Multiple default routes / Force external routing

Steve Bertrand steve at ibctech.ca
Tue Apr 14 05:55:02 PDT 2009


Julian Elischer wrote:
> sthaug at nethelp.no wrote:
>>> I've poked about for weeks and asked similar questions in
>>> -questions and elsewhere without avail. Probably using the wrong keys
>>> to search and ask:
>>>
>>> I have set up a box with various vlan interfaces on it. I naively
>>> expected to be able to set individual "default" routes and route
>>> between them via an *external* router (and filter packets there etc.)
>>> but somehow all packets seem to "short-circuit" locally, and I don't
>>> seem to be able to see why this is so and how I prevent that.
> 
> I think you are rather confused about what Multiple FIBs is..
> All it is is teh  ability to make a packet use a particular
> FIB on it's outgoing path. There is not such thing as an interface
> being "In" a FIB. All interfaces are still visible to the routing code
> by default, and The IP stack still knows about them.I think the IP
> stack set's the 'loopback' flag on a packet regardless of the FIB
> selected if teh dest is one of its own addresses.
> 
> What you want is VIMAGE.

Perhaps the OP should rephrase his desire.

To me, it sounds like he wants to turn the FBSD box into a VLAN
aggregator, and then "trunk" the VLANs to an external router to route
between the VLAN subnets.

If this is the case, then the default route that points to the
'external' router would need to be applied on the devices within each
VLAN subnet, not on the VLAN aggregator device(s) themselves.

Do I understand what you are trying to do correctly?

Steve


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