Fast Ethernet to GbE migration drives massive Ethernet switch upgrade

Jasmin Tremblay, Agere Systems -April 24, 2006

Gigabit Ethernet (GbE) flourishes as the new high-speed standard networking interface for enterprise equipment, while network activity in the business world swells to previously unimaginable levels in both volume and capacity. Emails by the million, whether they deliver small 10-kilobit messages or super-sized 10-gigabit videos, constantly crisscross the global desktop. The high volume of data-laden traffic however, exerts mounting pressure not only on existing network processes, but also builds a strong case for the expanding role of the Ethernet multi-port switch.

While the demand for high-density Ethernet switches is growing, switch technology is reshaping to accommodate the more efficient wire-speed, jumbo-size packets. Network managers with an eye for the future are calling for practical, customizable systems that can keep pace with ongoing network advancements. Vendors are beginning to respond with economical, scalable, high-performance/high-density GbE switching solutions that are easy to manage.

A massive Ethernet switch upgrade is under way as the migration from Fast Ethernet to Gigabit Ethernet accelerates. The continued deployment of VoIP, WLAN, and new Ethernet-enabled devices drive the need for bigger, faster processing payloads as well as multi-port switches designed to handle them. In addition, network administrators face increasing difficulty in estimating port growth. As the demand for more ports is rising, the market price for higher-density switches is falling, thereby stimulating new business environments. The information offered here reviews these trends, their impact on network processes, and the ensuing opportunities in the Ethernet switch market segments. It also examines the competing architectures of today's popular 48-port GbE switch solutions.

Applications justifying large-packet payloads
By now, the sales of GbE ports have surpassed Fast Ethernet (100 Mbits/s). The wide adoption of Gigabit Ethernet has enabled a number of new applications. Some of these applications are driving up the need for wire-speed, jumbo-frame processing. The speed of links and processing capacity of Ethernet switches has increased dramatically, although the average network maximum transmission unit (MTU)--the generally accepted value that defines packet size--is relatively unchanged at 1500 bytes. As a result, the newly acquired GbE capacities are not fully utilized. (Efforts are afoot within the industry however, to increase the MTU. Applications that are driving the need for increase packet size are examined below.

Video over IP
High-bandwidth services, such as IPTV and corporate desktop web casting and interactive video (video over IP), require evermore network capacity and processing. Using jumbo frames to support these services, however, can increase the use on Ethernet links and lighten the load on equipment that must fragment the frames. For these applications, the application server can often be the bottleneck. Increasing the MTU reduces the amount of fragmentation the server needs to perform.

For example, using an MTU of 1500 bytes, a 64K frame must be fragmented across more than 40 frames. Increasing the MTU to 9000 bytes, however, reduces the fragmentation by more than 80%. This becomes even more important when transmitting bandwidth-hungry, uncompressed HDTV.

Storage over IP
Jumbo frames (untagged frames of 1518 bytes or tagged frames of 1522 bytes or more) are ideally suited for a number of commercially available storage-over-IP solutions using iSCSI or FCIP. They reduce both server load and the network load, and subsequently, the time required to perform backups. Conversely, smaller frames usually generate more interrupts and processing overhead. In some cases, jumbo frames provide 50% more throughput with 50% less CPU load than 1500-byte frames. Even so, most of these applications are still using smaller packet sizes because jumbo frames are often unsupported by the network equipment.

Data warehousing/data mining
With the wide deployment of enterprise information systems in large companies, huge data warehouses are now being used for business intelligence applications. It is common to find multi-gigabit queries launched against data warehouses using web-based tools. Even with GbE interfaces, the network is increasingly becoming the bottleneck to deliver acceptable response times. Large MTUs are recommended to increase the performance of returning large amounts of data over a network.

IPv4-to-IPv6 migration
IP packets are often larger than 10 Kbytes. Consequently, costly fragmentation occurs as soon as they traverse Ethernet switches. IPv4 datagrams are limited to 64 Kbytes; with IPv6, this limitation will grow to 4 gigabits. Using jumbo frames to increase network efficiency is conceptually sound but, in many cases, cannot be applied due to equipment networking limitations

GbE switches at higher densities
Desktop connectivity requirements continue to evolve. Office computers are now being shipped with GbE network interfaces. Meanwhile, the price of GbE ports across networking equipment has dropped significantly. New applications are taking advantage of the available gigabit speeds, thus driving up the port requirements. Three of the market trends that are pushing Gigabit Ethernet switches to higher densities are examined below:

  • New applications and devices.
  • New business dynamics.
  • The market price erosion of higher-density port switches.

Increased port-count requirements
The number of Ethernet ports in today's businesses continues to increase. Computers are now fully networked, but other devices are yet to be upgraded with Ethernet capabilities. In several types of businesses, there is a continuing increase in the requirements for Ethernet ports. A few examples are presented below.

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