Ref: 99980022
Title: Information on the Intelligent LAN Adapter (ILANA) Card
Date: 1/1/88

Copyright 3Com Corporation, 1991.  All rights reserved.

Intelligent LAN Adapter (ILANA) Card

Run 3Com's 3+ Network Operating System while supporting up to
eight terminal sessions!  Intelligent Local Area Network Adapter
card turns the personal computer into the business workstation.

The PC has a memory problem

With Terminate and Stay Resident (TSR) software and various
device drives (printers, serial communications) eating up
available RAM, applications are finding less and less room to
run.  An IBM PC with 640K bytes of memory and running 3Com's
3Plus workstation drivers, Microsoft Windows, and Microsoft Word
does not have enough remaining memory to run the Word spelling
checker.

The PCs is also overworked.

At the same time, users are demanding more and more performance.
Considerable processing is necessary to provide an interface to a
10 Mbps LAN.  All LAN traffic must be constantly monitored;
pertinent traffic must be acknowledged; established traffic must
be maintained.  In addition, various levels of communication
(from data link level to presentation level) must be tied
together perfectly, making them invisible to the end-user
application.  PC's were not designed to directly interface to a
network.  In fact, the COM1 serial port running 9,600 bits-per-
second constant data traffic can completely consume an IBM PC.
Is the PC doomed to collapse under the pressure?  Maybe, but not
from the network.  Now the enormous processing requirements of PC
networking have been removed from the overburdened PC by the
intelligent network adapter card.

First-generation network adapters provided enough processing
power to avoid data link and most network level processing on the
PC.  However, most transport and session level protocols were
handled by the PC.  This necessitated a lot of code, over 100
kilobytes (KB), in the PC transient memory and considerable
processor overhead.  Without the processing power, the idea of
multiple network connections to different network devices (hosts,
printers, Public Data Networks) was only a dream.

ILANA-Intelligent LAN Adapter

The ILANA is the first in the next generation of network adapter
cards for PCs.  All TCP/IP protocols, including Telnet, run on
the ILANA card.  Only the interface (user or program) portions of
the network control code run in the PC.  This increases the PC's
performance and drastically reduces the PC memory required by the
adapter.

The PC accesses the ILANA board through a shared memory
interface.  In other words, a portion of the ILANA's 512K of RAM
appears to the PC as memory on the PC bus.  This is different
from DOS memory, which is only the first 630K of the 1M byte of
memory space in a PC.  The ILANA also has access to this memory
(thus it is shared).  This portion of RAM is also referred to as
the window, and its size can be adjusted between 64 KB and 128
KB, depending on how much address space is available in the
user's PC.  The beginning address of the window in PC memory,
referred to as the base address, is selectable as well.  The
window is used for communications buffer space, and access to the
window is coordinated using a PC interrupt.  The ILANA supports
any unreserved PC interrupt level.

The ILANA board does not support DMA transfers.  This is not an
oversight.  The window has been designed to be large enough so
that data is normally not copied between PC memory and the
window.  Instead, data is placed directly in the window by PCS/1
software (see New Products), for transmission once the entire
packet is complete. (In addition, DMA transfers in a PC/AT are
slower than memory copies, due to the design of the PC/AT.  Most
other attempts at intelligent adapters do not have windows large
enough to allow this type of implementation and have to copy data
between the window and PC RAM.

The ILANA board is available in both the PC/AT (XT/286) form
factor and the PC/XT form factor.  The primary difference between
the two is the width of the PC bus.  The PC/AT form factor has a
16-bit wide bus, so that two bytes are transferred across the bus
when a memory location is accessed.  The PC/XT form factor has an
eight-bit wide bus so that only a single byte is transferred when
a memory location is accessed.  In theory, the PC/AT bus should
offer higher performance than the PC/XT bus.  In practice, there
is no significant difference because the PC bus is not a
bottleneck.  A more important difference is that the PC/AT
version allows the choice of a 64K window or a 128K window,
whereas the PC/XT version only has a 64KB window.  The bigger the
window, the more communications buffers and the more available
sessions.  The 64 KB window configuration can support 4 Telnet
sessions, 4FTP sessions, and 24 NETBIOS sessions.  The 128 KB
window configuration can support 8 Telnet sessions, 8 FTP
sessions, and 48 NETBIOS sessions.  In mose cases this is
immaterial as well, except for PCs that function as servers with
a NETBIOS application.

