Load Balancing Outgoing, its possible ?

G Bryant gbryant at roamingsolutions.net
Mon Oct 31 13:07:21 PST 2005

   Rob Viau wrote:

On Fri, 2005-10-28 at 17:19 +0200, G Bryant wrote:

Daniel Dias Gonçalves wrote:


It is possible to make this balancing with the PF ? Exists some
software that I make this ? Zebra can help me?
This type of balancing gives to problems with the navigation of the
user of NAT or IP valid ?
If it is possible, wanted to see examples with rules.


It would be much better to do per flow load balancing then per packet.
With per packet your TCP flows will arrive out of order which is a bad
situation since it will lead to a large number of retransmissions and
zero-window acknowledgments.

The only tunable to help correct that is to allow selective

You are going to get much higher utilization on your load balanced lines
by using per flow with multiple TCP connections.

Anybody know how to implement per flow load balancing in FreeBSD?  Are
multiple default routes supported?

It would be beautiful if you could put multiple routes with the same
metric into the kernel and then the kernel would enable per flow load
balancing of the routes...

-Corey Smith
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I believe pf is per-flow.  If it was not, then not only would your packets
arrive out-of-order, but also with different source IPs when you were
NATing to different interfaces on different ISPs (without your own block)
which is something I was able to do with 3 links (with three different IP
addresses) from 2 different providers.

   The scripts I attached with previous email provide per-flow load
   sharing using ipfw and natd.
   System is currently live.
   Regards, Graham


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