Subject: Re: ipNetToMediaPhysAddress

From: [email-masked]
Date: Thu, 20 Nov 97 10:51:31 EST

Tim,

>I thought that it was also agreed that using the length of an object
>to determine its type was a bad idea.  [If not, we should have concluded
>as much.]

Not so. After debating this on the list along with Keith and Kaj I
was convinced to forget about defining a format object. It was pointed
out to me that neither the ILMI MIB nor the ATOMMIB MIBs define
a format object and that the length of the OCTET STRING is sufficient
for determining address format.

Ken

---

From: Paul Koning <[email-masked]>
Date: Thu, 20 Nov 1997 11:08:46 -0500

>>>>> "kennethw" == kennethw  <[email-masked]> writes:

 kennethw> Tim,
 >> I thought that it was also agreed that using the length of an
 >> object to determine its type was a bad idea.  [If not, we should
 >> have concluded as much.]

 kennethw> Not so. After debating this on the list along with Keith
 kennethw> and Kaj I was convinced to forget about defining a format
 kennethw> object. It was pointed out to me that neither the ILMI MIB
 kennethw> nor the ATOMMIB MIBs define a format object and that the
 kennethw> length of the OCTET STRING is sufficient for determining
 kennethw> address format.

ILMI is not relevant because it only handles AESAs which are always 20
bytes.  The issue is with the ATOM MIB and the NetToMedia table
equally (ATOM isn't precedent, it's part of the issue).

Suppose the ITU defines another "native" address type with a length
other than 8 bytes, or extends the E.164 definition to allow longer
addresses.  Then the existing implementations are affected in a way
far messier than they would have been with a format type.

Suppose it became possible to have an AESA address and E.164
subaddress.  Then the "encoding" currently defined is ambiguous
(because you'd have a 28-byte concatenated address).

	paul

---

From: Keith McCloghrie <[email-masked]>
Date: Fri, 21 Nov 1997 00:00:26 -0800 (PST)

Paul,

> equally (ATOM isn't precedent, it's part of the issue).

It's the interfaces group which set the precedent (in 1988) that an
interface's address (ifPhysAddr and atPhysAddress) is a single value
without a format identifier.  atPhysAddress was deprecated in MIB-II
in 1991 in favour of ipNetToMediaPhysAddress.

> (because you'd have a 28-byte concatenated address).

Let's cross these bridges if/when they occur.
 
Keith.