Gigabit Ethernet: Transforming the Network Landscape
By Bob Hult, Bishop & Associates Inc.

Staying current in the fast-moving electronics industry can be a challenge. Advances in materials and technologies can quickly convert today’s state-of-the-art products into tomorrow’s dinosaurs. The key to achieving long-term relevance is the ability to embrace the ever evolving demands of the market.

The Ethernet standard for local area networks (LANs) is a perfect example of a technology that has constantly evolved to address the increasing performance demands of the industries it serves. Originally developed in 1973, Ethernet has become the key technology underlying the majority of LAN topologies in use today. From its modest beginning using a single coaxial cable bus running at 10 Mbit/s, Ethernet has evolved to support today’s advanced systems, which utilize economical unshielded twisted-pair cable terminated to low-cost RJ-45 connectors, and operate at up to 10 Gbit/s.

A typical switched Ethernet LAN allows an infinite degree of customization to address specific needs of the user. Ethernet nodes, hubs, and switches can be interconnected via copper wire, fiber optic, or wireless RF links. 

Recognizing the importance of reliable networks, the Institute of Electrical and Electronics Engineers (IEEE) created a committee in February 1980 to standardize network technologies. This new commission was named the 802-working group, after the year and month of its formation. Subcommittees of the 802-working group are designated to explore different aspects of networking. The charter to analyze emerging needs and technologies, and respond with extensions within the basic framework of the Ethernet specification, has resulted in a networking communication technology that dominates the industry today.

A variety of market segments have adopted Ethernet protocols and adapted it to their specific needs.

Server blades in the telecommunications industry run Internet Protocol (IP) over 1 gigabit or 10 gigabit Ethernet links. Ethernet has become the communication mechanism of choice for newer open-architecture systems, such as Advanced TCA and MicroTCA. New applications are also appearing in the embedded computing market.

The ability of Ethernet to support multiple signaling protocols has created many new applications in industrial control. Demonstrating flexibility, industrial Ethernet users have standardized on several connectors that can survive their severe operating environments. Industrial Ethernet applications may use a variety of both copper and fiber optic interfaces.

The standard RJ-45 connector has been adapted for industrial environments by enclosing the contacts in protective shells that may also offer waterproof sealing. 

SCRJ fiber optic connectors are terminated to multimode glass fibers. 

Traditional M12 connectors with D-coding are well suited to Ethernet signaling.

The installation of wireless Ethernet (802.11) sensors in industrial applications have revolutionized process control monitoring and management, as sensors and actuators can be easily added or removed from the network without wiring changes. The same system is utilized in small home and office personal computer networks.

Networks allow the sharing of data to each connected node, but remote devices such as sensors, security cameras, and displays also require power, making installation of these devices more difficult and expensive. Ethernet IEEE 802.3af provides a solution by integrating the delivery of 48 volts DC at up to 350 mA (about 15 watts) of power via unused pairs within the signal connector. Power-over-Ethernet (PoE) enables the simple configuration of networks with minimal wiring. Temporary applications can be quickly installed and modified without the need to install costly power lines. In keeping with its heritage of constant evolution, the next extension is already in the works. PoE+ will increase the power delivery capacity of Ethernet to 56 watts, enabling the attachment of self powered WiMAX transmitters, pan/tilt and zoom cameras, as well as videophones.

Ethernet is even penetrating the backplane market via the 802.3ap standard, which specifies 10 gigabit copper PCB trace channels up to 40 inches in length. This standard does not define a specific backplane connector, allowing designers to select any interface that can meet the performance requirements of the specification.

A more recent Ethernet upgrade reflects the market demand for greater bandwidth. Ten gigabit Ethernet (10-GbE) was ratified in 2002, and is now being widely implemented in data center applications, such as aggregating lower speed data streams. Ten-GbE has also been considered as a possible alternative to Fibre Channel in storage applications.

Metro and campus implementations of 10-GbE use optic fiber, while applications within a building, may be optic or copper links. Inter-rack and in-box applications are typically copper. The use of transceiver modules, such as XENPAK, support both copper and fiber cabling options.

