Time-to-Market Factors Influenced Spec

Cox Business Services, with about $400 million in annual revenues, is blurring the line between telco and cable company in the way it selects and deploys vendors in an effort to deliver as much bandwidth to commercial customers as possible. Cox uses OpVista’s dense wavelength division multiplexing (DWDM) metro network technology, which that company’s President Ron Foster said was "designed by telecom engineers … to be sold into telecom." What am I? Appearances to the contrary, Cox is not a telecom, but it’s also not a cablecom, said Dan Estes, Cox manager of transport access engineering. "We don’t necessarily consider the equipment specifications as being telco-centric or cable-centric or anything else; we consider them for reliability that meets customers’ expectations," said Estes. OpVista, he said, provides redundancy and reliability and can be configured to handle multiple simultaneous tasks within the network. It interfaces transparently with synchronous optical network (SONET), gigabit local area network (LAN) and wide area network (WAN), gigabit Ethernet (GigE), fiber channels, and storage area networks (SANs), giving Cox a "very flexible platform" that can be managed remotely, Estes said. "As a DWDM supplier, we’re very pleased with the product and what we’ve seen." It’s also capable of delivering more bandwidth, which comes in handy when moving video. Cox uses that feature to move video on demand (VOD) traffic between a video server with a GigE interface and a hub site with a quadrature amplitude modulation (QAM) translator. While configured like a physical ring, OpVista’s differentiated architecture behaves like a mesh. It also can deliver a whopping 320 wavelengths that could support a 28-node network, if the operator desired. "In reality, 12 nodes are probably about right for the applications that we all see," said Foster, who said about 40 percent of the wavelengths would be active in this configuration, with the rest sitting in reserve. "That means the network is going to physically last for a long time," Foster said. "Some of our installed customers (Time Warner being the other cable player) can’t envision exhausting the capacity for 20 years." Squeezing coax In another effort to squeeze bandwidth, Cox Business Services is using Xtend Networks technology to generate virgin bandwidth above the 860 MHz ceiling on residential networks. Cox then can dedicate that bandwidth to commercial customers overlaid on, but not affecting, the residential network. "Where we have a combination of residential traffic, business traffic, Cox Digital Telephone service in a traditional circuit-switched market and set-top box upstream and status monitoring upstream that requires bandwidth to be set aside … we can put Xtend in a node and take advantage of their bandwidth expansion and provide all kinds of business services over that," Estes said. An Xtend drop-in, he said, provides multiple upstream and downstream channels "that are almost pristine" and can be dedicated to selective customers in pinch situations. "It is a node-by-node decision where you would put Xtend in the network," Estes said. "We are encouraging our markets to take advantage of the technology where the situation warrants." Those markets will not be fiber-rich. "Our first choice for business customers is still fiber," Estes said. "If you have fiber available and it’s economic to do, by all means you extend fiber to the customer where it’s needed." Otherwise, with a $400 million business, you do what’s needed to best serve the end user, whether it comes from a telco-centric vendor or from a chunk of bandwidth that resides above the normal network spectrum. —Jim Barthold Modularization and channel bonding are the big news in the next revision of Data Over Cable Service Interface Specification (DOCSIS) 3.0, which is likely to be in operator labs sometime this year and in products in 2006. The new spec is arriving just as the telcos are pushing fiber-to-the-premises and promises to provide cable with a competitive weapon. DOCSIS 3.0 has a minimum throughput of 160 Mbps with no fixed upper limit, said CableLabs CTO Ralph Brown. Modularization and channel bonding Modularization simply increases flexibility and, thereby, cuts costs. In many instances, it is technically possible to perform processing tasks in more than one location. However, previous versions of DOCSIS were inflexible and predetermined where these tasks were performed. Modularity will provide operators with the flexibility to pick and choose more freely where these tasks occur. For instance, stand-alone edge quadrature amplitude modulation (QAM) devices today are cheap, but their function can be located in the cable modem termination system (CMTS). This approach would require each to be paired with upstream QAM channels. Letting operators decide to deploy more fluidly—at the edge for video and the core for data services—can lower costs, said Brown. The other key addition is channel bonding. As the name implies, this is the ability to bind together channels in the upstream or downstream to increase the amount of data that can be trafficked. Two to 24 downstream channels can be bonded together in these scenarios, according to Mike Cookish, the director of product management for Motorola’s BSR group. The ability to offer large chunks of spectrum is key to the cable industry’s move into the commercial services market. CableLabs considered approaches to channel bonding that occurred at the Moving Pictures Experts Group (MPEG) layer and at the packet layer. Cisco was among vendors pushing the MPEG approach, while Motorola, Arris and Broadcom backed the packet approach. Relying on the packet layer enables more of the "heavy lifting" to be done at the edge. Packets over MPEG Cookish said CableLab’s decision to use the packet-based approach was more based on time-to-market and business considerations than one approach being head and shoulders above the other. Either the approach would do the job, he said. Cookish said waiting as long as possible—until the edge—to differentiate the data offers more effective opportunities to statistically multiplex and otherwise gain economies of scale. This capability is growing in importance as the variety of the data operators are delivering grows. Brown said helping operators prepare for Internet protocol version 6 (IPv6) is also covered in DOCSIS 3.0. —Carl Weinschenk