Routing Problem

Derek derekm.nospam at
Fri Feb 4 14:54:06 PST 2005

Gustafson, Tim wrote:
> I know it "can" be done.  I have a feeling that the FreeBSD TCP
> stack lacks the capability.  

If you are looking for multiple routes to the same destination, you are 
correct.  I believe that if you see the thread on net@ from 03/01/04 
with the subject "My planned work on networking stack":

  [] move IPv4 routing to its own optimized routing table structure and
     add multi-path and policy-routing options.  (planned)

I think this is the feature you are looking for: multi-path

I am also not sure of the status of this.

There are some hackish ways of dealing with this:

route add router1
route add router2
(or some such hideous incantation)

If you want to get real nasty, I would try some jiggery pokery with 

# receiving is done with public ips (all the same here as your current 
router1 vlan0 pubip1
router2 vlan0 pubip2
server  vlan0 pubip1/2

#transmitting is done through faked gateway 50% load each
router1 vlan1
router2 vlan2
server  vlan1/2
route add default

You'll need to be sure that both upstream providers will route either ip 
address though.  Also, there is no "dynamic" type of functionallity on 
this, if one of the links goes down, you'll lose 50% of your traffic. 
You could probably rig up a script to notify netgraph when the remote 
g/w goes down though.

I've never tried this, but it seems this wouldn't be a bad way to start 
if you've got some time on your hands.


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