Picking an IP multicast address

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

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.

The problem I have is picking the multicast IP address. I know some
are reseerved (all hosts, all routers, etc.) and I know there are
protocols for having one assigned dynamically on a network at run
time. But, as I said, these devices are too stupid to negotiate for
that assignment. Is there one or more multicast IP addresses that are
intended to be used like network 10 (10.192.x.x, 10.168.x.x, etc.) for
local, private communication?

Thanks for any pointers.

Chris
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More about picking multicast address
  1. 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
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