Exploring IBM PC Servers in an ATM Environment

By Franchesca Collins

'Asynchronous Transfer Mode (ATM) is an emerging technology that affords greater throughput and support of diverse media for high demand networks and PCs. The IBM PC Server runs network operating systems that are not written to support native ATM networks. This article presents a solution, LAN Emulation over ATM, and tells you how to implement it wit some of the network operating systems supported by IBM PC Servers.'

I have had to change my definition of "ATM." During a recent discussion, several of my peers said that ATM is the "hottest thing going." My reaction was that my co-workers must be out of touch -- after all, ATMs have been around for a long time! I use my plastic ATM card on a regular basis. After that discussion, I felt I was the "hippest," most up-to-date person in the group.

During a technical planning session, several days later, I suddenly realized that ATM now means more tha njust "automatic teller machine." The "hottest thing going" is instead the rapidly evolving networkin concept of "Asynchronous Transfer Mode."

The first ATM product hit the market in 1994, and they have been proliferating since that time. The forces behind ATM include high-capacity, high-demand workstations, and servers such as those in the IBM PC Server family.

IBM PC Server in the Traditional LAN Environment
The IBM PC Server supports the following network operating systems (NOSs):
 * IBM OS/2 Warp
 * Novell NetWare
 * Microsoft Windows NT
 * SCO UNIX
 * Banyan Vines

Each of these NOSs is a LAN application that conforms to traditional LAN topologies. That is, it assumes a LAN type of token-ring, Ethernet, fiber distributed data interface (FDDI), and so on. The protocols used by these physical media include TCP/IP, NetBIOS, NetBEUI, and IPX/SPX. Each of these protocols works well in the shared medium for which it was designed. Client/server implementations that use any of the NOSs supported by IBM PC Servers fall into a local category, remote category, or both.

Figures 1 and 2 represent local and remote LAN implementations. Local LAN implementations usually accommodate intra-communication between clients and one or more servers; the servers can range from file servers to application servers, as shown in Figure 1. Remote LAN implementations accommodate communication between clients and servers in two different physical locations, as illustrated in Figure 2.

Regardless of which LAN implementation is applied, the problem of increasing throughput (that is, giving users better response time) is always present. With the increasing bandwidth required by servers, ATM is a solution.

Faster than a Speeding Bullet
Token-ring, Ethernet, and sometimes FDDI networks reign supreme as the networking topologies of choice in today's client/server environments.

When token-ring was first introduced, it was considered fast at 4 Mbps; however, 16 Mbps soon became the standard for ring speed. Then early token release was added to speed things up even more.

Meanwhile, in the Ethernet world, 10 Mbps networks rapidly exploded to 100 Mbps networks.

Whether you are dealing with 4 Mbps or 100 Mbps, in a LAN environment the nMbps must be shared among all devices connected to the LAN. Traditional LAN topologies have just about reached the maximum for transmission rates. In an attempt to maximize throughput, we have streamed, jetted, dualed, and quadded the adapters used in devices on the LAN.

ATM, being a high-speed switched network, nicely addresses the throughput issue. In theory, all devices installed with 155 Mbps adapters can concurrently transmit at 155 Mbps, yielding greater overall throughput. This is a slight stretch, but the point is that no single device must wait for another before transmitting data on an ATM network. (Switched Ethernet is another alternative, but is beyond the scope of this article.)

Adding ATM to the Picture
Most environments are traditional LAN installations. The NOSs supported by IBM PC Servers are written for communication using traditional LAN protocols and technologies. To add ATM to the current LAN picture, you must have a "glue" known as ATM LAN Emulation (LANE). Although, in some cases another option is Classical IP, this article focuses on ATM LAN Emulation.

Components of ATM LAN Emulation
ATM LAN Emulation (more precisely, LAN Emulation over ATM) comes in proprietary implementations and ATM Forum implementations. Regardless of which implementation, the goal is to enable LAN applications and protocols written for traditional LAN topologies to run on an ATM network without modifications.

IBM developed a proprietary implementation of LAN Emulation over ATM prior to the existence of the ATM Forum implementation. The proprietary implementation is now being phased out in favor of the ATM Forum's LAN Emulation over ATM, the standard to which most ATM vendors adhere.

