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PCIe 2.0 switches offer 90, 80 lane options

Posted: 30 Mar 2009 ?? ?Print Version ?Bookmark and Share

Keywords:PCIe switch? lane option 80 90? PCI Express?

PLX Technology Inc. has introduced four new high-performance PCIe switches targeting servers, enterprise storage, control planes and ultragaming, while featuring the highest lane counts. PLX continues its strong market lead with over 60 percent PCIe switch market share and is the only switch supplier with 96 lane and 80 lane options, as well as x16 support which is critical for designers requiring the highest levels of performance and throughput, such as graphics and backplanes.

The new PLX ExpressLane PEX 8696 (96 lanes, 24 ports), PEX 8680 (80 lanes, 20 ports), PEX 8664 (64 lanes, 16 ports) and PEX 8649 (48 lanes, 12 ports) are PCI-SIG PCIe 2.0 (Gen 2) specification-compliant switches with distinguishing PLX-only features, including support for x16 port configurations and non-transparency (NT), as well as visionPAK and performancePAK development tools. The new PLX devices also implement game-changing multi-root and multicast features. These large switches allow designers to build switch fabrics, redundant backplanes and large I/O /storage drawers without having to deal with high latency, high power consumption and bandwidth limitations associated with use of multiple smaller switch chips.

The standard multicast feature was added to the new PLX switches to increase performance by reducing CPU load. Multicast delivers data to a group of destinations simultaneously, thus efficiently using memory bandwidth at the source and relieving the host from copying the data to multiple locations sequentially. PLX chaired the working group at the PCI-SIG that created this standard. For use in backplane applications, PLX switches support fully non-blocking internal fabric and full peer-to-peer data exchange at full Gen 2 line rate without any host assist. PEX 8696 supports a total raw throughput of up to one terabit per second in full-duplex mode at PCIe Gen 2 rates.

The multi-root/multi-host feature of PLX switches offers two modes of functionality. Mode-1 enables one host port to control up to 23 endpoints, or all 24 ports communicate in peer-to-peer mode in backplane applications, where one port can be configured as NT. In mode-1, NT capability can be used for fail-over and redundancy. Mode-2 expands on this with up to eight host ports. This allows for partition in up to eight independent switches with each switch having full isolation and one independent host and several endpoints. In fail-over mode, independent hosts can exchange status or heart-beat information. When a fail-over is triggered the end-points associated with failing host are automatically moved to a back-up host without impacting the traffic between the back-up host and its existing end-points. The endpoints in one host domain can also be moved to another host domain under software control for I/O sharing.

Support tools
An exclusive set of diagnostic and monitoring features called visionPAK are integrated into all PLX Gen 2 switches and are focused on getting designs to market faster. Offered standard via the PLX software design kit, visionPAK includes the ability to access internal data paths and state machines for debugging systems; a tool to measure Rx eye-width inside the device for validating signal integrity; a function to inject errors to check system behavior; loopback Tx to debug data paths, and the capability for packet performance/activity monitoring. Also fully integrated into all PLX Gen 2 switches is the PLX performancePAK, which provides designers additional functions to reach peak performance and includes Read Pacing to fairly allocate host port bandwidth, along with Dynamic Buffer Allocation to absorb fluctuations in bandwidth demand.

"High-lane-count PCI Express switches such as PLX's newest ExpressLane devices will meet many of the needs of blade and rack servers, communications, and enterprise storage," said Jag Bolaria, senior analyst at the Linley Group. "We anticipate continued growth in PCIenotably at the device level, as well as in the expanding array of applicationswhich, along with these new switches, should enable PLX to remain a leader of PCIe switch technology."

"Designers developing products with large switches like these can eliminate the need to use multiple switches and inherently save cost and board space while improving performance," said Krishna Mallampati, PLX marketing director of PCIe switch products. "Also, PLX is the only PCIe switch vendor to offer integrated NT, which is extremely useful in applications that need redundancy and host isolation. We now have 18 Gen 2 switches with NT thus enabling a broad variety of designers to use a 1-chip solution for their redundancy needs."

The PEX 8696, PEX 8680, PEX 8664 and PEX 8649 volume prices are $148.15, $127.75, $105.85 and $78.40, respectively, and will be sampling in Q2 09.

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