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Local Area Network

By Marketing Research Team, 3EA
Local Area Network

In a LAN, each PC has a LAN adapter card for connecting to the medium. These logic cards cost anywhere from approximately Rs.3, 000 to well over Rs.10, 000. However, like the cost of many electronics components, the cost of these boards is coming down. The benefit gained from high performance LAN's is higher speeds. At the low end, these systems provide transfer rates over 10 Mbps, as fast as or faster than locally connected floppy disk drives. At the upper end of the scale, data speeds exceed 1000 Mbps. The industry trend is toward increasingly higher speeds.

Some of the LAN options, particularly a high speed LAN with a powerful file server, are beyond Pinnacle's budget. However, there is a wide variety of LAN options that are within Pinnacle's budget and that will satisfy Pinnacle's needs. One major advantage of a LAN solution is transparency. All file and printer sharing is done almost as though the files and printers were locally attached to the user's PC.

Peer to Peer (P2P) Local Area Network

P2P provide a subset of LAN capabilities. They allow peripheral sharing and file transfer capabilities without the need for a dedicated file-server. The cost of P2P LAN is lower but performance is lower too. In addition, the security of data is much lesser than a server based LAN. Each user can assign share rights to his files. The sharing can be "read only" or "read & write". All users use a common password to access the files.

The disadvantage of a P2P LAN is that a user of a PC can only assign one level of access rights to all the users. In addition, the user PC must be powered on for others to be able to access the files. User PC is slowed down when others access files from it. This is because user PC has to do additional work of resolving other users file access or print requests besides doing the work of the user himself.

Contention can also occur. If, for example, Rita D'Souza and Mahesh Arora both wanted to connect to a specific laser printer connected to a specific user PC, only one of the connections can be made. If D'souza request were received first, Arora would need to wait until D'Souza's print jobs were completed. Only then can his connection request be granted.

SERVICE BUREAU ALTERNATIVE

Another alternative Kochar might consider is contracting with an external data processing service. Data will be stored at service bureau's computer. Pinnacle will be able to use its existing computers and terminals to connect to operate in a stand-alone mode when not connected to the service bureau's system.

Under the Windows 3.11 operating system, it is not possible for a PC to operate in both modes simultaneously. However, with a multitasking operating system like Windows 95 even that is possible. That is, under Pinnacle's current operating system, when connected to the service bureau system, the PC can operate only in terminal emulation mode. In that mode, it can run programs on the host and transfer files to or from its local disk. It is not able to run local programs such as word processing or in stand-alone mode; it is not possible to access the host to transfer files. With a multitasking Windows95 operating system, local applications can run concurrently with host access. Connection to the host might be made via the computer's serial port to a statistical multiplexer.

This will allow each PC to access to the host at any time while minimizing line costs.

On the negative side, this solution does not provide some of the capabilities Pinnacle needs. First, although data files can be easily shared, program files pose a problem. Downloading programs from the host over a typical communications link of 9, 600 bps will be quite slow. At that speed, a 250, 000byte program will take a minimum of 4.3 minutes. That figure assumes 100% line utilization for data, an unrealistic assumption. Thus, the link is most useful only for exchanging rather small data files. Program files will still need to either reside locally on each system or be programs that run on the host. For example, the client database could be maintained entirely on the host using the host's database management system and host resident programs. Naturally, the more the resources of the host are used, the greater the cost to Pinnacle. Gupta summarized the options available to Kochar.

IMPLEMENTATION CONCERNS

Management of a LAN, even a small one like the one Pinnacle might implement, is time consuming. One of the biggest changes between a LAN and several stand-alone systems is that someone needs to be responsible for the LAN. That is, to provide efficient, continuous service, there ought to be a LAN manager/operator. Although this is not a full time function for a small LAN, it does take extra time and expertise. For a large LAN, the system management tasks can be a full-time job. Converting to a shared system carries with it an entirely new set of responsibilities.