The IEEE 802.3an amendment defines 10 gigabit Ethernet-over-twisted-pair cable. Category 6 cables can run up to 55 meters, while Cat 6a and Cat 7 cables can perform at distances of up to 100 meters, using optimized RJ-45 plug connectors. PCB jacks may incorporate capacitive compensation features.

Connector suppliers, such as Bel Stewart, have developed enhanced RJ-45 plugs and jacks that satisfy the 10 GbE Ethernet standard. The conductor twist is carefully managed in the plugs and capacitive compensation is integrated into the PCB receptacle.

The SL series AMP-Twist shielded modular jack from Tyco Electronics is also designed for 10 GbE applications.

The RJ-45 workhorse connector may finally be reaching its performance limits. A more popular implementation of 10Gb Ethernet has been using twinaxial cable terminated to Infiniband CX4 connectors. Each lane carries 3.125 gigabits of signaling bandwidth, with plenty of headroom to support next-generation Ethernet standards.

The continuing effort to stay ahead of the technology curve is driving the next step to higher speed Ethernet performance. The IEEE 802.3 Ethernet Plenary and High-Speed Study Group have recently held joint meetings to hammer out the ground rules for 40 and 100 gigabit  Ethernet standards. Few applications exist today that require these speeds, but 40 gigabit is seen as the next logical progression in performance, while 100 gigabit links could be achieved using four lanes of 25 gigabit data streams. Debate among potential users regarding the development priority of 40 versus 100 gigabit Ethernet resulted in the decision to pursue both. Many issues, such as the availability of chips, assembly processes, test procedures, as well as limitations of copper cable must be resolved before standards can be created.

Both fiber and copper implementations are expected for the 40 gigabit version, and camps are taking positions on the most effective copper interface. One approach may be using Cat 7a, a fully shielded cable terminated to a modified RJ-45 connector that locates contact pairs in each corner of the connector for improved isolation. The Bel Stewart ARJ45 series of plugs and jacks are being proposed as a possible solution in 40 gigabit Ethernet applications.

Others are betting on the CX4 connector to satisfy performance requirements of the 40 gigabit Ethernet standard, which may be ready for ratification by the end of 2008. Proposals for a copper option to support 100 GbE have been made using up to eight pairs in a shielded cable. Cable lengths would likely be limited to five to 10 meters.

By pushing the bandwidth frontier today, Ethernet continues to address the application needs of tomorrow.

Bishop & Associates Comments:

• Ethernet has a long history of anticipating market needs and addressing them with advanced network communication technology.

• Although Ethernet has undergone almost continuous upgrading in both performance and features, it has retained its basic frame structure, which assures backward compatibility among all versions of the standard.

• The development of Power-over-Ethernet has greatly expanded applications in remote sensing, process control, and video surveillance.

• Ethernet is designed to communicate via several configurations of copper, as well as fiber optic cables and connectors. Copper interconnects remain the most cost effective, but are limited to relatively short lengths.

• Traditional and enhanced RJ-45 connectors may be nearing their performance limits, as interfaces such as CX4 terminated to twinaxial cables become the preferred media.

• Ethernet is winning the networking race in such diverse markets as industrial control, military, computing, and even carrier segments.

• Ethernet continues to evolve with higher bandwidth capabilities driven by applications that range from Voice and Video-over-Internet-Protocol to high-speed data center, switch, and server installations. As speeds continue to increase, higher performance connectors and qualified cable assemblies will represent excellent growth potential.

• Forty and 100 gigabit Ethernet are the newest emerging bandwidth targets, and will provide performance headroom for many generations of advanced networked equipment.

Robert Hult
Director of Product Technology, Bishop & Associates, Inc.
Robert Hult has been in the connector industry for over 36 years. Hult began his career as a sales engineer for Amphenol. He joined AMP in 1972 and served in several management positions through 1996. In 1997, Hult joined Foxconn as group marketing manager for Intel, Chandler, Arizona, U.S.A. Prior to joining Bishop & Associates, Hult was the regional application engineering manager for Tyco Electronics.

Hult graduated in 1968 from Bradley University with a Bachelor of Science degree in electronics technology and a minor in business.