The PC/AT version supports Ethernet (802.3) and Bridge Broadband;
while the PC/XT version supports Ethernet (802.3) and thin
Ethernet (a.k.a. Cheapernet).  Note that the PC/XT version will
operate in an AT-call machine if a thin Ethernet adapter is
desired.  The reverse is not true.  A PC/AT version will not work
in a PC/XT.  The PC/XT version and the PCS/1 software will work
in the new IBM PS/2 Model 30.

Network Software, PCS/1

ILANA network software comprises into two components.  The first
is the network software, which handles all of the protocol
processing as well as provides communication services to
application software.  The second component, discussed later, is
the application software, which performs the actual presentation
services to the PC user.  The network software, although in large
part invisible to the user, is the basis for the flexibility and
sophisticated capabilities of the PCS/1.

Protocols

The TCP/IP protocols, including Telnet (client only), TCP, IP,
UDP, ARP, Bridge Network Management, and NETBIOS, run on the
ILANA board.  This provides the two basic advantages of the
intelligent adapter.  First, the PC processor does not have to do
protocol processing, increasing performance and freeing the PC
processor for application processing.  Second, PC memory
consumption is dramatically reduced.  Although this is normal for
an implementation using an intelligent adapter, it is unusual for
Telnet and NETBIOS to be run on the adapter (most implementations
run these on the PC).  Bridge has spent a considerable effort
implementing these protocols on the ILANA board in order to
provide multiple session support and to further off load the PC.
In fact, only the software interfaces and the user interface run
in the PC.  Everything else runs on the ILANA.  For all practical
purposes, the ILANA card with the PCS/1 network software running
on it, is equivalent to a CS/50 embedded inside the PC.
Application software allows the PC user to access this personal
communications server via the software interfaces provided by the
memory-resident portion of the PCS/1 software.

The interface to the ILANA board is a driver (1KB) that is loaded
by DOS when DOS is first booted.  The ILANA board itself is
loaded by a DOS applicaiton that runs immediately after all
drivers have been loaded.  This loader reads that ILANA program
from the PC's disk and moves it into the ILANA's RAM.  During
this phase, DOS also loads the Terminate-and-Stay-Resident (TSR)
program that provides the software interface to the PCS/1
protocols and a TSR program that provides the Bridge Application
Program Interface.

BAPI

The Bridge Application Program Interface (BAPI) provides a way
for network applications developers to offer customer solutions
for network management and other complex communications problems.

The Bridge Application Program Interface serves as an interface
to Telnet that application software, such as a terminal emulator,
can use to provide a PC user with TCP/IP connection services.
This interface is used by Bridge-supplied emulators, including
the simple terminal emulators, PCSVT, and PCS3270, as well as by
third-pary terminal emulation programs.  BAPI is similar to the
Interrput 14H Emulation supported by EtherTerm, but differs in
several ways.  First, extensions have been added to allow
application software to transfer blocks of data to the network,
improving performance, and to directly control session
establishment and termination, increasing flexibility.  Second,
BAPI provides a CS/1-like user interface to applications that do
not use the session control extensions.  In addition, BAPI
provides a mechanism to allow multiple session support.  BAPI is
a key component because it allows compatible terminal emulators
to emulate almost any terminal, from a simple TTY to an IBM 3270
display station.

NETBIOS

NETBIOS emulation provides a mechanism for industry-standard
software to communication over the LAN.  NETBIOS is a standard
established by IBM (developed by IBM and Sytek) that defines an
interface to the PC Basic Input/Output System (BIOS) extension.
It allows application software to transmit and recieve packets
over a local area network.  The NETBIOS specification defines a
software interface to the transport and datagram mechanisms of
the LAN hardware.  The Intelligent LAN Adapter provides the
flexibility to implement the NETBIOS interface in software, thus
the term NETBIOS emulation.  All of the NETBIOS functions defined
by the IBM are supported by the NETBIOS emulation.

Bridge's NETBIOS emulation utilizes TCP/IP to provde NETBIOS
services to application software.  This implementation of NETBIOS
over TCP/IP fully conforms to the standard defined by RFC
(Request for Comment) 1001 and 1002.

