elwell@tut.UUCP (09/29/87)
Here is a quick summary of the various types of gateway code for a
Kinetics Fastpath AppleTalk/Ethernet gateway:
AT.gw.srec:
This is the basic AppleTalk-over-Ethernet gateway code. This
is what Apple based EtherTalk on (with a few extra useful
things, such as a better AppleTalk address resolution
protocol). It encapsulates DDP packets in raw Ethernet
packets and sends them over the cable. It's fast and simple,
but only hosts or gateways that can understand
AppleTalk-format packets can handle it. This is what Alisa
Systems uses for their VMS AppleTalk product, and what (at
least our copy of) UNIX TOPS uses. Kinetics sells a set of
libraries and kernel drivers called K-Talk/Host that runs on
Vaxen, Suns, Pyramids, and probably others, that allows a host
to communicate using AppleTalk protocols. If you don't have
either this package or EtherTalk, it's main use is as a
high-capacity bridge connecting several different AppleTalk
Personal Networks. For instance, our installation here at OSU
uses this technology to link the nets in the CIS department
into an internetwork of over 200 nodes.
UDP.gw.srec:
This is similar in function to AT.gw.srec, but it encapsulates
AppleTalk DDP packets into UDP/IP datagrams instead of raw
Ethernet packets. This allows routers and gateways that
understand TCP/IP to automatically handle AppleTalk traffic.
It also handles a new type of DDP packet type that is used to
transmit and receive IP packets from an AppleTalk node, thus
allowing Macs to talk TCP/IP. There are public domain Telnet
and FTP programs available, of varying degrees of polish.
Columbia has a library called 'CAP' that allows UNIX machines
to generate and receive AppleTalk traffic, much in the manner
of K-Talk/Host, but you don't get any support. Any host that
can talk TCP/IP can talk to a gateway running this code, as
long as it doesn't require promiscuous ARP.
combgw.srec:
A combined gateway that performs the functions of both of the
above simultaneously, and nothing else. We have run it with
products that expect both of the above gateway programs without
problems. It is extremely reliable.
ddp.zip.srec:
A version of AT.gw.srec that handles zones (ZIP) better than
the original.
KIP:
A remarkable piece of code. It is public domain (you get
source), and it is a much better version of an IP gateway than
UDP.gw.srec. It handles subnetting (to the extent that
several K-boxes can be on the same IP subnet) and promiscuous
ARP very well. It works with CAP nicely, and allows dynamic IP
address assignment for AppleTalk nodes (no more per-node
configuration files).
If you live in a strongly TCP/IP oriented environment, I'd recommend
KIP. If not, I'd recommend the combined gateway. If vendor support
is more important than being able to futz with things at a deep level,
go with the combined gateway from Kinetics. They're good people.
--
Clayton M. Elwell
The Ohio State University Department of Computer and Information Science
(614) 292-6546 UUCP: ...!cbosgd!osu-cis!tut.cis.ohio-state.edu!elwell
ARPA: elwell@ohio-state.arpa (not working well right now)