FreeBSD Traffic Shaping?

Vincent Poy vince at oahu.WURLDLINK.NET
Fri Feb 6 07:21:14 PST 2004

On 6 Feb 2004, Dan Pelleg wrote:

> Vincent Poy <vince at oahu.WURLDLINK.NET> writes:
> > Greetings all:
> >
> > 	I have a ADSL connection where the upstream pipe is smaller than
> > the downstream with it at 1.5Mbps/384kbps now and will be upgrading to
> > 6Mbps/608kbps soon.  The issue I'm having is that whenever I upload, it
> > fills the upstream to full capacity and the downstream would lag as the
> > ACKs can't be send back in time.  I was told that with traffic shaping or
> > fair queue routing would solve this issue but I only have one NIC
> > interface as I am running FreeBSD on a fully loaded notebook with a
> > Pentium 4M-2.6Ghz CPU, 2GB RAM and 60GB 7200RPM HDD with a 10/100 3COM xl0
> > built in NIC.  The problem is that I have 8 static IP's with my ISP so
> > that the LAN IP's, x.x.x.224-.231 netmask are all locally on
> > the LAN so I want those to use the full speed of the connection without
> > traffic shaping.  The NIC also has the 192.168.x.x netmask
> > addresses for the local LAN as well so how do I setup traffic shaping in
> > this scenario so that only traffic that actually uses x.x.x.1 from the
> > x.x.x.224 IP that isn't local LAN traffic actually use traffic shaping or
> > fair queue routing while LAN traffic will just use the full speed.  I
> > already have these options in the KERNEL config.
> >
> > options         IPFIREWALL
> > options         IPDIVERT
> > options         DUMMYNET
> > options         BRIDGE
> >
> > 	Thanks for your help in advance!
> See ipfw(8). You can match rules by interface or address mask, so you don't
> need to touch LAN traffic.

	That's the part I'm confused about.  Since I only have one
interface, I assume I have to do it by address mask but how would one
define it as for example, would not use the traffic shaper but as well
as would?

> Correct, the problem when you upload on an assymetric link has to do with
> acknowledgment packets that downloading apps need to send back to the
> remote server, and they have to wait in the upload queue (which is
> saturated). You need to prioritize those. One way to do this is to filter
> on small iplen. This has been discussed in the mailing lists in the past
> (try the archive of the ipfw@ list). Just remember you can only shape
> outbound packets (ie, leaving your computer). Doesn't matter if they're up
> or down the DSL line, just that they go out (shaping incoming traffic makes
> no sense).

	True.  But when you have the shaping, do you actually set it to
the speed of the line or do you set it to like 5% below the speed of the
line and on the acknowledgement packets, does traffic shaping actually
reserve some space for that to go back or does it just queue it a certain
way?  Thanks.

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