Connecting networks

[Ian Smith]

On Wed, 12 Dec 2007, Alaor Barroso de Carvalho Neto wrote:
 > 2007/12/12, Ian Smith <smithi at nimnet.asn.au>:
 > > Should be 'defaultrouter', but then it's a route to an apparent local
 > > router, whereas your em0 appears to be your public internet connection?

 > Yes, it's default router, like I said I was not in my work then I wrote by
 > myself this lines, like I didn't touch the defaultrouter line since the
 > install I guess it's correct, my fault. Yes, em0 is my public connection,
 > but it's not connected to the external network yet, that's why my default
 > router is 192.168.1.80 (that is my current gateway, connected with the
 > external world, and who I want to be replaced by this BSD box)

Ok.  Will this box be connecting some/all of these subnets to the world?

 > > I think this is at the core or your issue.  Let's assume that a box on
 > > xl1, say 192.168.2.100, wants to talk with a box on xl2, say 10.10.0.100
 > >
 > > 192.168.2.100 needs either your box (192.168.2.90) as its default route,
 > > or it needs to have added a specific route for 10.10 via your box.
 > >
 > > Similarly, 10.10.0.100 needs either your box (10.10.0.50) as its default
 > > route, or it needs to have added a specific route for 192.168.2 via you.
 > >
 > > Unless both of these conditions are true, packets will not get (or get
 > > back) to where they're supposed to go, even if your box setup is all ok.

 > The The machines is 192.168.1 aren't using my BSD box like it's default
 > gateway it, so it may be the problem? But, like I've said, this is the
 > second time I try to put the things to work, the first time I've set the
 > 192.168.1 machines to use my bsd as default gatway and didn't work also. But
 > I gonna change it to test again. My machines in 192.168.2 are all using
 > 192.168.2.90 as it gateway already.

Well, as above.  In your scenario all of the boxes in each of your 3
local subnets will have to route packets for the other 2 subnets via
your box's address in that subnet, either as their default route or by
adding specific routes for each of the 'foreign' subnets via your box. 

Tricky unless you have admin control of all boxes' routing, especially
in an 'anything that can happen will happen' environment like a campus,
unless this box is going to be the default route for all subnets anyway?

cheers, Ian