Piece By Piece
Bandwidth efficiency is the name of the game
as operators gear up for multiple services
The doom and gloom surrounding the telecommunications industry hasn't done much to curb Internet users' insatiable appetite for bandwidth. In fact, it's increasing. According to Webnoize, the digital entertainment analysis firm, peer-to-peer networks are more popular than ever, even after the death of music-file-swapping phenom Napster. In August, more than 3 billion files were downloaded using the four leading file-sharing systems, Webnoize says. This compares with the 2.79 billion files downloaded using Napster during its heyday in February.
Yet another bandwidth-munching service was created last month (September) when Sonicblue Inc., bolstered by its August 2000 acquisition of ReplayTV, introduced ReplayTV-branded digital video recording boxes with broadband connectivity.
Throw in cable operators' interest in adding voice, data and interactive video services to an already-overloaded network, and it's easy to see why these developments are reinforcing the importance of bandwidth management technologies.
Much like the game of Tetris, where players are rewarded for their skill in placing variously shaped puzzle pieces as tightly together as possible, cable network operators are increasingly focused on using their bandwidth efficiently by packing numerous services in a limited space.
Importantly, bandwidth management has to be addressed at the very beginning of a data deployment, says Bob Williams, director of engineering for Adelphia Communications. "The problem is, nobody really has a good idea of where bandwidth consumption is going," says Williams. That is, it takes a very clear crystal ball to predict which services will be winners, and which ones won't. "You can't build a system for an overall 20 percent penetration."
Today, he explains, operators watch usage at network operations centers and upgrade the network, usually by splitting nodes or adding cable modem termination systems (CMTSs), as necessary. "As operators, we have enough trouble running a single-tier service with DOCSIS 1.0 cable modems," concedes Williams. But with DOCSIS 1.1 gear on the way, the dawn of tiered services and quality of service is on the way.
"The train's already left the station," says Williams. Fortunately, there are several vendors developing bandwidth management technologies. "These bandwidth management tools that are in the pipeline are really going to help us," notes Williams.Managing bandwidth with software
Emperative Inc., best known for its ProvEn data provisioning software, has incorporated a bandwidth management subset, called CMX, to provide control of IP services, and modify the amount of bandwidth that a subscriber's modem will allow, according to Randy Fuller, vice president of marketing for Emperative. CMX resides in a server at the headend, separate from the CMTS, and includes both DHCP (Dynamic Host Configuration Protocol) and TFTP (Trivial File Transfer Protocol) components. Fuller explains that when a data customer comes on the network, the DHCP server assigns the user's modem an IP address, and the TFTP sets the modem. CMX can also throttle down subscribers who are using too much network bandwidth, and allow subscribers to change their allowable bandwidth dynamically, if operators choose to offer such a service.
Emperative’s bandwidth management scheme.
Thus for Emperative, bandwidth management is "not only keeping the reins on the heavy users, but also allowing the MSO to offer tiered and premium services," says Fuller. "CMX is the enabler to do that."
Moving into a DOCSIS 1.1 environment, in which policies can be set for various users and services, bandwidth management software needs to be more sophisticated. Fuller points out that software must take a request for a service change and talk to the billing and operations support systems about charging appropriately. An integrated CMX and ProvEn platform can accomplish this, says Fuller.
Emperative's software is compatible with CMTSs from Cisco Systems Inc., ADC Telecommunications, Terayon Communication Systems Inc., Nortel Networks and RiverDelta Networks Inc. (now part of Motorola Broadband Communications Sector). "We can build support for a new CMTS within a matter of six weeks," says Fuller.
Cox Communications is using Emperative's ProvEn provisioning software across its middle America systems, covering over one million homes passed. The MSO is also testing CMX.'Automatic, dynamic bandwidth allocation'
Also following the software path to address bandwidth management is ChanneLogics, which has developed a network access management suite designed to collect information on a per-modem basis, monitor individual usage patterns, predict bandwidth demands and then allocate bandwidth to each modem on a network.
The company's approach anticipates the day when cable operators will offer guaranteed levels of bandwidth at specific times of the day. "We (have) the capability to provide multiple SLAs (service level agreements) by time-of-day to individual subscribers," says Jim Walsh, president of business units for ChanneLogics. Its software uses predictive algorithms and historical data to "talk to CMTSs and dynamically allocate to each individual subscriber based on class of service," time of day and historical use. The software collects cable modem MIB (management information base) data (it can sample MIB data every 2.5 minutes) and stores those usage "histories" in a database. The data can be collected on an individual subscriber, CMTS, CMTS blade or network basis.
By collecting data on each individual modem, Walsh says operators "can identify bandwidth hogs and have the capability to cap them or sell them a bigger package for more bandwidth."
