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The mighty LAN: Local area networking at Penn

By BIll Rawles

A host of sophisticated computational, analytic, forecasting, text processing, and communication tools are commonplace on individual computers and workstations at Penn. Members of departments and work groups, however, increasingly need to work collaboratively, so finding ways to manage computer systems and information to achieve successful collaboration has been a challenge for many University offices. Setting up a local area network, or LAN, which links computers to shared peripheral devices, such as file servers, printers, and modems, is one solution that provides for effective collaboration.

To encourage a standard networking environment at the University, the Office of Information Systems and Computing (ISC), in January 1992, selected Novell Netware as the recommended software for DOS-based LANs. It joins AppleTalk, the de facto standard for Macintosh networks.

What is a LAN?

LANs can be either peer-to-peer or client/server in design. In the peer-to-peer model, all the attached computers are equals, and each controls access to its hard disk drive, files, printer, and other attached devices. In the client/server model, one computer functions as the server (often called the file server because it stores the shared files), and the other computers are its clients. Files, disk drives, printers, and other peripheral devices are attached to, or reside on, the server, and the server controls access to these files and devices. Larger LANs may have more than one server and may also have specialized servers, such as a print server dedicated to printing.

Both AppleTalk and Netware provide LAN communication and will work over either coax or twisted pair copper wire. An AppleTalk network is basically peer-to-peer in design but also supports a client/server structure when AppleShare software is installed on a server computer. A Netware network is a client/server implementation.

Some LANs at Penn

The Penn Admissions Office has a LAN of medium complexity. It includes more than one type of computer, and users access data from the University's central administrative computer. The network uses Novell Netware, and has a file server for sharing applications and both DOS- based machines (IBM PC/compatibles) and Macintoshes as clients. This LAN has enhanced the Admissions Office's ability to provide timely communications to candidates for admission to Penn.

Dining Services has one of the more complex LANs at Penn, with multiple file servers and client machines distributed all over campus. The information necessary to provide meals to thousands of students has to cross PennNet routers, infrastructure elements that add to the complexity. In addition, the control of card key access to buildings is dependent on this network.

Advantages of LANs

Data sharing. People working in groups often share tasks. For example, several people may write different parts of a proposal. In a stand-alone environment, sharing the data is inefficient-disks need to be passed around and copied-and eventually version control problems develop. In a LAN environment, each person can be given access to a single file on a server that contains the entire proposal. Individuals can work on different parts of the proposal simultaneously, without having to make copies or worry about which version is most current. There is only one version.

Printer sharing. Buying a printer for every computer in an office is very expensive. But not having a printer attached to each computer is inefficient-some people need to copy data to diskettes, take them to a computer with a printer attached, and, if necessary, wait for the computer to be free. LANs allow two or more computers to share a printer without the extra steps.

Software compatibility. Collaborative work is hampered when members of a work group use different versions of the same software. Installing network versions of popular applications, which more than one user can access simultaneously, eliminates the problem of version incompatibility.

Software cost. Buying and maintaining current versions of software for individual machines (necessary to meet vendors' copyright requirements, as well as for compatibility) stretches the budgets of many offices. Though a network version of an application costs more than a single-user version, in the long run it's cheaper than purchasing many individual copies.

Maintenance and troubleshooting. Computer systems require maintenance, including such tasks as installing software updates, replacing printer ribbons or cartridges, and minor troubleshooting. Many users see this as a distraction and avoid it, sometimes at their peril. In a LAN environment, these tasks are done centrally.

Backups. Backing up data, even critical data, is the activity users neglect most often. Given the time and effort required to create data, its loss is an expensive setback for any organization. In a LAN environment, critical shared data stored on the server is backed up centrally. Some LAN products now have the capability of backing up individual hard drives from the server as well.

Local commitments required

Implementing and maintaining a LAN is much more complex than maintaining stand-alone computers. Organizations considering a LAN must keep in mind that they will need someone with computing skills on staff whose primary job will be the care and feeding of the LAN.

