From: Chris Kuethe (ckuetheualberta.ca)
Date: Fri Jan 02 2004 - 11:07:38 CST

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On Fri, 2 Jan 2004, Eric Pogroski wrote:

> Isn't it somewhat true, though? For what the original post was asking for,
> I've never tried to use just altq to limit bandwidth, outside of assigning
> lower priority to diffent types of traffic, which I was taught is not
> actually limiting bandwidth, just a re-prioritization of such (mind, this
> is rhetoric from an RHCE course I took...

right, and what happens when i reprioritize traffic and shove it into a
queue - say a token bucket regulator - that can send up to 10 packets (or
tokens) per second?

10 packet/sec * 1500 bytes/packet * 8 bits/byte / 1024 = 117 Kbit/sec

that's our upper bound for this simple-minded queue. there are a number of
other schemes in place that can allow you to dial in some number of bps and
they'll take care of the rest; whether you're sending big packets (ftp) or
little ones (ping flood).

you might want to have a look at the altq homepage and dig up some of the
papers mentioned on citeseer. it's a great (and educational) way to spend
a weekend...

http://www.csl.sony.co.jp/~kjc/software.html
http://citeseer.nj.nec.com/cs/

> ... so obsd's way of doing things is bound to be different - perhaps it's
> time I looked into some other alternate avenue's of education).

like breaking out the manpage and trying it yourself.

seriously, i'm not trying to be a smartass here. grab some of the example
rules and jiggle one or two of the knobs at a time and see what happens.

        'altq on $ext_if priq bandwidth 100Kb queue { q_pri, q_def }'

change that 100Kb to something an watch your net use. i'm somewhat partial
to the use of wmnet to keep an eye on what's going in and out *right now*.

BTW, a number of the networking papers use the NS network simulator ... we
have it in ports. I've not played with it much yet, but it may save you some
time over setting up a little farm of old boxen to test things with.

CK

--
Chris Kuethe, GCIA CISSP: Secure Systems Specialist - U of A CNS
      office: 157 General Services Bldg. +1.780.492.8135
              chris.kuethe[pyxis.cns.]ualberta.ca

     GDB has a 'break' feature; why doesn't it have 'fix' too?

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