The ATM Forum LAN Emulation consists of: The emulated LAN components collectively:
 * LAN Emulation Client (LEC)
 * LAN Emulation Server (LES)
 * LAN Emulation Configuration Server (LECS)
 * Broadcast and Unknown Server (BUS)
 * Resolve MAC addresses to ATM addresses
 * Replace the connectionless operation of traditional LAN with ATM's connection-oriented approach
 * Mimic the broadcast and multicast characteristics of a traditional LAN in a connection-oriented ATM environment

An emulated, or virtual, LAN requires a LAN Emulation Client running on each device on the network. The remaining components (LES, LECS, and BUS) can be distributed over different physical devices, or can exist collectively in one physical system. Either way, they are three distinct functions. In Figure 3, a virtual LAN consists of IBM PC Servers, RISC/6000 systems, an ATM switch, and a bridge. Each of the IBM PC Servers and RISC/6000 systems is running LEC services. The switch in this case runs the LEC, LECS, BUS, and LES services. The PC Server provides routing services for the PCs attached to the token-ring LAN. The bridge runs the LEC service and connects the token-ring, Ethernet, and FDDI LANs to the ATM emulated LAN.

ATM Addressing Versus LAN Addressing
An obvious distinction between a traditional LAN and ATM LANE is in the addressing. In traditional LAN environments, a six byte media access control (MAC) address is used. The ATM address, on the other hand, is 20 bytes, six of which make up a MAC address. The ATM address is made up of the following components:
 * 13-byte switch prefix
 * 6-byte MAC address
 * 1-byte selector

Figure 4 contains a sample of the entire ATM address, with periods separating the logical components. ATM addressing is automatic if you use Interim Local Management Interface (ILMI) or another registration procedure service. In fact, only the six-byte MAC component is static. You can manually specify the ATM address for every LEC, LES, LECS, or BUS in an emulated LAN, but it will soon become an administrative nightmare. You also have the option of specifying the MAC portion of the ATM address, as you would have in a traditional LAN environment.

Installing ATM LANE for PC Server Support NOSs
Installing ATM LANE for PC Servers consists of installing the physical adapter, the NOS-specific device driver, and LAN emulation software. At a minimum, the LAN emulation software you install on the server should consist of the LAN emulation client services.

Installation under OS/2 and OS/2 Warp
Installing ATM device drivers under OS/2 and OS/2 Warp requires modifications to the PROTOCOL.INI and CONFIG.SYS files. The Multi-Protocol Transport Services (MPTS) program automatically configures and installs LAN-based communications adapters and protocols for the OS/2 and OS/2 Warp environments. You have the option of manually installing device drivers, but the task can be tedious, so use MPTS whenever possible.

ATM adapters do not appear in MPTS's default adapter list. Follow these steps to add the ATM adapter and desired protocols under MPTS.

1.	Execute the MPTS program from the desktop or from the OS/2 folder.

2.	When you see the Multi-Protocol Transport Services logo panel, select OK.

3.	In the Multi-Protocol Transport Services panel, select the Install pushbutton.

4.	When the Install Additional Network Device Drivers panel appears, insert the ATM adapter's OS/2 device drivers diskette for the adapter you have installed. (This disk should have come with the adapter.) Select OK.

5.	Select OK in all the installation completion panels until the Multi-Protocol Transport Services panel reappears. Select Configure.

6.	In the Configure panel, make sure that the LAN adapters and protocols (LAPS) radio button is selected, then select Configure.

7.	In the LAPS Configure panel, select the newly added ATM adapter from the network adapter list, then select Add.

8.	From the Protocols list, select the desired protocols to run over this adapter, then select Add.

9.	Select OK to accept the configuration. All editing is complete.

10.	The Configure panel reappears. Select Close.

11.	In the Multi-Protocol Transport Services panel, select Exit.

12.	In the Update CONFIG.SYS panel, ensure that the Update CONFIG.SYS box is checked, and select Exit.

13.	When the CONFIG.SYS Updated information panel is displayed, select OK.

14.	In the Exit MPTS panel, instructions are given for making the configuration active. Make note of the instructions so that you can follow them later, then select Exit.