Security becomes a bigger issue when many computers are connected together and there is wide access to a server, particularly if dial-in access from home is available. Careful planning and structuring of appropriate security procedures reduces the possibility of problems in this area.

Network failure and inability to access the server for extended periods of time results in lost productivity and other problems for a whole group rather than an individual. It is important to have a hardware maintenance contract that guarantees quick response and repair when a work group's productivity is heavily dependent on a LAN.

Macintosh and DOS-based LANs

DOS-based PCs were not designed with networking in mind and, consequently, are much more difficult to network. There are many different networking products on the market for DOS-based machines, many of which the ISC considered before deciding to support Netware. Netware is an operating system itself and only requires DOS for booting. It then provides all the communications and device management capabilities required in a robust LAN environment.

Does your office need a LAN?

Connectivity should drive your decision. The primary factors you should consider are what equipment in your office needs to be connected together and what equipment and services outside your office you need to connect to.

AppleTalk or Netware?

As was mentioned earlier, AppleTalk is much easier to implement, manage, and use than Netware. It is the product of choice if most of the machines you want to connect are Macintoshes and your primary requirements are sharing text and spreadsheet information. AppleTalk is not good for complex database applications because it is relatively slow. In addition, its security features are not very substantial.

Netware is a fast, high-powered network operating system, best used in a primarily DOS-based environment where database applications and communications speed are important. Netware (version 3.11 in particular) has excellent security features and is the best choice for applications that require high levels of security. Maintaining Netware properly requires substantial computing skills. If you have applications that appear to be best served by using Netware, but most of your computers are Macintoshes, don't be concerned. In the latest version of Netware, Macintosh connectivity is implemented so that users will access the Netware server as if it were an Apple server and won't be aware of the additional complexity of a Netware LAN.

PennNet & Internet connectivity

PennNet, the campus's primary data communications network, provides this broader communications capability and the associated services that are not available with only a LAN. LANs attached to PennNet can take advantage of these services using specialized hardware, such as gateways and bridges, or sometimes only additional software.

Remote access

Using products that take advantage of SLIP (Serial Line Internet Protocol) technology, you can dial in to PennNet over phone lines and function as though your computer at home had a direct high-speed ethernet connection to PennNet. (See Penn Printout, November 1992, page 8, for information on SLIP.) You can then use client/server applications such as POP mail, do file transfers using FTP, or access data directly on your office machine or LAN server. Using ARAP (Apple Remote Access Protocol), you can dial in to your AppleTalk network and do anything from your home Macintosh that you can do on the Macintosh in your office. As technological developments are implemented in new products, enhancements to remote access will continue to be provided to the Penn community.

LAN services available

• Data Communications and Computing Services (DCCS) provides campus- wide coordination of all network services. This includes providing the guidelines for, and, when necessary, assistance in, connecting LANs to PennNet.

• DCCS coordinates and facilitates two LAN administrator groups on campus: the Mac Networking Group for Macintosh LAN administrators and the Novell System Managers Group for Netware administrators. These groups provide peer-to-peer support, a forum for discussing network interoperability issues, and a formal access point to ISC network management.

• The ISC provides a number of site licenses and volume purchase agreements for software for LANs on campus. For example, there is a site license for Apple's MacTCP software and a volume purchase agreement for Novell's LAN WorkPlace for DOS software.

• DCCS provides consulting in areas such as LAN need assessment, identification of alternatives, configuration, and cost.

• The ISC will function as a broker for outsourcing any networking service that an organization doesn't have the internal resources to provide for itself, such as initial implementation of a network. A report is currently being prepared on the six network services vendors who responded to the ISC's Request for Information.

• If there is sufficient demand to warrant providing a central network server for use by departments or work groups that aren't large enough to pay the total cost of implementing and supporting a LAN, the ISC will provide a central server service for a charge.