downloads start fast, then slow down

Hi,

My system has been running fine for a while, but now when I download a
large file through my web browser it starts off fast (>300 kB/s), but
then suddenly the speed drops down to 5 or 6 kB/s. I've found that if
I use an ftp client like ncftp, then this doesn't happen. Any ideas?

-Jay

System:
Intel P4 3.2GHz
FC2 linux
2.0GB RAM

> My system has been running fine for a while, but now when I download a
> large file through my web browser it starts off fast (>300 kB/s), but
> then suddenly the speed drops down to 5 or 6 kB/s. I've found that if
> I use an ftp client like ncftp, then this doesn't happen. Any ideas?

usually this is because the browser initiates the request, then starts
drawing the download dialog etc... While it's drawing all this the file is
already coming in, so at first it appears when the dialog catches up with
the download that the first part was coming pretty fast. In reality it's
just catching up with the amount of the file that has already been
downloaded. Your ftp client doesn't have to do any special dialogs or
anything so it doesn't exhibit this "feature".

..... and if u r behind a proxy (i.e. at work) it could have a "delay pools"
configuration.

Pedro


/dev/null el día Martes, 16 de Noviembre de 2004 22:30 escribio:

> usually this is because the browser initiates the request, then starts
> drawing the download dialog etc... While it's drawing all this the file
> is already coming in, so at first it appears when the dialog catches up
> with
> the download that the first part was coming pretty fast. In reality it's
> just catching up with the amount of the file that has already been
> downloaded. Your ftp client doesn't have to do any special dialogs or
> anything so it doesn't exhibit this "feature".

--
GNU/Linux Debian Sarge 2.6.6
KDE 3.2.3 - Knode 0.7.7

"/dev/null" <(E-Mail Removed)> wrote in message news:<sjumd.94936$HA.64884@attbi_s01>...
> > My system has been running fine for a while, but now when I download a
> > large file through my web browser it starts off fast (>300 kB/s), but
> > then suddenly the speed drops down to 5 or 6 kB/s. I've found that if
> > I use an ftp client like ncftp, then this doesn't happen. Any ideas?
>
> usually this is because the browser initiates the request, then starts
> drawing the download dialog etc... While it's drawing all this the file is
> already coming in, so at first it appears when the dialog catches up with
> the download that the first part was coming pretty fast. In reality it's
> just catching up with the amount of the file that has already been
> downloaded. Your ftp client doesn't have to do any special dialogs or
> anything so it doesn't exhibit this "feature".

I don't think that this is the problem because when I use my FTP
client, I get download speeds of >300 kB/s. Also, I used to (last
week) get these speeds using my browser as well (for the entire
download). Any other ideas?

> I don't think that this is the problem because when I use my FTP
> client, I get download speeds of >300 kB/s. Also, I used to (last
> week) get these speeds using my browser as well (for the entire
> download). Any other ideas?

There are a lot of things that can affect tcp speeds from one week to the
next. With tcp it dynamically slows transmissions down according to the
"apparent" speed across the entire connection. IIRC (and it's been a while,
someone feel free to correct me) there are basically two ways:

1. A router along the way hits a bottleneck (it has more data to send
across a link than that link can handle at that moment), it sends back icmp
packets to the sources of the data going over that link saying "slow down".
Usually those sources will then slow the rate down and will not speed back
up for the existing connections.

2. The transmitting end waits for tcp confirmation packets that say "the
remote end got packet X". After so many packets have been sent without a
confirmation it can stop transmission awaiting those confirmation packets
(which will suddenly look like a huge drop in speed) or it can begin to
retransmit some of the "stale" packets, which again appears to be a drop in
speed because the other end probably already has those packets.

Since you are noticing that your ftp doesn't notice this but your browser
does I'd say it's the responsiveness of the browser to the transmission. If
it doesn't respond fast enough in the beginning the transmitting end decides
to slow down and doesn't speed back up.