[LARTC] Re: Shaping incoming traffic on the other interface

[Jason Boxman]

On Thursday 10 June 2004 16:07, Greg Stark wrote:
<snip>
> I'm using sfq as well. But I'm wondering if I wouldn't be better off with
> pfifo with a short queue. One of the entries in the HTB faq suggests using
> sfq can make it hard to limit bandwidth precisely because it requires
> enough memory that tcp_wmem kicks in. Or is that only for locally generated
> traffic?

I tried sticking a limit 10 pfifo on my PRIO n:1 to no avail.  ICMP which I 
add to that class wasn't any better off.  The only sure thing I found was to 
continually reduce my rate.  I find for best performance I'm stuck with 62.5% 
of my 256Kbps upstream.  (We really need some kind of realtime PPPoATM 
scheduler.)  I can run at 75%, but the lag is noticeable when browsing the 
Web, for example.

As for SFQ, you can use ESFQ which lets you specify the actual queue limit I 
believe, or you can recompile SFQ and redefine[1] the queue length in the 
source code.

[1] http://www.docum.org/stef.coene/qos/faq/cache/21.html

<snip>
> I'm still unsure whether I want to be using iptables to mark packets or
> stick with the tc filters I inherited from wshaper.

I'd suggest going with IPTables/Netfilter.  You can't really go wrong.  If 
you're running a firewall with IPTables already, then you're good to go.  
Plus, you cannot deal with most p2p traffic using straight `tc` filters.  As 
always, I suggest IPP2P and L7-Filter for 2.4 and 2.6 respectively.  L7 seems 
to catch 99 - 100% of my 'edonkey' traffic.

> Marking packets in iptables has the advantage that it knows which packets
> were natted and what the host on the far side of the NAT is. It also has
> some more flexible methods for matching.
>
> One thing I'm wondering, is it possible in iptables to mark all packets
> after some amount of traffic? Like, for example I want port 80 traffic to
> be higher priority than ftp-data and bittorrent, but only for regular
> browsing. If I download something over, say, 200k I want to to get
> downgraded to the same group as ftp-data and bittorrent. Also, bittorrent
> has a habit of occasionally using random ports and doesn't set TOS. So if
> iptables knew that that flow had already transfered more than some
> threshold of data it could downgrade it.

Yes, you can do that.  I have been meaning to do it for my HTTP traffic but I 
keep forgetting.  You might try something like this[2].  Or maybe this[3].

[2] http://www.docum.org/stef.coene/qos/faq/cache/49.html
[3] http://www.netfilter.org/patch-o-matic/pom-extra.html#pom-extra-connbytes

> Actually another possibility is any flow open for more than, say, 30s could
> be downgraded.

I just read a paper somewhere that mentioned research into that approach.  
Wish I could remember where I found it now.  It was suggested that giving 
short flows a higher priority over longer lived flows would result in better 
performance for both.

> I don't think the qdiscs handle things at this granularity, but iptables
> sure does. I don't recall seeing any of these features but it doesn't seem
> like it would be much of a stretch for it.

You might check out some of the other patch-o-matic extensions at the above 
URL.