[olug] Traffic prioritization

[Obi-Wan]

Hey all,

I currently have a CentOS 5 (RHEL 5) box running IPtables as my firewall
and PPPoE termination point between my local network and Internet Nebraska.
I run mail & web servers locally, and do a fair bit of off-site copying
over an SSH tunnel.  Since my upstream pipe is pretty slow, I often find
my link saturated by HTTP or SSH-copy traffic, which makes interactive
usage difficult.

Is there a good way, preferably using my existing firewall box, to
prioritize traffic by port or IP without strictly limiting the bandwidth
if nothing else is contending for it?

For example, I want IMAP/SMTP to have top priority, followed by
interactive SSH, followed by incoming HTTP, followed by outgoing
HTTP, followed by SSH-copy (different port).  However, if the SSH-copy
is the only thing happening, I want to allow it to use my entire pipe.

Any suggestions?

-- 
Ben "Obi-Wan" Hollingsworth                             obiwan at jedi.com
   The stuff of earth competes for the allegiance I owe only to the
     Giver of all good things, so if I stand, let me stand on the
       promise that You will pull me through.  -- Rich Mullins