May 2005
The Cyberinfrastructure Backplane: The Jump to Light Speed
Linda Winkler, Argonne National Lab


An Ethernet infrastructure supporting traditional networking applications, network storage, and clustering, enables greater compute density and physical consolidation of resources. Industry standardization of infrastructure components offers economies of scale that drive down deployment and management costs and leverage common training requirements. The simplified infrastructure reduces inventory and maintenance costs. Reconfigurable components offer the flexibility to make on-demand infrastructure changes.

A natural fit for 10G Ethernet technology is in the scalable uplink from the data center switches that connect server farms with 1G Ethernet interfaces. The price per gigabit for 10G Ethernet is projected to be 40% lower than for Gigabit Ethernet. As an open-standards-based, forward- and backward-compatible technology, Ethernet has been broadly adopted and understood by engineers worldwide. So instead of building networks of increasing complexity, and facing the increasingly more difficult task of finding engineers trained to manage them, enterprises and service providers can leverage the simple and familiar infrastructure that is second nature to a large majority of network engineers.

10G Ethernet also meets several criteria for efficient and effective high-speed network performance, which makes it a natural choice for expanding, extending, and upgrading existing Ethernet networks: A customer’s existing Ethernet infrastructure is easily interoperable with 10G. Existing Ethernet standards, such as 802.1q for virtual LANs, 802.1p for traffic prioritization and 802.3ad for link aggregation, also apply to 10G Ethernet, making the deployment of 10G Ethernet simply plug-and-play for most enterprises and service providers. The new technology provides lower cost of ownership including both acquisition and support costs versus current alternative technologies. Using processes, protocols, and management tools already deployed in the management infrastructure, 10G draws on familiar management tools and a common skills base. Multi-vendor sources of standards-based products provide proven interoperability.

In the metropolitan area network (MAN) the predominant leader continues to be 1Gb/s Ethernet; however, 10 Gb/s metro systems are beginning to emerge as prices of optical components continue to drop. 10 Gigabit Ethernet is on the roadmap to enable cost-effective, Gigabit-level connections between customer access gear and service provider POPs in native Ethernet format, simple, high-speed, low-cost access to the metropolitan optical infrastructure, metropolitan-based campus interconnection over dark fiber, targeting distances of 10 to 40 km, and end-to-end optical networks with common management systems. While there are pockets of new MANs, many locations are still waiting for better market conditions. MANs implemented using Ethernet technology are inexpensive and ideal for seamlessly interconnecting distributed Ethernet LANs because they require no protocol conversion.

The IEEE 802.3ae 10G standard, ratified in mid 2002, features an interface speed at 10 Gb/s at the media access layer, along with two families of Physical Layer Specifications (PHY): LAN PHY operating at 10 Gb/s and WAN PHY operating at 9.29 Gb/s compatible with the payload of OC-192c/SDH. The 10G standard not only increases the speed of Ethernet from 1 Gb/s to 10 Gb/s, but also extends its interconnectivity and its operating distance up to 40 km. Using 10G WAN PHY allows service providers to use the installed-base of SONET Layer 1 transport gear to provision 10G Ethernet traffic. Because the 10G Ethernet WAN PHY avoids the costly aspects of the traditional SONET, such as stringent grid laser specifications, jitter requirements and stratum clocking, it offers a compelling alternative to traditional SONET interfaces with better price/performance. The ability to send Ethernet directly from an Ethernet switch over a WAN PHY link eliminates the need for expensive Packet over SONET router interfaces.

It's important to note that 10G LAN systems offer fewer alarms and indicators than 10G WAN systems. Unlike on the WAN side, there are currently no explicit standards that prescribe techniques for carrying forward error correction (FEC) to extend the reach of 10G LAN PHY. As a result, equipment manufacturers are developing proprietary interfaces to carry 10G LAN PHY with FEC for metro applications. This lack of explicit standard raises the question of interoperability and third party testing. Efforts are under way to develop standards that will make Ethernet services “carrier class” by incorporating operations, administration, and maintenance capabilities.

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Reference this article
Winkler, L. "Does 10G Ethernet Measure Up?" CTWatch Quarterly, Volume 1, Number 2, May 2005. http://www.ctwatch.org/quarterly/articles/2005/05/does-10g-ethernet-measure-up/

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