[e2e] use of MAC addresses

Craig Partridge craig at aland.bbn.com
Thu Apr 13 10:06:48 PDT 2006

In message <cd4882200604121035l2ce35b98ob27074726c4dfb55 at mail.gmail.com>, "Faha
d Dogar" writes:

>By using IP addresses for layer 2 routing, I am not implying the
>replacement of ethernet switches with routers. The ethernet protocol
>remains the same but the MAC address of every station is the same as
>its IP address. So these addresses have different interpretation (and
>subsequent forwarding) in a LAN compared to routing at layer 3. So we
>can block broadcast at layer 3 (routers) and allow broadcost at layer
>2 (ethernet switches). Again, I am asking purely from the
>functionality point of view. It may not be practical to do such a

I think you've just walked into the IP address = interface issues.  That
is, I can have a system with two MAC addresses and one IP address (although
it is painful).  In your scheme, I can't do that unless I'm sure the two
MAC interfaces are on disjoint (from the MAC-level) networks.

More broadly, you're raising a fun point but the details make my head hurt.

For instance, if I don't have a MAC address but have an IP address, does the
IP address stay with me when I move?  E.g., do I show up in Starbucks and
join the 802.11 wireless using my "assigned" IP address?  If so, we've
destroyed IP routing hierarchy (or we're using one of the myriad of mobile
IP protocols that everyone seems to find painful).  If I get a new IP
address from the 802.11 wireless network, how does it give me the new IP
address if I don't have any addresses???


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