Remember too that if you have multiple types of
flows on your link (FTP, TELNET, HTTP) the key isn’t
so much to utilize your DS3 99% as it is to ensure
that the end user’s expectations aren’t upset. So,
you might use WRED to drop bulky FTP packets instead
of Voice, Video, Telnet, some HTTP, etc…in those cases
where you reach the threshold that you specify. Does an
FTP user really notice if their download starts at
160kbs and gyrates around between 30-150kbs…especially
if they are very large downloads? But a web page taking
12 seconds to load…not good.
It depends on the network owner's priorities. I've had several
customers which considered web pages very low priority. A 70-byte
database transaction longer than 2 seconds was considered a catastrophe.
A web page taking 30 seconds wasn't a priority. I've also had multi-hour
FTP sessions fail due to goofy QOS attempts by networks. A daily FTP
transfer taking more than 24 hours to complete can be a problem.
How come the psychic hotlines at $4.99/minute aren't the highest priority
calls on the public telephone network? Why don't telemarketer calls
interrupt your call to grandmother, if telemarketers are willing to pay
more than your grandmother to speak with you. As the airlines found out
this weekend, QOS can result in inefficient use of resources and longer
lines.