 49000
> connecting to Surf No Limits. However, I get what I regard as very poor
> transfer rates with ftp or scp - I uploaded a number of largish (~4M files)
> last night to a web server in Esat's farm (so there should be no big
> interconnect delays) and the max. transfer rate I got was < 3K a second,
> going down to 2.2K. I asked Esat's helpless^H^H^H^H desk and the response
> was that about 2.5K/second was about what I'll get on a dialup connection
> with a 56K modem. I know about ppp/modem overheads such as framing bits, TP
> headers etc. - they shouldn't account for that loss of throughput. When I
> was using the 28.8K modem I was getting 2.3-2.4K/sec. and when I had a 33K
> modem (it died, hence the fallback to the 28.8K until I got a new 56K) I was
> getting AFAIR up to 3.1K/sec. So what's happening here ? I haven't tried to
> tune ppp WRT MTU sizes etc. but it should be better than that out of the
> box, I would have thought. What are other Surf No Limits users getting ? Am
> I expecting too much ? BTW when you look at transfer rates, ignore the crap
> that Netscape tells you - the only figure you can reasonably quote is
> throughput reported from scp or ncftp or such.
> 
> 
> 
> Regards,
> 
> 
> Niall
> 
> 

-- 
------------ David Airlie, David.Airlie at ul.ie,airlied at skynet --------
Telecommunications Research Centre, ECE Dept, University of Limerick \
http://www.csn.ul.ie/~airlied	-- Telecommunications Researcher      \
--- TEL: +353-61-202695 -----------------------------------------------