Transparant bridge with 2 nic's

[BrandyWine]

RFC's are not always very clear.

That RFC talks about "the forwarder" like it's a broker. RFC actually lumps L3 and L2 decision making into "the forwarder".

Data cannot move (actually fwd'd) between two devices w/o ARP from link layer, and the only way to L1 is from L2.

So if they want to call both L3 and L2 decision making "forwarding", then so be it, but when I trace the actual data it only moves via fwd'ing from L2 down to L1.

Routing engine says "next-hop is x.x.x.x, and use iface abc, now send down to link layer". That's all it does. ;)

(9) The forwarder performs any necessary IP fragmentation, as
        described in Section [4.2.2.7].  Since this step occurs after
        outbound interface selection (step 5), all fragments of the same
        datagram will be transmitted out the same interface.

   (10) The forwarder determines the Link Layer address of the packet's
        next hop.  The mechanisms for doing this are Link Layer-
        dependent (see chapter 3).

   (11) The forwarder encapsulates the IP datagram (or each of the
        fragments thereof) in an appropriate Link Layer frame and queues
        it for output on the interface selected in step 5