NETBIOS only defines an interface to the transport and datagram
mechanisms of the LAN.  It does not define the underlying
mechanism, which in this case is TCP/IP.  Other implementations
of the NETBIOS interface use other protocols to provide the
NETBIOS services to applications; for example, 3COM's
implementation which uses XNS and IBM's implementation which uses
a proprietary set of protocols.  Thus one vendor's NETBIOS will,
in most cases, not work with another vendors' NETBIOS.  An
exception to this occurs when both vendors' NETBIOS conform to
RFC 1001 and 1002.  In fact, the purpose of RFC 1001 and 1002 was
to define a standard implementation of NETBIOS using TCP/IP
protocols, so that different vendor's NETBIOS implementations can
be made compatible.  This is currently the only independent
specification for NETBIOS implementation.

3Com/Novell Drivers

3Com's 3Plus and Novell's Netware software allow sharing of PC
resources, such as disk drives, files and printers over a LAN.
The ILANA's PCS/1 software can provide a compatible driver for
either (that is, one 3Com driver or one Novell driver).  The
driver makes the ILANA appear to the 3Com or Novell software as a
non-intelligent adapter with buffering capability.  Everybody
thinks they own the interface, but the ILANA is smart enough to
manage the interface and provide services to LAN applications.

Only one of these two, either 3Com or Novell software, may be
installed in a PC at any one time.

The full set of 3Com/Novell software runs in the PC, as it would
with any other adapter card, and this has two benefits.  First,
the 3Com or Novell software can communicate with any other device
on the network that runs the 3Com or Novell software, with
whatever adapters installed to allow communication.  Second,
since 3Com and Novell use XNS protocols, a PC with either
installed can be said to support multiple protocol stacks.  This
is important because LAN users are interested in being able to
have access to as many LAN services as possible.  More
importantly, however, this can ease the transition to TCP/IP from
XNS.  When 3Com's 3Plus software is installed with the ILANA and
its software, EtherTerm can be run in the PC (it uses the same
3Com drivers) to provide access to XNS Communications Servers
until the Communications Servers are migrated to TCP/IP.

ASYNCHRONOUS TERMINAL SERVICE

Bridge provides two standard TTY terminal emulators and an
optional VT100 emulator with the ILANA and PCS/1 Software Engine.
All three use the BAPI interface.  The two TTY terminal emulators
can be used in conjunction with a DOS driver called ANSI.SYS that
lets the PC emulate and ANSI (VT100subset) terminal.  The
GraphPoint TNET-05 product works in the same way and can also be
used with the standard TTY emulators.

TCP/IP FILE TRANSFER SERVICE

TCP/IP file transfer service, supplied with the PCS/1 Software
Engine, is a client-only implementation of TCP/IP FTP.  The
complete set of FTP commands found in most commercial
implementations of FTP are supported.  This makes for some
interesting possibilities when running PC networking software,
such as 3Plus, and the PCS/1FTP.  By using FTP to direct a file
to a 3Plus shared volume, a file can be copied directly from an
TCP/IP host to a XNS file server (i.e., 3Server3).

3270 EMULATION SERVICE

The 3270 emulation service is an optional software product for
the PCS/1.  This is the same 3270 emulation software used in
EtherTerm/3270, except connections are established by specifying
the name when invoking the emulator instead of using EtherTerm
menus.

LOCAL AREA NETWORK MANAGEMENT SERVICE

Network management service is accessed through the PCSMGR program
(part of the PCS/1 network software).  Invoked from the DOS
prompt, it provides a CS/1-like user interface, including context-
sensitive help, to perform local network management activities.
The PCS/1 software lets either 3Com or Novell software run in the
PC and access existing servers on an Ethernet.  This also allows
a graceful migration from XNS to TCP/IP.  The PCS/1 can even be
used in non-Ethernet 3Com and Novell environments.  Both vendors
offer a way for the server to attach to more than one network
(standard for Novell; 3Com offers NetConnect).  For example, in a
network that has a Novell server using Arcnet, you can put an
Ethernet card in the server (with the Arcnet card) and let PCS/1
users access the Novell server over the Ethernet.






