Re: Thinking about "branes" for netbsd...

[Darren Reed <darrenr%netbsd.org@localhost>]

Dennis Ferguson wrote:
> On 5 May, 2012, at 17:55 , Darren Reed wrote:
> > Dennis Ferguson wrote:
> > > I'm aware of both of those.  I think you may be confused about
> > > what IP_BOUND_IF does (hint: last I looked it only effects
> > > where multicasts and broadcasts go).  IP_NEXTHOP does help if
> > > you think this is solved by having each application do its
> > > own routing (maybe the application could run DHCP to find out
> > > the next hop for that interface's default route too); if all
> > > applications did this then the kernel could get even simpler
> > > by eliminating all forwarding tables.
> > You want an application to send a packet back out the same
> > interface that the packet was received on. That amounts to
> > the application doing its own routing.
>
> See RFC 1122, section 3.3.4.2, the Strong ES model.  The routing
> operation is well-defined, the application doesn't have to be
> aware it is happening, but it needs a routing table per interface
> to implement it.

No, it does not.

The problem as stated is that the routing decision should
include the source address as part of the key for deciding
where to route a packet.

I'll grant that it is possible to read that as suggesting
that using a routing table per interface is the solution
but it is not the only solution to that problem.

Darren