Fiber's role in fail-safe premises networks

Fiber brings security, redundancy, maintainability, and manageability to fail-safe premises networks.

As we turn the corner of this century, new computing challenges loom ahead. With the advent of e-commerce (electronic business) on the Internet and electronic data interchange (EDI) going on in the background, we are faced with the challenge of creating virtual "fail-safe" and secure premises networks. All business initiatives in the new millennium will be preceded by an "e" or "e-business." It's new and exciting, but only the Internet part is actually new. E-commerce has been going on for quite some time. The banking industry performs financial transactions daily between banks and branch offices, the stock market completes millions of electronic transfers each day, and ATM machines conduct electronic business. And all this information is transmitted over private business-to-business networks, established by individual companies, using EDI. These companies have agreed upon how information will be transferred using private and secure networks.

The Internet is slightly different in that it conducts e-business over public networks. It provides a whole new way of doing e-business because the customer and provider are virtual strangers--they have not previously established a formal process for doing business. There are many companies working to provide instant, secure e-commerce over publicly switched networks. All of these efforts focus around software solutions that use some type of encryption like secure hypertext transfer protocol.

With e-commerce or EDI, the physical networks used must be secure and reliable. In any electronic transfer, the entire transaction from start to finish must be completed and verified before the transaction is considered complete. If any part is not confirmed, the transaction is rejected.

Fiber plays a significant role in fail-safe premises networking by providing several critical features:

• security
• redundancy
• maintainability
• manageability.

Security for e-trade is, of course, a major issue. When it comes to money transactions, there is no end to the amount of security that people want. Many are reluctant to give out their credit card number over the phone, Internet, or even to a clerk in a store unless it is necessary. So there has to be a perceived level of security before people will use any new form of e-commerce technology.

One of the issues in this security puzzle is to prevent unauthorized monitoring of the transacted data. There are rapid advances in security occurring within encryption, firewalls, and the like. Optical fiber, however, provides an additional level of security that shouldn't be overlooked. Fiber is not inductive or capacitive (E or H field), making fiber a very secure media. It is almost impossible to tap into a fiber-based network without being detected.

The network protocols that have evolved around optical fiber, such as FDDI, help build redundancy into corporate networks. By definition, FDDI is a technology that has redundancy considerations designed into it. Since FDDI can support data rates of 100 Mbits/sec over a maximum distance of 100 km (60 miles), it is a great candidate for premises-network backbones, campus environments, and metropolitan-area networks.

There are other forms of redundancy to look for in fail-safe premises networks. A typical Ethernet network today may consist of a series of stackable switches, hubs, bridges, or routers. These devices may be placed on different floors of a building or in different buildings.

A good redundant connection between these devices is essential but can also be problematic. If multiple paths exist in your network, packets can circulate endlessly through a loop, which can reduce the performance of a network and could cause a broadcast storm when new packets are generated to correct the problem.

The spanning-tree algorithm was designed to correct this problem. It detects redundant network paths and inhibits loops by maintaining these alternate network paths as backups. The spanning-tree protocol identifies and prioritizes these paths in case of a network failure. The algorithm and redundant paths are significant tools that help keep the network from catastrophic failure. An enhancement to the spanning-tree scenario is to add redundancy to the individual links in the network, which can be done with devices like redundant media converters. In case of a link failure, these redundant devices can switch links in less then a second. This physical-layer enhancement to the network enables the spanning-tree algorithm to more effectively keep e-commerce transactions functional.

Obviously, if a cable gets cut or disconnected for some reason, a properly designed network with enough redundancy in it will survive. A spanning-tree network will restore within seconds. These are significant issues when it comes to e-commerce. If redundancy is not designed into the network, the amount of downtime could be extensive. A small company could potentially lose significant revenue and productivity if a network fails.

Because fiber-based networks use fewer active components, they typically require less maintenance than copper-based networks. Fail-safe premises networks need a network that is easy to maintain to keep the data flowing. The types of equipment needed to maintain a network include switches, routers, bridges, and other devices with redundant power supplies. If the equipment has to stay operative to conduct business, you need a way to replace the power supply without shutting down the network. Stand-alone networking hardware with external power supplies can be prone to failure. It is essential to look for devices that can be chassis-mounted in rack units with redundant power. These types of chassis systems may also provide manageability.

"Hot swapping" network hardware allows the end-user to remove and replace components without turning off the entire device. It is also a necessary feature for your fail-safe premises network.

Even the best-designed fail-safe premises network, or some part of it, will fail at some point. Failure detection is the responsibility of network management. The simple network-management protocol is a popular software-management protocol defined by the Internet community for TCP/IP networks. It is a communications protocol for collecting information from devices on either a copper or fiber network. It is supported by nearly every networking device and a great tool for keeping networks healthy. Even out-of-sight and out-of-mind physical-layer devices in fail-safe premises networks can be managed.

If a failure in a device occurs, the network-management software reports it immediately. The redundancy of the network compensates for the failure. Maintenance of the failed device can be performed without any further disruption to network performance. This simple scenario describes each part of the fail-safe premises network, which is important and necessary.

Fail-safe premises networks today are designed to conduct e-commerce in real time. There are other areas of fail-safe networks, too, such as system backups and disaster recovery. Each of these can be significant challenges for companies and will vary depending on the size of the network. The telephone network is backed up by battery. Other companies may implement their own elaborate backup schemes. Moreover, disaster recovery can encompass things like computer frames, buildings, or even geographic locations.

Member companies of the FOLS include 3M, AMP, Allied Telesyn, Berk-Tek, Belden Wire & Cable, CommScope, Corning, LANCAST, Lucent Technologies, Ortronics, Siecor, Siemon Co., SpecTran, Sumitomo Electric Lightwave, and Transition Networks.

Cheri Podzimek wrote this article on behalf of the Fiber Optics LAN Section of the Telecommunications Industry Association. She is vice president of marketing at Transition Networks (Minneapolis, MN). Cheri can be reached at [email protected].