LinuxSA Mailing list archives

  From: Matthew Tippett <mtippett@ticons.com.au>
  To  : lloy0076 <lloy0076@senet.com.au>
  Date: Sun, 14 Nov 1999 09:49:21 +1030 (CST)

Re: Differece (http and ftp)

> Can someone tell me the difference between ftp and http downloads? I
> have an ISP who spits dummies after I've downloaded by any means 250mB
> but I can ALWAYS download http but not ftp....there must be a difference
> and they don't report different download speeds. In fact, I'd be
> inclined to say that http was faster....

Firstly, are you going through a proxy?  If you are, then from you to the
proxy it is *ALWAYS* HTTP.  It could be the proxy not handling FTP's
as quickly as HTTP's, or caching in the proxy.  If your ISP uses transparent
proxying it could also be possible problems it that way, FTP is actually 
quite a problem because of embedded IP addresses in the protocol (hence 
the kernel needs a module to munge the data when doing masquerading).
Another possible thing could be that HTTP is given preference over all
other network protocols in their network architecture.

I personally find that typically FTP is more reliable, (since you can drop
to a FTP client that won't drop the file after 99% - which is what NS seems
to want to do all the time :().

HTTP is a lighterweight protocol.  It is a simple transfer designed for
connect, data, close.  

FTP uses two channels a data and a control channel.  If you look at 
netscape downloading an FTP file (that isn't through a proxy, you can
see that it is a two stage process.  You start downloading from ftp.foo.com
and it turns will display in the status bar, "connecting to host 
ftp.foo.com:43234".  FTP has a full control protocol associated with it.

I can't dig out the RFC references, but both protocols are available fully
as RFC's at various places around the internet, you should find very quickly
that FTP is a lot more complex a protocol.

Between the protocols there should be almost no difference in speed, I would
say that *maybe* HTTP would be marginally faster.

Regards,

Matt


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