Velio Cleans Up
SerDes chips cure one of the optical network's more embarrassing complaints: As data rates go up, the maximum distance a signal can travel over a backplane shrinks to less than what's needed to get from one card to the next.
Velio figures its chips will avert total disaster. One of its 3.125-Gbit/s, eight-lane SerDes devices will make it possible to build systems using more than a meter of printed circuit board line and two backplane connectors, the company claims. That's twice the objective described in XAUI (eXtended Attachment Unit Interface) -- pronounced "Xowie" -- the emerging 10-gig Ethernet standard from The Institute of Electrical and Electronics Engineers (IEEE).
If signals need to travel farther than this, very-short-range (VSR) Sonet optical links would be more suitable, says Bill Woodruff, Velio's vice president of marketing (see OIF Sets Short-Range Sonet Standard).
Right now, Velio figures that it's the only company to meet the 10-gig Ethernet standard with a single chip. Though other chip makers are in production of 3.125-Gbit/s SerDes -- the highest bit rate available -- their devices don't have enough lanes. Four 3.125 Gbit/s lanes are needed to transmit a 10-Gbit/s signal (there's a 25 percent overhead for encoding) -- and that is what's specified in the standard. Velio offers chips with four and with eight lanes. It says the chips are available for evaluation now and will be ready to ship in volume in Q2 2001.
However, Velio may not hold its unique position for long. Conexant Systems Inc. (Nasdaq: CNXT), for example, is in full production of a single-lane 3.125-Gbit/s device and has a quad version in the works, which is slated for production in Sept 2001, according to Elie Massabki, director of Conexant's transceiver division. (Other chip makers did not return calls.)
But even when other chip makers catch up in terms of capacity, Velio still thinks it will have an edge. For starters, claims Woodruff, it gets better performance than its competitors. Velio uses something called "pre-emphasis" -- boosting certain parts of the signal to make up for the losses in the printed circuit board or backplane. Pre-emphasis is programmable: Tweak it gently for a short link, or wind it right up for a long one.
Second, Velio claims its chips have very low power consumption. The eight-lane 3.125-Gbit/s SerDes device consumes 2.1 watts -- which is about the same as Conexant's four-lane device.
Woodruff sums up: "A customer architecting a next-generation box will use our [SerDes] technology because it gives them a better design margin."
Later this year Velio plans to introduce a chip that integrates SerDes functions with a high port-count switching fabric (see Velio Claims Switch Silicon Breakthrough).
Interestingly, two manufacturers of optical switches with electrical cores -- Tellium Inc. and Ciena Corp. (Nasdaq: CIEN) -- have lent their validation to Velio's press release today (see Velio Introduces Transceiver Suite). Though not officially named as customers, the odds are that both Tellium and Ciena are buying from Velio.
— Pauline Rigby, senior editor, Light Reading, http://www.lightreading.com