Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!TWG.COM!jb
From: jb@TWG.COM (John Bartas)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re: Sharing Interfaces
Message-ID: <8807280741.aa23266@Louie.UDEL.EDU>
Date: 27 Jul 88 21:05:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 45


     The recent postings about Sharing Interfaces have made me 
curious: which Packet Driver Spec are we talking about? 3COM, 
Novell, FTP Software Inc., and others have published details of 
their network hardware interfaces, but I have yet to see one that 
meets my needs as an implementor.

     For a packet driver spec to succeed, it needs several 
things:
- Wide acceptance by Software and Hardware Vendors.
- The ability to support multiple protocol stacks 
simultaneously.
- The ability to drive multiple interfaces simultaneously.

     3COM's and Novell's current products detail procedure calls to 
access the hardware, but they expect the application code to be 
linked with the driver code. There is no provision for me to 
write an application that will load in a DOS PC already running 
their networking and directly access the ethernet (or whatever) 
via their driver.

     Drivers written to FTP software's spec allow this, but my 
understanding of their spec is that it does not support multiple 
interfaces simultaneously. This won't work for routers and multi-
homed hosts.

     One solution to sharing drivers is to let one software 
package's driver layer use the other package as a link layer. 
This assumes that the other end on each connection is a similarly 
configured machine or that there is a gateway which has one 
interface similarly configured. On most PC LANs, this turns out 
to be a reasonable assumption. For example, Wollongong's 
WIN/Route product connects PC LANs to TCP/IP nets by using 
NETBIOS as a link layer between PCs and dedicating a single PC to 
routing packets to a regular TCP/IP link. One advantage of this 
approach is the TCP/IP software doesn't care what hardware or 
software it runs on, as long as it supports NETBIOS.

     3COM has announced their Vector interface as part of LAN 
manager will be available on DOS and OS/2. Vector has been 
evolving for years and seems to meet the criteria I set above. I 
imagine the other major vendors of PC Networks  will introduce 
similar standards and the industry will settle down to the few 
most widely accepted ones. 
---------------------------------------------------------------
John Bartas   Project Leader - The Wollongong Group.