LAN MANAGEMENT RESPONSIBLITIES

System administration-
Since a LAN requires shared devices such as printers, printer controllers, and one or more servers, someone must be responsible for caring for them. Files on the server need to be backed up periodically. If the disk becomes full, someone must be responsible for removing or archiving files. New files and programs must occasionally be added to the system. Individual user directories need to be created. Security measures must be imposed. Batch files need to be created to provide a variety of functions such as user login, search paths, and so on. At Pinnacle, there are several unanswered questions such as:

  1. Who will be responsible for assigning file and user security?
  2. Who will install new version of the file server's operating system?
  3. Who will be responsible for upgrading the LAN software on
  4. Each individual system?
  5. Who will connect new systems and LAN devices?
  6. Who will report problems to the vendors?

Although the LAN office assistant does not need to be a computer expert, he or she must at least be super user and have an aptitude for technical details. Gupta indicated that if the LAN office assistant came from Pinnacle's current staff, Kochar will likely have to send him or her through several weeks of training.

Training-
The LAN manager needs to know enough about the system to add new users, install operating systems, gather information regarding problems, and even solve problems of a local nature. None of Pinnacle's current employees has the necessary expertise to fulfil the role of LAN manager. Gupta also indicated that it will be prudent to have at least two people capable of performing such functions. With two people, it will be more likely that at least one person is available when problems occur. Moreover, Gupta indicated that the users will also need some additional training. For instance, they will need to know how to route their print outputs to the proper printer and how to log on to the system. Although for the most part, users will use the system in much the same way as before, using it will not be completely transparent. Some of the solutions, like a P2P LAN, require completely new operating procedures. A few hours of education for each employee will be necessary.

Maintenance-
Pinnacle does not carry a maintenance contract on any of its equipment. If a printer or computer breaks, it is taken to a local computer store for repair. Sometimes, the repair might take a week, but the loss of one PC or printer for that amount of time is not too disruptive. However, if the file server fails and is out of service for a week, what would the effect be on Pinnacle's business? Each of the PCs could, of course, continue operating in a stand-alone mode. However, the files and programs on the file server will not be available. The printers will be available only if reconnected directly to an individual PC.

If the system fails, someone must gather the problem details and either fix the problem or call someone to make the repairs. Even if the file server never has a problem, there are numerous small maintenance and operations tasks which must be done-charging ribbons and toner cartridges, keeping a stock of paper, maintaining the copies of the disk backups, keeping software and documentation current, interfacing with suppliers, and so on. Under the current mode of operation, each of these responsibilities are disturbed among all the employees.

Because of the critical nature of shared hardware like a LAN server or hub, Gupta suggested that Pinnacle consider placing that equipment under a maintenance agreement. This was a recurring cost Kochar had not counted on.

Software-
All the software Pinnacle had acquired were stand-alone versions. In all cases, the software vendors had network versions available. All of Pinnacle's software vendors allowed their customers to upgrade stand-alone versions for a network licensed version. Usually the software vendors levied a modest charge for the upgrade and corresponding documentation.

Pinnacle was fortunate in this regard. Some software vendors do not have an upgrade policy. Their customers must purchase a completely new network version of the software without receiving credit for the software they have already purchased.

Once received, the software needs to be installed, individual or corporate configurations established, and then the software installation tested to ensure that it operates correctly. Even if doing all of the above is not complex, it does tend to be time consuming.

Communications Speed-
Kochar needs to decide how the computer solution will be used immediately and predict how it will likely be used in the future. These characteristics help determine the correct alternative and associated communications speed. Some solutions to the immediate problem may be unsatisfactory for future needs. If system use will be primarily to access records and small word processing documents, then a lower speed between the server and PCs will be adequate. If large programs are to be downloaded from a shared disk, then higher speeds are essential. If several new users are likely to be added or if the existing users will be frequently accessing a shared disk concurrently, then the speed of the communications link should be relatively high.

LAN alternatives

When Gupta explained the LAN alternatives, he began by saying that perhaps the biggest problem Kochar will face with a LAN solution is selecting one system from the number of alternatives. The possibilities range over a wide spectrum of serves and networking schemes.

