Path: utzoo!attcan!uunet!snorkelwacker!usc!ucsd!ucbvax!FTP.COM!jbvb
From: jbvb@FTP.COM ("James B. Van Bokkelen")
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re:  DesqView/Windows3.0 and Packet Drivers - A Modest
Message-ID: <9009191629.AA14043@ftp.com>
Date: 19 Sep 90 16:29:12 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: jbvb@ftp.com
Organization: The Internet
Lines: 16


    Can native NDIS do this?  I seem to recall hearing that under NDIS each
    received packet is passed to all the protocol stacks to process or not
    process, as desired.  If that's true, each TCP/IP stack could look at
    only the packets with its IP address.  A kludge...

Yes.  It only works as long as there are no packets which want to go
to both protocol stacks (e.g. ARP replies, RIP broadcasts, etc.).
NDIS doesn't guarantee that a packet can be received by more than one
protocol.  You also would either parse all the layer's headers twice,
or wind up spending a *lot* more time in the receive_lookahead or
receive_chain upcall than the MAC driver's designer assumed you would
while you check the IP and TCP checksums.

James B. VanBokkelen		26 Princess St., Wakefield, MA  01880
FTP Software Inc.		voice: (617) 246-0900  fax: (617) 246-0901