Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!decwrl!ucbvax!VAX.FTP.COM!jbvb
From: jbvb@VAX.FTP.COM (James Van Bokkelen)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re: FTP Packet driver vs. Microsoft Lan Manager driver spec
Message-ID: <8812091615.AA14436@vax.ftp.com>
Date: 9 Dec 88 16:15:16 GMT
References: <8812080142.AA06758@vax.ftp.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 35

I have compared them.  Allow for my bias, but here are what I see as the
most important differences, in order:

1. Under DOS, the Microsoft NDIS-Mac spec requires that all binding (setting
up to receive and send packets) take place while CONFIG.SYS is running.  The
Packet Driver spec allows access_type() at any time.

2. The NDIS-Mac spec has no mechanism to un-bind; once you're receiving packets
you will continue to do so until a reboot (and if you just vanish, the world
will crash).  The Packet Driver spec allows release_type() at any time.

3. The NDIS-Mac spec makes no assumptions about packet acceptability
criteria; It calls you, and you look at the packet, and return an
indication of whether you want it.  The Packet Driver assumes the use
of a standard demultiplexing mechanism (e.g. Ethertype), and takes the
match criteria as an argument to access_type().  This also requires a
separate access_type()/release_type() for each packet type an application
wishes to handle.

4. The NDIS-Mac spec requires an additional component (the Protocol Manager)
to carry out the initial binding, over and above the MAC driver and the
application.  The Packet Driver spec only needs the MAC driver and the
application to function.

5. The NDIS-Mac interface is based on far calls through arrays of addresses.
The Packet Driver uses software interrupts for all but one function (the
packet-received upcall).

There are lots of other differences, but they are mostly implementation
details, not really relevant.  Neither spec attempts to hide the details
of the MAC layer packet (or special MAC-level protocols like ARP) from the
application.

James VanBokkelen
FTP Software Inc.