LARTC - Feb 2002 - Optimize online gaming at expense of web access

I''ve read the advanced routing FAQ (I suppose that''s a given,
or I
wouldn''t have found my way to this mailing list!), and I''m
assimilating
the information therein... but I''m still unsure of how to best optimize
my system.  Basically, I have a LAN at home that goes through a RH 7.1 
system which serves as a NAT gateway (I use iptables) to the internet 
through an IDSL connection.  Since it''s IDSL, it''s not all
that fast.
Problems arise when my wife is playing an online game (Ultima Online) on 
one computer, while I am browsing large web pages or downloading files 
via the Web or while outsiders access my web page (I run apache on the 
RH system).  So, I''d like to give http a lower priority than other 
system activity.

My basic question is, what''s the best way of doing this?

One example in the HOWTO seems close, but I''m not confident that I 
understand it well enough to adapt it:  section 15.4, "Prioritizing 
interactive traffic".  It recommends using the standard pfifo_fast 
scheduler; if I understand correctly the idea is to set the TOS bits to 
have telnet and ftp control connections go into band 1, while ftp data 
goes into band 2.  This raised a bunch of other questions for me:

Looking at the table in 9.2, it seems that the TOS bits will only send 
packets into bands 1 and 2.  What goes into band 0?  Are there other 
differences between the four TOS settings?  The names certainly suggest 
so.  Are they relevant to the task at hand? What if none of the bits are 
set -- what happens then?  And, in the table, what is TC_PRIO?  Where is 
it used?  I get the feeling that that''s a *very* basic question, but I 
haven''t figured it out.

Anyway, using this approach, I assume that I can toss packets into band 
2 instead of 1 by using:

# iptables -A PREROUTING -t mangle -p tcp --sport telnet \
   -j TOS --set-tos Minimize-Throughput
# iptables -A PREROUTING -t mangle -p tcp --sport ftp \
   -j TOS --set-tos Minimize-Throughput
# iptables -A PREROUTING -t mangle -p tcp --sport ftp-data \
   -j TOS --set-tos Maximize-Throughput

Hopefully the packets sent back and forth by Ultima Online will be in 
band 0 or 1, and this will solve my problem.  Is that right?

Thanks!

Bruce

>  Basically, I have a LAN at home that goes through a RH 7.1
> system which serves as a NAT gateway (I use iptables) to the internet
> through an IDSL connection.  Since it''s IDSL, it''s not
all that fast.
> Problems arise when my wife is playing an online game (Ultima Online)
I have the same set up for my adsl connection. I think the problem you
describe is the bane of all us home network users. I haven got a perfect set
up but I recomend looking at this attachment, which is from another post to
this list a while back.

http://www.ds9a.nl/2.4Routing/HOWTO//cvs/2.4routing/output/2.4routing-15.htm
l#ss15.8

This works quite well, but since you know exactly what the problem is (UO
requires a set amount of bandwidth to keep a good ping) I suggest using a
packet sniffer to find out what ports UO uses and make a seperate bandwith
class just for that port. Forget about the TOS bits from what ive seen they
dont work reliably.

I also think that this setup puts HTTP traffic into the fast class which is
good for when your browsing webpages while somone downloads a big file, but
it does mean that if you look at a particualy large page, (big lists
generated by ASP or somthing) it can hog the bandwidth for a couple of
seconds