[e2e] [mycroft@MIT.EDU: Re: use of MAC addresses]

Charles M. Hannum mycroft at netbsd.org
Thu Apr 13 17:17:28 PDT 2006

Whoops, fired from the wrong address before.

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Date: Thu, 13 Apr 2006 20:04:28 -0400
From: "Charles M. Hannum" <mycroft at MIT.EDU>
To: Joe Touch <touch at ISI.EDU>
Cc: "Charles M. Hannum" <mycroft at NetBSD.org>,
	Fahad Dogar <fahad.dogar at gmail.com>, Ted Faber <faber at ISI.EDU>,
	end2end-interest at postel.org
Subject: Re: [e2e] use of MAC addresses
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On Thu, Apr 13, 2006 at 03:45:23PM -0700, Joe Touch wrote:
> The "" in your response is important; many "shared media" these days
> aren't. That doesn't mean the MAC address isn't still useful, but it
> does mean it may not be necessary.

Sure.  As I pointed out before, lots of point-to-point protocols don't
have a notion of "link layer" addresses.  Take PPP, for example -- for
purposes of assigning addresses, it typically uses a combination of
{POP,user} as a unique identifier.  This works because the owner of the
POP can guarantee that the users are unique.

In a hypothetical setup where we have people roaming around between
different APs/POPs/whatever using possibly-conflicting identifiers,
this is all going to fall down.  Having a globally unique identifier
simplifies the problem tremendously.  What's the advantage of changing
it?  Some mythical notion that MAC addresses are "outdated" isn't going
to cut it.  Besides, we've already discussed several useful purposes
that the MAC address serves, so it's rather clearly *not* outdated.

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