From: guy keren (choo_at_nonexisting.hamakor.org.il)
Date: Tue 25 May 2004 - 17:50:14 IDT
On Tue, 25 May 2004, Amir Hardon wrote:
> I started downloading the floppy image from the mirror that replied to my ping
> the fastest, but the download speed was very low...
this is because 'ping' checks latency, not bandwidth.
> I tried to send bigger pings (of 1000 bytes) and still found no relation
> between the ping reply time and the actuall download speed...
TCP packets get larger then this - a ping of 1400+ bytes would be more
appropriate, however....
> Why is this? is the only way to find the fastest host is to start downloading
> and check the actual download speed? Isaw some windows programs that looks
> for the fastest mirror before downloading (I think one of them is Getright),
> how does they do it?
any router along the way (as well as the original server) can decide to:
1. define different QoS characteristics for different services (e.g. give
ping's ICMP echo/echo-reply a high priority, so no matter how link is
by http traffic, ping will get a fast response).
2. throttle connections - e.g. using 'thttpd' (tiny/trivial/throttling
http daemon) - which can define how much bandwidth each TCP connection
will have.
in a perfect world, pinging would have been enough.
in our internet, only downloading could tell you something, and even
that's not enough - they might favor short downloads over long ones (i.e.
the connection starts fast, but after a given ammount of data was
downloaded, the connection's speed is lowered, in favor of newer and
shorter connections).
-- guy "For world domination - press 1, or dial 0, and please hold, for the creator." -- nob o. dy ================================================================= To unsubscribe, send mail to linux-il-request_at_linux.org.il with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail linux-il-request_at_linux.org.il
This archive was generated by hypermail 2.1.7 : Tue 25 May 2004 - 18:00:18 IDT