ChanneLogics research has discovered that a typical CMTS, serving between 2,500 and 3,000 data subscribers over a seven-day, 24-hour-per-day period of time, has an average total bandwidth utilization of between 30 and 35 percent. Further, the total bandwidth utilization of a 32-megabit pipe during the hours of 7 a.m. and 5 p.m. is under 10 megabits, ChanneLogics has found.
While cable operators have been generally focused on best-effort residential data service, they may be able to sell and guarantee some of this bandwidth that's unused during the day, to business users, for example. If an operator's service area contains a business park next to a residential area, that business park would be a good candidate to sell bandwidth to during the day, while reserving bandwidth for residential users at night. At the same time, operators will be raising the overall capacity of the CMTSs serving that area.
ChanneLogics is currently involved in three separate field evaluation trials of its software with "more than one MSO," says Walsh.Big iron
Embracing a dual hardware/software solution to bandwidth management is BigBand Networks Inc. But BigBand is looking beyond just managing data services on HFC networks, according to Amir Bassan-Eskenazi, CEO and founder. IP data services are a small portion of the overall pie, he says. Bandwidth management techniques "have to take a hard look at the video portion of things," he says.
Despite the demise of Napster, peer-to-peer application use is accelerating, according to analyst firm Webnoize, justifying a deeper look into bandwidth management techniques.
BigBand scored a big win in May when it announced that Cox Communications will be using the BMR. "Cable spectrum is a valuable resource for Cox," says Michael Pasquinilli, director of iTV technology for Cox, in a press release. "We can maximize that value by continuing to find more efficient ways of using bandwidth for new advanced services. The NativeMedia operating system ... enables us to do so by sharing bandwidth across multiple services ... As we continue to expand our deployment of advanced services and build our network infrastructure, we have selected the BMR as a component in our architecture."
Bassan-Eskenazi says that BigBand is working with several operators to introduce the BMR into networks for grooming 6-MHz channels. The router typically would be placed in a headend or large hub. The router's processing and routing engines are able to effectively "packet-switch" MPEG and IP packets and adjust what goes into each channel, according to Bassan-Eskenazi. Total bandwidth, then, can be managed within the constraint of a 6-MHz per channel configuration.
The routing engine is a hardware-based component with a 32 Gbps switching fabric or backplane. The router and OS, in effect, create a "bandwidth on demand network." NativeMedia can control, through the processing engine, MPEG multiplexing, IP encapsulation, statistical multiplexing, data and video transcoding, video over IP output, and splicing for real-time insertion of content from different sources.Bandwidth management dream team?
Finally emerging publicly into the bandwidth management fray is Stargus Inc., with a strong cast of cable industry veterans, including board chairman Rouzbeh Yassini, executive consultant to CableLabs' DOCSIS initiative; Russell Stephens, president and CEO, a former senior vice president of MediaOne's Northeast region; and Robert Cruickshank, vice president of business development, former leader of CableLabs' DOCSIS development, interoperability, standardization and certification programs.
Stargus' broadband access management system combines both software and hardware components–rack-mounted network management boxes with small footprints placed on the regional rings of large networks to collect data, and software to massage the data to provide real-time information about bandwidth usage. Approximately 30,000 cable modems can be supported with each box.
According to Stephens, Stargus' system is designed to "maximize network availability and utilization" by detecting plant problems and fixing them. Stargus' focus is on new IP-based services and putting a network management system in place to "locate and predict plant problems," says Cruickshank.
The Stargus approach relies in part on MIB information produced by cable modems activated on HFC networks. This information, according to Cruickshank, can help operators provide reliability not only for data services, but for voice-over-IP applications and advanced IP services such as streaming media.
MIB information can produce hundreds of kilobits of data per modem as more than 300 items are measured as per the DOCSIS specification. With millions of modems potentially connected to a network, the amount of aggregated MIB information clearly becomes unmanageable. Introduce an open access environment into the network, and conditions become even more complex.
Stargus' system is designed to "distill" MIB data and "talk" to all devices on the network. The customizable platform identifies and proactively addresses plant degradation, manages and measures traffic on both a network and single-user basis, tracks cable modem inventory and device configuration, ensures service level agreement (SLA) compliance, and addresses network security issues. Importantly, according to Raphael Leeman, vice president of marketing for Stargus, the platform is able to measure at what point in time a certain number of customers on the network impact performance, and in what part of the network traffic is being impacted.
Stargus plans to partner with CMTS makers and others to extend the functionality of its system and integrate with existing systems. Stargus' product suite will be officially announced at the end of the year, although MSOs are now conducting technology trials of the platform.DOCSIS 1.1
The DOCSIS 1.1 protocol gives operators even more network management tools, some of which are based on advanced versions of Simple Network Management Protocol (SNMP). Expect modem vendors, such as Texas Instruments, with its TurboDox modem software, to capitalize on these capabilities to differentiate their products.