15.	After you have followed the Exit instructions, the ATM Adapter device driver installation is complete.

Installation under Novell NetWare
Installing ATM device drivers under Novell NetWare requires modifications to the STARTUP.NCF and AUTOEXEC.NCF files. The Novell INSTALL program automatically configures and installs LAN-based communications adapters and protocols for Novell NetWare environments. You have the option of manually installing device drivers, but the task can be tedious, so use NetWare INSTALL whenever possible. (Some adapters provide an installation program that installs the device drivers independent of NetWare INSTALL.)

ATM adapters do not appear in the NetWare default list of adapters. Follow these steps to add the ATM adapter and desired protocols under NetWare using Novell's INSTALL program. Note: Prior to the installation, you may be required to manually update the STARTUP.NCF file to increase buffers or receive packet sizes. Consult the manual provided with your adapter.

1.	To start the NetWare installation program, type LOAD INSTALL and press Enter.

2.	In the Installation options panel, select Driver options.

3.	In the Driver options panel, select Configure network drivers. The Additional driver actions panel appears.

4.	In the Additional driver actions panel, select a driver.

5.	Insert the diskette containing the NetWare device drivers for the ATM adapter that is installed in the PC Server.

6.	Press the Insert key to install a new driver from the diskette in the diskette drive.

7.	Press Enter to start the search on the diskette.

8.	When the Select a driver to install panel reappears with a new window listing the driver that can be installed, select the driver for the ATM adapter you have installed, then press Enter.

9.	You are asked whether or not you want to copy the driver. Respond with Yes.

10.	Once all the drivers are copied, you may see more panels for configuring the adapter, depending upon the adapter BUS and the vendor implementation. In most cases, you specify the slot where the adapter is installed and its locally administered address.

11.	After you have completed the installation and configuration, exit the installation program.

12.	Check the AUTOEXEC.NCF file to verify that the installation program added LOAD statement(s) for the adapter drivers and BIND statement(s) for the protocols. If not, add them as described in the manuals provided with the adapter.

13.	Shut down and restart the server.

Installation under Windows NT
Installing ATM device drivers under Windows NT is supported only through the Network program in the Control Panel. This means that the diskette containing the ATM adapter drivers for Windows NT must also have an OEMSETUP.INF file.

ATM adapters do not appear in the Windows NT Network Installation Program's default list of adapters. Follow these steps to add the ATM adapter and desired protocols under Windows NT using the Network Installation Program.

1.	Log on to Windows NT as an administrator.

2.	In the Control panel, execute the Network program.

3.	In the Network Settings panel, select "Add adapter."

4.	In the Add Network Adapter panel, select " requires....", then select Continue.

5.	When the Insert Disk dialog box appears, insert the ATM adapter's Windows NT driver diskette for the adapter you have installed, then select OK.

6.	When the Select OEM Option dialog box appears, select the ATM adapter that you have installed, then select OK.

7.	Depending upon which adapter you installed, you are presented with a series of panels in which you configure the ATM adapter. Follow instructions in the panels to finish installing the adapter.

8.	Once you have completed the adapter installation, the Network Settings panel is displayed again. Select "Add software" to install the LAN emulation software provided with the ATM adapter.

9.	In Add Software panel, select " requires....", then select Continue.

10.	When the Insert Disk dialog box appears, insert the ATM adapter's LAN emulation software diskette for the adapter you have installed, and select OK.

11.	When the Select OEM Option dialog box appears, select the LAN emulation software for the ATM adapter that you have installed, then select OK.

12.	Once the software is copied, follow the instructions in the subsequent panel to configure the software. Once the configuration is complete, save all changes.

13.	To make the configuration active, restart the system.

General Installation Considerations
Regardless of the NOS installed on the PC Server, you should complete some basic steps prior to adding any communication adapter or driver:


 * Upgrade the BIOS to the latest level available.
 * On split BUS MCA/PCI servers, load the PFEE7.ADF file that corresponds to your installed communication adapters' BUS architecture.

IBM ATM Adapters for IBM PC Servers
Figure 5 lists the ATM adapters offered by IBM that conform to the Micro Channel, ISA, and PCI BUS architectures and support the NOSs that run on the IBM PC Servers.

Figure 5