nanog mailing list archives

Re: what about 48 bits?


From: "A.B. Jr." <skandor () gmail com>
Date: Mon, 5 Apr 2010 01:17:19 -0300

2010/4/4 Scott Howard <scott () doc net au>

On Sun, Apr 4, 2010 at 1:51 PM, Matthew Kaufman <matthew () matthew at>
wrote:

http://en.wikipedia.org/wiki/MAC_address

The IEEE expects the MAC-48 space to be exhausted no sooner than the
year
2100[3]; EUI-64s are not expected to run out in the foreseeable future.



And this is what happens when you can use 100% of the bits on "endpoint
identity" and not waste huge sections of them on the decision bits for
"routing topology".


Having around 4 orders of magnitude more addresses probably doesn't hurt
either...

Although even MAC-48 addresses are "wasteful" in that only 1/4 of them are
assignable to/by vendors, with the other 3/4 being assigned to multicast
and
local addresses (the MAC equivalent of RFC1918)

 Scott.




Wasteful in many ways.



While most of end user devices work with temporarily assigned IP addresses,
or even with RFC1918 behind a NAT, very humble ethernet devices come from
factory with a PERMANENTE unique mac address.



And one of those devices are thrown away – let’s say a cell  phone with
wifi, or a cheap NIC PC card - the mac address is lost forever. Doesn’t this
sound not reasonable?

A.b. --


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