Path: utzoo!utgpu!watserv1!watmath!att!linac!uwm.edu!zaphod.mps.ohio-state.edu!usc!apple!hayes
From: hayes@Apple.COM (Jim Hayes)
Newsgroups: comp.protocols.appletalk
Subject: Re: Phase 1 vs. Phase 2
Summary: Whoops.
Message-ID: <48271@apple.Apple.COM>
Date: 19 Jan 91 05:20:57 GMT
References: <1991Jan17.205340.11378@pbs.org> <1991Jan18.175928.11397@pbs.org>
Organization: Apple Computer Inc., ECO Networking Group
Lines: 69

First of, before I answer this question, I should have clarified myself when I
said that Apple does not support Phase I.  I meant it strictly in the
router/WAN context.  Of course LocalTalk (which is Phase I) has not changed
and is still vigorously supported by Apple on all platforms. 
[Thanks to Jim K. for correcting me...]

bhall@pbs.org (Dark Star) writes in article <1991Jan18.175928.11397@pbs.org>:
>> We do, however, make extensive use of the multiple zone name per
>> network feature which allows us move network services to anywhere on
>> the network and still keep the original zone name while people get used
>> to the new location.  We tend to reorganize and move quite often, so
>> this feature comes in handy.
>> 
>
>How does this work?  "Who" supplies the zone names?  The Macs themselves?
>Routers?
>

First off, let me clarify why we use it.  We have a few file servers
that contain site-licensed software.  Given Apple's great propensity
toward reorganization, the file servers are a moving target in terms of
where they physically sit.  But it doesn't matter, the zone name moves
with them and they still look like they're in the old spot.  Note that
we don't replace the zone name in the new location, we just *add*
another zone to that location's net.

The Phase II routers are responsible for keeping track of zone names.
The Mac's only care about the zone they appear to be in and the nearest
router.

It works by using the new "Zone Multicast Address" which provides the
ability to send name lookup requests to specific "interested" parties
on the net.  If there were many routers on a backbone and only two
handled a particular zone, only those two would be bothered when folks
ask about that zone.

Note, however, that a zone name cannot be "disjoint" through routers.
Specifically, if you have three nets separated by routers and they're
all in the No Parking zone, you can't create an additional Zone on each
end without it also appearing in the middle.   I.e. This is not
allowed:


<---Net A---> [router] <---Net B---> [router] <---Net C---> 
 No Parking             No Parking             No Parking
 Free Trade              End Zone              Free Trade

For things to work properly, the Free Trade zone must appear on all the 
routers in between.  This works:

<---Net A---> [router] <---Net B---> [router] <---Net C---> 
 No Parking             No Parking             No Parking
 Free Trade             Free Trade             Free Trade
                         End Zone

[Side Note: If you have more than one zone on a wire, you can put your
Macintosh into any of those zones by using the "Network" cdev in the
control panel.  Clicking on the EtherTalk or TokenTalk icon will bring
up a list of available zone names...  This is useful for putting fileservers
on the same wire into logical groups.]

Anyway, I hope this doesn't add any more confusion to things. :-)


-- 
Jim Hayes, Network Manager (I manage the hardware, not the network group)
Engineering Network Services, Apple Computer Inc.

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