Speeding up the gigabit ethernet

Two industry leaders (the Institute of Electrical and Electronics Engineers, or IEEE, and Intel) are working on a means to deliver information (or data) to the user faster, at rates of up to 10 gigabits per second (Gbps). They are:

A copper technology: The recently approved standard for delivery of Ethernet at 10Gbps over four pairs of coaxial copper wiring now known as the IEEE 802.3ak application (10GBASE-CX4), and

A fiber technology: The development of a (silicon) optical modulator that can handle 1 gigabit speeds to move data within a PC or a server, which may work up to a speed of 10Gbps.

This “need for speed” is indeed spreading throughout the industry. Some of the reasons for it are the fast-tracking of datacomm standards, the popularity of the new 10 gigabit Ethernet standard and indications from the copper and fiber physical layer industries that show they can deliver at high speeds, like 10Gbps.

Regarding this desire to go faster, the IEEE has been working on the next speed level of Ethernet with another ten times jump in the data rate. The development of 10 Gigabit (10Gbps) Ethernet is about four years behind Gigabit (1Gbps) Ethernet. Even though the distance is short (about 15m or 75 feet) and the cable is coaxial, what matters is that it is for Ethernet transmission—what most of our LANs use today. Another interesting solution is in the works at Intel, which just announced a new silicon device that can modulate (blending data into a signal) optical interconnects to speed signals from computer to computer or from circuit to circuit, at a much faster rate than the copper wires used today.

10 Gbps over coaxial cable

This is the IEEE spec for 10Gbps transmission over coaxial cable for 15 meters. It runs over the four pairs of the twin axial (coaxial cable that has two inner conducting wires rather than one) copper wiring. This uses the InfiniBand technology which is an interconnect that offers increased system performance (sending data serial rather than in parallel) and can support storage (such as a storage area network, or SAN), networking and communications between processors. It serves to connect servers or switches over short distances (the standard says “to be sure of performance,” keep to 15m), but that distance will probably be pushed. Its big advantage is that it expects to cost half of what a fiber-based 10Gbps Ethernet ports sell for.

The primary applications for 10GBASE-CX4 are:

• As an interface between two switches

• Potentially for an end device such as a server or NAS (Network Attached Storage) attachment to an Ethernet switch in a data center or equipment/computer room.

The latter application will be limited somewhat by its 15m distance range.

The good news is that the 10GBASE-CX4 interface will be less expensive than its fiber alternative (10GBASE-SR), but the bad news can be that the rigidity, the cost of the twin axial cable and the limited distance (again, 15 to 20m) may be potential factors that tie up market acceptance of 10GBASE-CX4. It does, however, have a considerable lead in terms of standardization time on 10GBASE-T and so is worth considering if one needs a near-term 10 Gigabit Ethernet solution at low cost.

Another announcement came out this first quarter of 2004 about a manufacturer’s chip being developed to provide 10Gbps over 30m. This is also with using the InfiniBand technology. These 10Gbps uplinks and interconnects for the enterprise and the data center are being introduced because of the trend toward “Gigabit to the Desktop” and using networked storage.

1Gbps optical modulation

This is a different approach to high-speed communications. It is the development of a silicon-based optical modulator by Intel Corp. Until now, modulation speeds have been about 20 MHz and the news from Intel is that it has achieved speeds up to 50 times faster by taking a different approach. This could lead to faster and more powerful chips that shuffle data around the Internet using light instead of electricity. This new silicon device modulates light at a rate of 1 GHz and is the first step in developing a set of optical components that can take advantage of silicon to build complete optical systems cheaply. What it does is transmit data by turning on and off to create the ones and zeroes that make up the language of computers. But, instead of electrons, the modulator creates flickers in light beams that can operate at a speed of approximately 1 GHz (meaning it can cycle about 1 billion times per second).

Since optical devices are usually built from uncommon materials that are hard to manufacture and very expensive, using all silicon gives manufacturers the ability to use existing manufacturing processes and techniques and other economies to significantly reduce costs and sizes.

If this technology can improve performance by a factor of 10, i.e., go to10Gbps (since copper cabling used in Ethernet links can lose performance as speeds go beyond 10Gbps), then optical links based on this technology could compete with copper Ethernet in the next level (40Gbps) of Ethernet development.

Applications for this technology include:

• Faster board-to-board interconnects in data centers

• Faster bus (an electrical conductor that makes a common connection between circuits) architecture in personal computers that could lead to faster processing of data within the PC

• Medical imaging that requires a great deal of bandwidth

• Chip-to-chip interconnects

• To replace copper wiring within microprocessors

There are predictions that this method of light-based optical computing may start a new generation of technology. At least in the next two or three years, you will see more optical computing. Copper wires may reach their bandwidth limitations and the optical interconnects may take their place. Computers can only benefit from being faster and more powerful.

The 10GBASE-CX4 application is here. What’s in it for you, the electrical contractor?

• Your customers may have an interest in or may already be using method in their computer rooms or data centers.

• If they are not already using 10GBASE-CX4, they may benefit from your description of this application, because it could save them money, yet give them the speed they want.

• This application became ratified by IEEE in February 2004 and has the formal title of IEEE 802.3ak-2004 “Physical Layer Management Parameters for 10Gbps Operation, Type 10GBASE-CX4.”

The future optical modulation technology is a sure sign that developers are looking for a way to move data at faster speeds than can be done today.

• You can keep yourself and your customers apprised of what is happening and where this new technology may be of benefit to them.

• There may be other methods yet to come, but this method is being worked on now and you can watch its progress by following the Intel technologies. See their Web site www.intel.com.

Customer support and advice are excellent ways to generate revenue. The information presented here is a sure way to help yourself and others by pointing out these two approaches for “communication.” The methods used to communicate are not going to go backwards, so they won’t be moving slower. Keep on top of today and tomorrow’s technologies so you can debate the good and the bad points of design choices. Be the catalyst for change where it’s appropriate and you will find that people will search you out. EC

MICHELSON, president of Jackson, Calif.-based Business Communication Services and publisher of the BCS Reports, is an expert in TIA/EIA performance standards. Contact her at www.bcsreports.com or randm@volcano.net