A look at 10GBase-CX4

In February, the IEEE approved a standard for 10 Gigabit Ethernet over copper, opening the way for short-reach, high-speed data center links that are more affordable.

Our Technology Update author this week takes a look at the standard and what it means.

First off, the 802.3ak standard is also known as 10GBase-CX4 because it is intended to run over CX4, or four pairs of twinaxial copper wiring – best known for its use in IBM’s AS/400 environments. It’s main goal is to connect servers or switches over short distances – under 300 feet – and is expected to cost half of what a fiber-based 10 Gigabit Ethernet port sells for (as much as $70,000 from some vendors).

According to our author (dan.dove@hp.com) 802.3ak is economical because it reuses portions of 802.3 and other standards to simplify and lower the cost of implementation. For example, 802.3ak specifies the same type of connectors and cables now used with 4X InfiniBand, letting vendors incorporate 10GBase-CX4 capability directly within integrated chips. It also minimizes design, installation and maintenance costs by preserving 802.3 network architecture, management and software features.

Rather than attempt to transmit 10 gigabits over a single copper link, the 802.3ak specification uses four transmitters and four receivers operating differentially over a bundle of very thin twin-axial cables to transmit 2.5G bit/sec each at a baud rate of 3.125 GHz per channel with 8B10B coding, our author states.

The major Ethernet vendors Cisco, HP and others are expected to support this new standard in products.