Multi-protocol LAN Design & Implementation: A Case Study
DR. SUNIL HAZARI, Assistant Professor East Carolina University Greenville, N.C. Local area networks have surged in popularity. With the myriad hardware, software, and network operating system options available, it becomes necessary to carefully plan a network before installation. This article is a case study in design, implementation and budgeting issues that were considered while installing a multi-protocol local area network. A glossary of common networking terms is also included. The School of Industry and Technology at East Carolina University offers a Bachelor's of Science degree program in Industrial Technology with concentrations in Manufacturing, Electronics, Industrial Distribution, Engineering Design/Drafting, and Construction Management. About 600 students are enrolled in these programs and another 70 are enrolled in the Masters' of Science program in Industrial Technology and Safety. The school has demonstrated a commitment to establishing a premier program of study focusing on preparation of managers and decision-makers. Over the past five years computers had been regularly installed to support instruction. All labs and department offices within the school had their own workstations and peripherals. With a critical need to exchange data, share expensive resources such as plotters and printers, and communicate using electronic mail, it was only a matter of time before the need for a LAN was identified. It was determined that the network would help support the school's long-term goals as outlined in the Strategic Plan, which emphasized distinction in undergraduate education, plus excellence in teaching, research and creative activity. Priorities for Action in the plan called for integrating information technology in courses to improve learning. Designing the Network With a variety of hardware and operating systems being used, the proposed network had to support multiple protocols to connect the approximately 100 nodes in the School of Industry and Technology. The goal was to design a network that would provide connectivity not only within the school, but also to university mainframes, minis and other computing resources. A preliminary needs assessment was conducted. Factors affecting purchasing decisions were initial cost, multi-protocol support, compatibility with existing applications, upgradeability, products' installed base, vendor support, training, overhead and maintenance costs. Network operating systems from various vendors were considered. Since Novell NetWare offered a 32-bit network operating system with features such as security, remote management, multi-platform support (for DOS, Windows, Macintosh, UNIX and OS/2), relative ease of installation compared with other products in its class, and support for up to 250 users, it was selected as the network operating system. Several other departments in the university had previously installed NetWare-based LANs and reported positive experiences. These sites were internal resources that could be tapped for on- going support during installation and for troubleshooting. A server, network operating system, network interface card (NIC) and cables were purchased. When the server was first installed, a small number of computers were connected together using Token Ring topology. It was considered important to start small and work in a controlled environment to make troubleshooting easier. User accounts were set up for the system administrator, selected faculty and lab staff. Following system configuration for application software access, the network was put in use for the ITEC 2000: Industrial Technology Applications of Computer Systems class, which is taught in the computer lab. A custom menu environment provided students with transparent access to the network without requiring them to learn cryptic commands at this stage. Lab assistants were given access to printer console applications to help maintain print queues. First Steps: Labs and E-Mail Software Initial plans called for networking only the IBM laboratory on the first floor of Rawl Building (see Figure 1). Following successful implementation, the Macintosh laboratory, faculty and staff offices on the same floor were added in the second phase. After purchasing hubs and additional cables, offices on the third floor were also connected to the network. Token Ring, 10BaseT and LocalTalk cables were used for connecting nodes to the server. The third phase involved connecting department labs, staff and faculty offices located in Flanagan building. Because of the distance between the two buildings (500 ft.), fiber optic cable was used to connect the two LAN segments. At this time, most network use comprised running software applications from the server. Other than fine tuning network configuration files and learning system administration tasks pertaining to creating new accounts, performing backups, setting rights and creating groups, the network was operating without major problems. The next significant step was to offer electronic mail and Internet access from each node on the network. After reviewing various commercial, freeware and shareware e-mail software packages, Pegasus Mail (PMail) was chosen for the network. The main reason PMail was selected over other e-mail packages is that it has clients for DOS, Windows and Macintosh platforms. Other features offered by PMail include a friendly interface, password protection, file attachments, confirmation of message delivery and reading, support for MIME (Multipurpose Internet Mail Extension), address books and mailing list capabilities. Pegasus Mail requires a NetWare server to operate and, in addition to local mail, it also supports Internet mail by using an e-mail gateway running on the server itself or via a DOS-based gateway running on a separate machine. PMail was developed by David Harris of New Zealand and is available at no charge. Using ftp, PMail can be obtained from risc.ua.edu in the directory /pub/network/pegasus. Harris sells licenses to make unlimited copies of the manual, provides technical support over the Internet and, due to a large installed user base, feedback to any problem is usually quick. Internet Connectivity The Internet is a gold mine of information for students and educators. A simple method of providing Internet access from any node on the school's LAN would have been for the node to connect to our campus' broadband backbone, which supports IPX/SPX, TCP/IP, Ethernet, AppleTalk, and DECNet protocols. A terminal emulator could then be used to access the university's VAX or IBM ES/9000 computers already on the Internet. Although workable, this type of access would not allow students and faculty to utilize newly developed client/server programs that boast a graphical interface to make information access easier. To overcome this problem, a direct IP connection from the LAN to the Internet was needed. This is possible by using a router and TCP/IP support software. Novell NetWare Multiprotocol Router was selected for this task since it was a low cost, software-only solution. A combination of interfaces and protocols including Ethernet, Fiber Distributed Data Interface (FDDI), AppleTalk, Token Ring, IPX and TCP/IP is also supported by the Multiprotocol