Picking an IP multicast address

Archived from groups: comp.dcom.lans.ethernet (More info?)

Chris Nelson wrote:

> I'm building a network of fairly stupid devices. Most if not all
> communication with them will be via MAC-addressable frames. They
> aren't big or smart enough to have an IP stack, complex, heavy-weight
> discovery protocols, etc. BUT, I also need 'Windows-based tools to be
> able to reach these devices and _that_ is facilitated by writing to a
> multicast _IP_ address and letting the stack just do the normal thing
> of mapping that IP into a multicast MAC address.

20 years ago diskless machines could boot with RARP and TFTP/UDP
in maybe an 8K ROM, with the disk boot code in there, too.

I really find it hard to believe that even the smallest machine
today couldn't do it. (Though I would hope BOOTP or DHCP instead
of RARP.)

UDP is much easier than TCP. TFTP was designed to be easy to
implement in a small ROM.

The only system that I legitimately believe should be able
to work without IP is the system to power up machines based
on a special ethernet frame. Only the NIC is available to
process it, as the machine is off!

-- glen