50-10-30 Multiple Protocols: The Network Manager's Previous screen Headache Joe Pruskowski Payoff Many IS professionals face the task of managing complex networks. This article discusses methods of connectivity, including multistacking and the use of software-based gateway technology, in an effort to help managers effectively deal with multiple protocols in the LAN environment. Problems Addressed Rightsizing is a goal of many CIOs today. The basic method to attain true rightsizing is to move information closer to the individual workers within the organization, especially through client/server computing. By their very nature, networks are the logical structure to make this happen. Many corporations have a mix of both departmental and corporate LAN systems combined with legacy systems, all with disparate methods of communicating in a network. Today's networks are very open, but often very chaotic. Managing such complex networks has become a real challenge for network managers. For connectivity, IS managers often rely on one of two common methods: stacking multiple protocols, or “multistacking,” and using gateway technology. For IS managers facing integration decisions, information on all of the options is critical. LAN Client Support The dominant LAN Network operating system is NetWare, and therefore the standard for LAN protocols is IPX/SPX. Parallel to the LAN , legacy systems are still using their proprietary protocols to support access to mission-critical applications and data. Typically IBM's System Network Architecture, DEC's Local Area Transport and DECnet, together with a variety of applications running on TCP/IP, have become the most prominent protocols running on the host. Exhibit 1 shows the interactions between clients and hosts within the network.
Client and Host Interactions Because the networks in most organizations are made up of a variety of protocols, users in various places on the network cannot access the resources they need. A company attempting to solve this problem must deal with some significant issues:
á Initial setup cost, including purchase and installation cost, for each workstation on the network.
á Ongoing administrative support costs, which include the purchase and installation of software upgrades and the maintenance of network address management. Each protocol stack has a different naming scheme. For example, a LAT host name is a simple test string (e.g., SYSTEM1), where a TCP/IP node name is tree-structured dot notation (e.g., SYSTEM1.NORTHWEST.ICXN.COM). á The limited number of applications supported by any one protocol. Previous screen á The burden on the infrastructure when there are too many protocols to support efficiently. This burden is realized by the network hardware, which now must deal with managing multiple protocols. Support personnel must also know how to deal with these protocols.
á The high administrative costs in large, heterogeneous networks. This is a serious problem because the costs continue to climb. What IS Multistacking? Multistacking means that every LAN client would have to run all other legacy protocols (e.g., System Network Architecture, Local Area Transport, and DECnet)in addition to its native protocol (e.g., Internetwork Packet eXchange) to gain access to all corporate data. The number of LAN clients that must run multiple protocol stacks in most major corporations is very large—typically measured in the thousands. While in theory multistacking will solve the problem, it comes with an entire set of its own problems, multiplied by the sheer number of LAN clients that are affected. Some of the major problems that must be dealt with on each DOS/Windows system are:
á Conflicts in memory usage, since many stacks still run in real-mode.
á Conflicts in Terminate and Stay Resident (terminate and stay resident) programs.
á Conflicts in network address spaces (i.e., differing address schemes).
á Use of network device drivers by multiple protocol stacks, which require complicated setup procedures. Connectivity Alternatives to Multistacking There are a number of solutions available today that minimize protocol stack propagation, each with its advantages and disadvantages. Proprietary Vendor-Specific Suites These are typically sold by the major computer vendors. Examples would be Pathworks from Digital Equipment Corp. and IBM's LAN Server products. These usually provide a high level of functionality, but are mainly account control mechanisms and can be cumbersome to use. In addition, they are usually expensive because license has to be purchased for every user on the network. Standardization on One Protocol Stack In an ideal world, this would be Open Systems Interconnection, though TCP/IP seems to be filling this role as a practical solution. However, although TCP/IP is found on the backbones of many corporations, it rarely makes it to the client. TCP/IP can be cumbersome to install on a large number of nodes, but it does provide an excellent “intermediate” protocol. Because TCP/IP can support a wide variety of equipment, there are many parameters that must be set up on each TCP/IP system, not the least of which is the node number, which has to be assigned for each node. This approach can also be expensive, as it is purchase on a per-node basis. The Software Gateway Previous screen Another alternative to multistacking is the use of gateway technology. Gateway technology was first introduced as rather expensive hardware. A single vendor had to install and maintain the gateway, typically at a very high cost to the user. New gateway technology is software-only and can be run on virtually any commodity hardware platform. An early example is Novell's NetWare for Systems Application Architecture, which connects LAN clients to IBM mainframes. Another is InterConnections' Leverage Gateway Services, which is based on Novell's NetWare for Local Area Transport technology and connects Digital Equipment Corporation systems with NetWare clients. The gateway technology emerging today serves as a true gateway-- one type of protocol is actually converted to a different protocol type. An example of this would be an inbound terminal session over NetWare Internetwork Packet eXchange that is converted at the gateway to an outbound LAT terminal session. There are several advantages to this new type of gateway:
á It can reside on any Intel 386/486/Pentium hardware platform and provides protocol translation between the LAN client and host environments.
