djh@cs.mu.oz.au (David Hornsby) (01/30/91)
The following is in response to recent postings about AppleTalk Phase 1 and Phase 2, and several people who seemed to be concerned that CAP does not yet work with Phase 2 networks. I hope it helps ... CAP does not currently support EtherTalk Phase 2. However, it is possible to use CAP in a Phase 2 environment, with some provisos. Traditionally, the CAP transport mechanism uses UDP/IP packets. This is called IPTalk (also known as KIP) and is a "non-extended" (1 net number and 1 zone name) network. CAP with IPTalk can run on a LARGE variety of UNIX platforms. On some Ultrix and SunOS machines, CAP can also produce EtherTalk Phase 1 packets directly (using Native EtherTalk support or UAB - the UNIX AppleTalk Bridge). EtherTalk Phase 1 is also a "non-extended" network. Macintoshes on EtherNet can speak EtherTalk Phase 1 or Phase 2. EtherTalk Phase 2 networks are always "extended", allowing multiple network numbers and zone names on a single cable. An "extended" network can be "restricted" to have one net number and one zone name. This permits the Phase 2 routing information to be translated into Phase 1 routing packet format. This is not otherwise possible. For completeness, LocalTalk networks can use either Phase 1 or Phase 2 AppleTalk packets, but such networks are always "non-extended". In a brief summary of AppleTalk Phase 1 and Phase 2 differences on LocalTalk, routing information (RTMP) packet formats are different. NBP packets allow a new character (approxEquals or 0xc5) for partial NBP name and type matching. Nodes are no longer required to send to the last RTMP sender that they heard from, rather, they can choose to send to the "best" router. There are other differences for Phase 1 and Phase 2 EtherTalk packets on EtherNet. These differences relate mainly to delivery mechanisms. If you use CAP with IPTalk and *NO* AppleTalk routing over IP (ie: via an IP link between IP gateways) then you can use CAP with Phase 2, "extended" networks with no restrictions (except of course, that you must have an AppleTalk Gateway capable of talking IPTalk and EtherTalk Phase 2). On the other hand, if you are using CAP and IPTalk with AppleTalk routing over IP, or CAP with EtherTalk Phase 1, then your Phase 2 networks must all be "restricted" and you need to have a gateway capable of operating in "transition" mode (the problem with the first case is due to the way IPTalk works rather than CAP. IPTalk 2 is under development and will solve this). The gateway translates the packets from one format to another. Suitable IPTalk/Phase 2 gateways are the Webster MultiPort Gateway (running Megan 2.1 or later) and the Shiva FastPath 4 (running KSTAR 8.0 or later). Most earlier versions of the gateway code will happily translate from IPTalk to either Phase 1 or LocalTalk. If you don't have a hardware gateway at all, you can currently only use CAP with UAB or Native EtherTalk (both Phase 1) and other *Phase 1 ONLY* nodes. Thanks to Tom Evans and Robert Elz for the proof-reading. David Hornsby ...!uunet!munnari!djh Professional Officer djh@munnari.OZ.AU Department of Computer Science "The home of Multigate" +61 3 344 4044 The University of Melbourne, Parkville, 3052, Victoria, Australia.