If Kochar choose this solution, her objective must be to select an option that is cost effective and capable of a certain amount of future expansion while providing sufficient performance.

All LAN implementations, at the minimum, require an investment in software and cables. Many require additional hardware as well. Gupta briefly explained to Kochar how a LAN would work at Pinnacle. To show Kochar how a LAN will meet her needs, Gupta drew a possible configuration for Pinnacle. His drawing is showing in figure below.

If Pinnacle implements a LAN, each of its PC's will be connected by some kind of wiring to central hub. For a LAN the size Pinnacle is contemplating, the most likely medium is twisted wire pairs. The wires might be installed specifically for the LAN, but it is possible that the existing telephone wire will work.

LANs can be categorized in several ways. One way is with respect to how devices are shared. Some LANs, particularly the high speed ones, require a dedicated server. The server is a computer that receives requests for file and or printer services and acts on those requests. A dedicated server performs no other functions. That is, a dedicated server cannot also function as user's PC. Other implementations allow one or more user PCs on the network to also fulfil the functions of a server. This implementation is more commonly found in low speed LANs.

Regardless of which of the above approaches is taken, the heart of the system will be the file and printer server(s). In a high speed LAN, the server will typically be a relatively powerful PC. The server holds all files that must be shared among the users. It will also collect printer outputs and route them to a user designated printer. Each floor of the office building can have both a laser and dot matrix printer to which printed output can be directed. Each user will thus have easy access to whichever type of printer he or she needs. Moreover, each PV can have its own dedicated printer if necessary. Kochar, for instance, can have a local printer in her office to print payroll and financial information.

A dedicated server solution will probably require that Pinnacle acquire a new computer to operate as a file server. One of Pinnacle's AT machine could conceivably function in that role; however, using one of the existing systems as a dedicated file server will cause a shortage of PC's. Moreover, the file server will likely need a larger disk drive, more memory, and higher processing speed than is found on any of Pinnacle's systems.

If the file server is the heart of the LAN, the LAN software is its brain. LAN software must reside both in the server and in each PC. This software directs the data traffic between the server and PCs. For example, in a PC, the LAN software will direct file requests either to a local disk or to disk on the file server. The software that does this is called the re-director because it redirects requests from the local system to the server. The LAN software running in a PC also provides the software interface to the LAN medium. In the server, the LAN software is responsible for accepting requests and acting on them. The requests can be for file or print services. The server uses a special operating system designed to expedite the service functions.

File services include downloading a program, accessing records in file, or accessing an entire data file, like a word processing document. Print services include accepting print requests and storing them until the current print job is completed. Then, the server typically sends the collected output to the proper printer, alternatively, the print job might be retained on the server for printing later or it may be both printed and retained for printing on another printer or for later reprinting.

Another function the LAN software might provide is file contention resolution. Many of the PC software packages were originally written to operate in a stand-alone environment.

That is, they were not designed to have several different users accessing a file at the same time. LANs, however, allow several users access to the same file. Although the advent of shared environments like LANs has prompted some software vendors to provide contention resolution, some still do not. At Pinnacle, for example, two LAN users could potentially access the same word processing document, change it, and then place it back on the file server. If two people are updating the same document at the same time, the last person to place the document back on the file server will erase the changes made by the other user. Contention resolution capabilities prohibit two users from simultaneously accessing and updating the same record or file.

Communication with Insurance Carriers

Gupta next asked how Pinnacle proposed handling communication with the insurance companies. Pinnacle can operate in the current mode using the two terminals and modems. Alternatively, a shared system ought to be able to accommodate modem pooling and switched data communications with Pinnacle's insurance companies. A LAN can do this by having the modems attached to the server. An employee can then establish a connection from his or her PC through the server. Thus, it will not be necessary for an employee to move to one of the terminals to prepare a quote.

An added benefit is that Pinnacle can use standard input form and have a program translate the data into the formats required by individual insurance companies. Some Programming work will need to be done if the common format approach is used Pinnacle will need to contract with someone to get the program written.

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Case Study by: Marketing Research Team, 3EA