Pro Series Switch Platforms
ImageStream continues to invest in the development of new Linux-based switching platforms. The new platforms will leverage ImageStream Linux™ and standards-based switch fabrics to build LAN and WAN routing solutions that deliver first generation throughput of at least 32 Gbps.
The following sections provide an overview of ImageStream's product research, as well as a roadmap of upcoming switch platform products. Please contact ImageStream if you would like information on the current availability of commodity switch platform components.
Compact Packet Switching Backplane (PICMG 2.16)
ImageStream's initial switch development has focused on the CompactPSB (PICMG 2.16) standard, which provides ethernet signaling across the backplane. The CompactPSB standard is widely supported by many manufacturers, and it uses the same chipsets that are used in other commercial ethernet switches. Part of the market success of CompactPSB is its ability to use low-cost commodity ethernet switching components to manufacture the industry's lowest cost switch fabric.
The interface cards, or nodes, on a CompactPSB switch are currently limited to 1 Gbps. This means that a network switch based on CompactPSB can support wire-speed operation of WAN interfaces up to OC12/STM4 (622 Mbps full duplex). This level of performance is comparable to that of ImageStream's PCI and CPCI router platforms, except that the CompactPSB switch platform can deliver wire-speed performance with dozens of OC12 interfaces, while the router platform can only drive one or two OC12 ports at wire speed.
Moving beyond 1 Gbps per node is a little more complicated. The PICMG plans to standardize the next generation CompactPSB fabric on 10 gigabit ethernet (10GigE). Next generation CompactPSB systems will provide 10 Gbps per node, and support 10 gigabit ethernet as well as OC48 (2.5 Gbps full duplex) and OC192 (10 Gbps full duplex). A 10GigE switch fabric will also benefit from the commodity components that are being developed for the broader 10GigE market. So despite what happens to the other switch fabric technologies, it is clear that 10GigE CompactPSB will inevitably become a successful switch platform, and ImageStream expects to support the 10GigE CompactPSB platform as an upgrade path for 1 Gbps systems.
The problem with 10GigE CompactPSB is time-to-market. This technology is still on the drawing boards, and there is much weaker demand for 10GigE products than there is for the current GigE implementation. This could result in slower development of the standards and supporting silicon required to bring this platform to market.
Alternatives to CompactPSB
Because of the current per-node limitations of CompactPSB, and because the time-to-market for 10GigE products is still a matter of speculation, ImageStream is continuing its research on alternative fabrics that provide at least 2.5 Gbps connectivity per node. There are a number of switch fabrics technologies that could be used in this application including Star Fabric, Infiniband, RapidIO, and GigaBridge from PLX, just to name a few.
Some switch fabric chipsets are already available, some are nearing availability, and others are still being developed. ImageStream has adopted a "wait and watch" philosophy with regard to RapidIO. While many of the industry's largest manufacturers including Cisco have endorsed this standard, RapidIO continues to suffer from poor market recognition, an initial parallel I/O standard that will be incompatible with future serial standards, and slow development of low-cost silicon.
When ImageStream began its research on switch fabrics in early 2002, GigaBridge from PLX appeared to be a strong contender. PLX makes PCI chipsets, and Gigabridge is the company's proprietary standard for a switched PCI fabric. As a proprietary standard, Gigabridge appears to have fallen behind the rest of the switch fabric market. At this time, board manufacturers have not widely adopted Gigabridge, and so it is unlikely that PLX will be able to develop significant momentum in this market. The market generally avoids the adoption of proprietary standards, and PLX will lose its chance to drive the switch fabric market once new systems that support PCI Express have shipped.
Intel initially planned to develop and market the Infiniband switch fabric. The commitment from Intel gave Indiniband the strongest market recognition in the early days of the switch fabric wars. But since that announcement, Intel has abandoned its plans to develop Infiniband silicon. Mellanox is already shipping Infiniband chipsets, and a few other companies have produced Infiniband switches. But the technology is relatively expensive, and most industry pundits have already declared that Infiniband is dead. ImageStream will continue to watch the development of this platform, but few expect Infiniband to survive in a competitive market with many low-cost alternatives.
Star fabric is another switch fabric standard that supports 2.5 Gbps throughput per node. Star fabric boards and silicon have been available from Stargen for some time, and Stargen has worked with the PICMG to develop the PICMG 2.17 star fabric standard. More importantly, there is encouraging news from Stargen that says the company will no longer push its roadmap for the next generation 10 Gbps Star fabric, but instead work with Intel to define the next generation switch fabric for PCI called PCI Express. With Stargen and Intel lined up behind the new PCI Express switch fabric standard for commodity PC applications, there is no doubt that PCI Express is the heir apparent to the PCI bus, and will inevitably drive a significant portion of the switch fabric market.
PCI Express
PCI Express (formerly known as 3GIO) is the next generation standard for PCI interconnections. PCI Express specifies a switched fabric with high-speed serial I/O interface that is not compatible with existing PCI hardware. The existing PCI bus is a parallel data bus that has serious clock speed limitations when compared to serial I/O. To achieve higher clock rates and still keep component costs low, switch fabric designers have been forced to adopt serial I/O interfaces in place of the existing parallel interfaces. Fortunately for software developers, PCI Express is designed to be compatible with existing PCI driver architectures.
PCI Express has many things going for it. First, the PCI Special Interest Group (PCI-SIG) has announced that PCI Express is the next-generation PCI interconnect standard. This means that PCI Express silicon will be produced in large volumes and have a relatively low cost when compared to other switch fabric chipsets. Stargen has also decided to endorse PCI Express as the next generation Star fabric standard, and has begun work to ensure a smooth transition for developers between first generation Star fabric and next generation PCI Express. With so many switch fabric technologies vying for attention, PCI-SIG, Intel, and Stargen have made it clear that PCI Express will become the most widely deployed switch fabric in the industry.
The PCI Express standard was adopted by the PCI-SIG in July 2002. PCI Express silicon is now available, and board level components should be available by the third quarter 2004.
Conclusions
Industry analysts claim that there are more than 100 different switch fabric platforms that are either already on the market or nearing availability. With so many competing standards, the need to pick a winner the first time becomes an overwhelmingly important research objective.
While it is important for product developers to track all switch fabric technology trends, it is even more important to develop a product plan that will succeed over time. When it comes to commodity switching solutions, a successful product plan will necessarily leverage fabric technologies that achieve significant market success, and offer economies of scale that make components inexpensive.
First generation CompactPSB (PICMG 2.16) is the fabric technology that ImageStream has adopted as its first switching product platform. Next generation CompactPSB systems will also be supported as 10GigE applications become more prevalent, and existing switch fabric customers look for an upgrade path.
ImageStream also plans to support PCI Express as it becomes a widely adopted standard. The standard for PCI Express was developed on a very short timeline, and most industry analysts believe that it will quickly become a thriving standard among PC manufacturers. If PCI Express is successful as expected, it will inevitably supercede the traditional PCI bus in high-performance PC applications such as network routing.
When it comes to the other switch fabric technologies, ImageStream will continue to watch and wait. Any of these technologies could become the de facto industry standard for switch fabric product applications, but this is unlikely based on ImageStream's latest research.
ImageStream's research on switch fabric technology has focused on fabric capabilities, vendor adoption, and high-profile manufacturer endorsements. In this context, it appears that CompactPSB in its first and second generations, and PCI Express will both become successful fabric technologies for commodity switching platforms. These conclusions have led ImageStream to develop a roadmap for using the CompactPSB and PCI Express switch fabric technologies in future commodity switching platforms.
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