Path: utzoo!utgpu!watserv1!watmath!att!pacbell.com!ucsd!usc!apple!hayes
From: hayes@Apple.COM (Jim Hayes)
Newsgroups: comp.protocols.appletalk
Subject: Re: Phase 1 vs. Phase 2
Message-ID: <48241@apple.Apple.COM>
Date: 18 Jan 91 08:37:07 GMT
References: <1991Jan17.205340.11378@pbs.org>
Organization: Apple Computer Inc., ECO Networking Group
Lines: 71

bhall@pbs.org (Dark Star) writes in article <1991Jan17.205340.11378@pbs.org>:
>
>We switched a couple of months ago.  I had been concerned about it but
>it turned out to be fairly easy.  We had 5 FastPaths, about 5 Macs with
>Ethernet cards and AppleTalk for VMS that needed to be updated.  
>
>Of course these were all in the same building and that helped a lot.
>

(These are my opinions, not my beloved employer's)

Apple no longer officially supports Phase I.  This is partly a Marketing
decision and partly an Engineering delusion.

I can say (quite plainly) that Apple ships the "Phase II Upgrade
Utility" and the "Phase II Node Identifier" with the AppleTalk Internet
Router because we couldn't convert our internal internet without them.
In fact, we still have a few disparate Phase I nets in use. (About 4
out of the 570 networks within Engineering).

It is important to note that Marketing is telling third party router
manufacturers to implement Phase II only.  Luckily most third party
router manufacturers are smarter than that.  Converting a large net
requires some healthy planning-- if your router vendor does not
support both protocols, life gets really hard.

Is it worth it?

For small networks (a few segments, a couple of zones) probably not.
The benefits gained using Phase II really only show up with large networks.

Some of the technical benefits:
	Zone-wide broadcasts use multicast addresses.
	RTMP now uses Split-Horizon updates for large backbones.
		This prevents routers on a backbone from re-telling
		the other routers something they've already heard from
		another router on the backbone.
	RTMP now uses "reverse poisoning" to propigate routing information
		for dead networks faster.
	NBP uses zone-wide broadcasts to resolve names and adds more
		wildcarding features
	The addressing scheme suports >65300 networks with an unlimited
		number of hosts per network. (actually 254 hosts per net
		number, but you can have multiple net numbers per each wire.)
	The addressing scheme supports multiple Zone names for each network.

We generally run only one network number per Ethernet and havn't bumped
into the 254 host limit.  We design our networks that way on purpose.

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.

As for third parties...  While I cannot endorse any third-party
products, I know of only one high-performance router vendor that routes
AppleTalk Phase I/II at the theoretical limits of Ethernet: Cisco
Systems.  We make extensive use their boxes internally along with our
own Internet Router and a few Kinetics Fastpaths for KIP.

If anybody is interested, I'll post a "Guts of Apple's Internal
Engineering Network" which contains some surprising numbers.  
Send some e-mail if you want to see it.


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

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