Vitesse Joins Next-Gen Sonet Party
The company has launched two chips: the VSC9118, an OC192 (10 Gbit/s) or quad OC48 (2.5 Gbits) virtual concatenation mapper; and the VSC9115, which is a single-port OC48 version. Virtual concatenation is a technique for "right-sizing" Sonet channels so they can carry data traffic without wasting bandwidth -- by grouping an arbitrary number of STS1 (51.8 Mbit/s) units together.
When the majority of chip makers unveiled their first set of next-gen Sonet products in the first half of this year, Vitesse was noticeably absent from the group (see Next-Gen Sonet Silicon). In fact, it was pretending not to care, even while it was hard at work playing catchup behind the scene, according to Simon Stanley, principal of Earlswood Marketing Ltd., a U.K. consultancy, and author of several Light Reading reports on communications chips (see Traffic Manager Chips, 10-Gig Ethernet Transponders, and Network Processors).
Like other chip vendors, Vitesse eventually realized that there was more money to be made from Sonet-based than from packet-based silicon for the foreseeable future. So, it's gone full speed ahead on the former, while pulling right back on the latter (see Vitesse Drops Some Packets).
Being a little late to market, however, Vitesse felt it needed to come up with something significantly better than the competition, says Fotis Konstantinidis, product marketing manager for the company's new Sonet chips. And it may have just managed to do that.
For a start, it's one of only a handful of vendors to announce a 10-Gbit/s part, another being Multilink Technology Corp. (Nasdaq: MLTC) with its MTC6210 framer (see Multilink Makes Sonet Flexible).
As a basic requirement, both parts support GFP (generic framing procedure) and LAPS (link access protocol SDH), which are basically new ways of mapping data packets into Sonet. And both chips do virtual concatenation and LCAS (link capacity adjustment scheme), a method of adjusting the size of channels allocated to different services (see Next-Gen Sonet , page 3, for a more detailed explanation of these terms).
The other area where Vitesse's new chips seem to shine is in the number of logical channels they can support -- 64. This allows a chip to carry more distinct streams of data, which is a useful feature where there are lots of lower-speed connections such as Fast Ethernet to be aggregated onto a single Sonet pipe.
The next best number of logic channels available is 48, in chips from TranSwitch Corp. (Nasdaq: TXCC) and West Bay Semiconductor Inc. (see Next Gen Sonet: What About SDH?).
The jury's still out, however, on whether Vitesse has picked the best way to partition the work among different chips on the line card. Its chip performs framing and mapping only -- it needs to connect to a separate physical layer (PHY) chip in the case of a Sonet connection, or an Ethernet MAC (media access control) chip in the case of packet data. Other vendors, such as PMC-Sierra Inc. (Nasdaq: PMCS) have integrated these functions, thus saving its customers the cost of buying a second chip (see PMC Pushes Sonet Silicon).
Vitesse's Konstantinidis counters by saying that the approach was chosen for its flexibility. One chip can interface to Sonet, Ethernet, Asynchronous Transfer Mode (ATM), or any other type of network, simply by pairing it with an appropriate companion chip. The VSC9118 supports SFI-4 (SerDes-framer interface) and SPI-4.2 (system packet interface) connections, which are the industry standards for 10-Gbit/s equipment.
Vitesse's new chips are slated to sample next month and reach production quantities by the first quarter of 2003. The VSC9118 is priced at $960; the VSC9115 at $480 each in sample quantities.
The announcement means that there is now only one other prominent player in the framer/mapper space -- Applied Micro Circuits Corp. (AMCC) (Nasdaq: AMCC) -- that still doesn't have any next-gen Sonet offerings.
— Pauline Rigby, Senior Editor, Light Reading
www.lightreading.com Want to know more? The big cheeses of the optical networking industry will be discussing next-generation Sonet at Lightspeed Europe. Check it out at Lightspeed Europe 02.