Router. To retrofit the LAN to access Internet directly, the router was configured to forward IP datagrams to and from the university backbone. An IP network number was assigned to the router port. LAN WorkPlace for DOS and MacTCP for Macintosh client software were then installed on respective network nodes. This gave each workstation the ability to use ftp, telnet, gopher and WWW client software in a pull-down menu, icon and window-based graphical environment. Remote access to the LAN was also made available to school faculty by using Norton PC Anywhere (DOS) and Apple Remote Access (Mac) client software. Due to security concerns and the availability of only one phone line, access via remote dial-in is restricted to use of e-mail and login to university mainframe computers. LAN Expenses A typical LAN installation usually requires large investments in hardware, software and staff training. This may be difficult to justify (especially in academia) since the benefits cannot be directly quantified in dollars. Assuming that individual computers have already been purchased, each computer has to be equipped with a network interface card (NIC). Other purchases will be required as well, such as a network operating system, a dedicated server with multi-protocol NICs, cables, hubs, bridges, routers, tape drives, modems, UPSs for protection, networkable CD-ROM drives, analyzers, and network versions of application software. Figure 2 shows an itemized list of expenses incurred for the LAN. Prices are for reference only since they reflect educational discounts, bulk purchases, special orders and more. (Note that individual PCs, printers, plotters, etc. are not included.) Recommendations There were many lessons learned after the network was installed. Things that looked fine on paper did not necessarily work or had to be reworked or replaced after installation. Below are some recommendations to help minimize logistic and technical problems pertaining to network installation. Plan the network Effective integration of a LAN into an organization requires careful planning. Purpose for a LAN, the topology, protocols, number of nodes, support and training are some of the factors that directly impact a LAN design. In addition to meeting short-term needs, all networks should be designed for future growth by being upgradeable to accommodate applications that will demand a higher bandwidth. If current trends continue, two common examples of such applications in educational settings are multimedia and desktop video. A high initial cost is the main factor deterring LAN installation in many colleges. In many cases, the expenses shown in Figure 2 may exceed the entire year's budget for information technology. In such situations, consider an incremental installation, with additional network segments being added as funds become available. Cable drops Most networks start small and then grow rapidly as additional nodes are added. Our school's network, for instance, was initially designed to connect a few offices and a lab, but in the span of just one year, expanded to include other labs, staff and faculty offices distributed between two buildings. Due to this unforeseen growth, new cable runs had to be made for each segment added. In hindsight, drops should have been made in each office (occupied or not); it would have been much easier to then connect nodes to the network. Use high-quality cables A majority of network problems occur as a result of incorrect choice of cable type or improper connector installation. Cable choices range from existing twisted pair phone cable to unshielded twisted pair (10BaseT), data-grade twisted pair, coaxial (Ethernet) or fiber optic. Each type has advantages and disadvantages in terms of cost, speed, distance and susceptibility to interference. These factors should be fully explored during the planning stage. Installation should be done by data communication cablers rather than ordinary electricians since the latter may not be aware of building codes and other factors that govern data-grade cables. Provided they are installed correctly, cables have a longer life span than the equipment they connect and as a result only the highest quality connectors and cables should be used. Use LAN analyzers As the number of nodes on a LAN increases, it becomes difficult to track down hardware or software incompatibilities that may be causing data bottlenecks or other glitches. LAN analyzers are hardware and software devices used to pinpoint the exact cause of network problems -- in the cables, connectors, NICs, software or node hardware. Analysis tools range from multimeters and time-domain reflectometers that test for cable shorts, to protocol analyzers that go beyond the cable level to actually check for protocol problems. Built-in features of some LAN analyzers include filtering capability, traffic-pattern generation and analysis, statistics, and protocol interpretation. This offers the convenience of identifying problems from a remote site or even a central-access location. Because of their advantages in terms of reducing downtime by aiding network troubleshooting, LAN analyzers should today be considered a required tool in the network administrator's arsenal. Administration and training Administration and maintenance of a multi-protocol network needs the specialized skills of a full-time network administrator who is familiar with various hardware, software, protocols and configurations. This person is mainly responsible for performing backups, handling upgrades and maintaining data security. In addition to technical skills, the network administrator must also have interpersonal skills to train staff and users on the operation of devices on the networks. Changes to network topology, hardware and software must be documented and maintained on a continual basis. This becomes even more important if there is only one network administrator. Since staff turnover in academic computing is high (because of the salary differences between academia and industry), it is recommended that an interested faculty member be given shared responsibility of network administration. This also helps in cases where the full-time network administrator is temporarily unavailable or if he or she decides to leave. In addition to serving as "tech backup," a faculty member looks at a network from a different perspective -- viewing it not as a technical end, but as a means to an instructional end. Networks can be used for creative applications such as e-mail use by students, electronic delivery of class exercises, grade retrieval, and group assignments that promote collaborative learning. These experiences may be shared in training sessions and workshops offered to other faculty interested in using the network as a tool to enhance teaching and learning. The author would like to thank Stuart Rosner, school technician, for his assistance in providing protocol specifications for this article. Sunil Hazari is a faculty member and Director of Computer Facilities in the School of Industry and Technology at East Carolina University. He has presented papers at conferences, written articles and conducted faculty-development workshops in computer applications, multimedia, networking and information technology. E-Mail:
[email protected]