á It is ultimately manageable using the industry-standard Simple Network Management Protocol protocol. The management capabilities are based on the translation tables that are inherent within the gateway. This allows for “logical network management” of network resources, building on the physical management capabilities that are currently being deployed by a wide variety of vendors. Logical network management brings meaningful information to the network manager, such as the number of sessions in use and the number of files transferred.
á Concurrent user licensing is cost-effective. Any supported host can be accessed by the LAN clients. The user company does not have to license each host to allow access from its client systems.
á Concurrent host usage is cost-effective. Any supported host can be accessed by the LAN clients. The user company does not have to license each host to allow access from its client systems.
á The number of protocol stacks on the LAN client and host are greatly reduced.
á There is no need for additional kernel-mode protocol stacks on the host machines. By applying software gateway technology to the multiple protocol situation, IS professionals have a new set of tools that can help them achieve their goals. A Sample Case The next section examines the system at a major airline reservation center. The center has a large collection of NetWare LANs with thousands of IPX/SPX clients. In addition, there are dozens of hosts that are a combination of Digital Equipment Corporation and UNIX systems. These systems are all physically connected, but use very different network protocols to communicate. The LAN clients mainly use Internetwork Packet eXchange, the UNIX systems use TCP/IP, while the DEC systems use a combination of Local Area Transport and DECnet. Personnel at the center take reservations over the phone using a reservation system Previous screen that runs on UNIX and is connected via TCP/IP. From the same desktop system, they also perform outbound telemarketing (e.g., making customers aware of an upcoming new frequent flyer program) and must access a VAX/VMS system for lead information via the LAT protocol. In terms of connectivity, the company could:
á Install all protocol stacks (i.e., Internetwork Packet eXchange, Transmission Control Protocol, LAT) at each client. Installing all these protocol stacks at each client would add wear and tear on the network management personnel alone. The stacks have to be loaded and configured on each client and, over time, must be maintained. There is also a charge for each stack-per-client.
á Install a TCP/IP stack on all hosts and clients. In most cases this does not support all of the applications required, so it becomes restrictive and might require at least an IPX stack to be coresident. Although the network management personnel have fewer stacks to worry about, they still have to configure and manage two stacks at each client.
á Install gateways at the edges of the LAN infrastructure to the host systems. This saves network management personnel wear and tear because the protocol translation gateway is installed at a central point. There are fewer stacks to worry about, and by simply leaving Internetwork Packet eXchange on the LAN clients, the LAN becomes easy to manage on an ongoing basis. Cost is also minimized because money is saved on protocol stacks and their subsequent maintenance. In the future, more companies will implement strategic protocols such as IPX and TCP/IP across their network backbone while applying software gateway technology to bring legacy systems into the network. Exhibit 2 illustrates the effect of applying gateway technology to simplify the overall network and provide basic functionality for all legacy systems.
Applying Gateway Technology
Recommended Course of Action An optimum plan for managing a multiprotocol environment must achieve certain goals. The minimum set of requirements are:
á Minimize the number of protocol stacks at the client.
á Minimize the number of protocol stacks at the host.
á Support a variety of critical applications, such as terminal service, file transfer, and printing.
á Take a “network-centric” viewpoint.
á Provide logical network management of these services. With the emergence of software gateways that run on commodity hardware, it has become cost-effective to provide a high level of connectivity and manageability while allowing network managers to contain their costs. Author Biographies Previous screen Joe Pruskowski Joseph J. Pruskowski is the vice-president and chief technical officer of InterConnections, Inc. in Bellevue WA. He is one of the original cofounders and has been with the company since 1987. Previously, he managed an engineering group at ESCA Corp. He was also a communications systems programmer with Sandia National Labs and Digital Equipment Corp. He holds a BS degree in computer science from the University of New Mexico.