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Hybrid switch fabric rolls

Posted: 01 Sep 2006 ?? ?Print Version ?Bookmark and Share

Keywords:hybrid switching fabrics? HybriCore EN6100 switch? EN6240 traffic manager? switch-card redundancy schemes? Enigma Semiconductor Inc.?

Enigma Semiconductor Inc. is exploring new concepts in hybrid switching fabrics that combine elements from crossbar and shared-memory switching chips. The company hopes its approach will distinguish its HybriCore EN6100 switch and EN6240 traffic manager from fabrics based on ATM cells, serial-link connections or non-optimized packets.

The company claims to achieve a performance advantage by using variable-length packets both for the interface to Ethernet or IP services and for switching across the backplane. The first generation of switches usually relied on 64byte ATM cells on both input and output, while second-generation switches from the likes of Dune and Sandburst offered packet interfaces, but retained internal cells for switching.

Enigma uses packets at both internal and external interfaces, but relies on byte alignment and crossbar overspeed to minimize inefficiencies. The effective throughput is up to 360Gbps per switch, while more than 2Tbps full-duplex, non-blocking speed can be maintained across the backplane. Up to 36 links can be integrated in the EN61xx switch family, and as many as 14 switches can be used in a system.

Switch-card redundancy schemes such as 1:1, 1+1, N+1 and N+M are supported. Because the chip can support unicast or multicast traffic, it can work with IPTV designs requiring fast multicast support for IP "channel changing," said Enigma CEO Rob Sturgill.

Each serial link on the chip consists of a Serdes pair, along with a PLL and equalizers in both transmit and receive chains. The receiver equalizer is a nonlinear decision feedback equalizer, while the transmitter equalizer tap can update during transmission. The links support speeds of 2.5Gbps to 12.5Gbps, and they support a variety of codecs.

Enigma offers on-chip serial-link test software, which can provide BER predictions and measurement, and can inject errors. Elements of the serial-link design were licensed from Rambus Inc.

The EN6200 fabric manager chips support 14 serial backplane links and four 400MHz SPI 4.2 links. The management chip can support eight classes of service without the need for external memory.

When used jointly in a system, the fabric and management chips can support 36 40Gbit line cards, 18 80Gbit line cards or nine 160Gbit line cards.

Enigma offers four different fabric managers and two fabric chips with 16 and 36 links, respectively.

The 36-link version comes in two derivatives, one with a standard 10Gbit interface, and the other with a 12.5Gbit overhead interface to support forward error correction.

- Loring Wirbel
EE Times




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