Abbreviated as P2P, peer-to-peer networks link constituent PCs to behave as servers and clients, without a master controller, unattended, through all hours of day and night, to share stored files, information, and, especially, music and video. Each computer is a peer to the next. Think of your office LAN, multiplied by as many PCs as are Internet-connectable, all behaving as video servers, and you begin to fathom the enormity and scare of P2P networks — both to copyright holders, and network owners.

The P2P fear factor for owners of cable broadband networks is directly correlated to the scant amount of upstream bandwidth they operate, between 5-42 MHz. As a fraction of total available bandwidth, cable’s upstream path is about five percent. P2P clients sending up big video files risk clogging an already scarce resource.

As of mid-2004, video represented 20% of the traffic surging through Internet routers; six percent of broadband users used 60% of available bandwidth. As a direct result, much of the development in broadband technologies in 2004 came from companies that invented ways to shunt or slow P2P activities. It’s a to do list that will likely never end, or at least so long as there are networks with smart computers at the end points, and broadband in-between.

One chunk of a sliced-up digital message. In data communications, messages get diced into packets, for ease of transport from source to destination. Often, and especially over the Internet, the packets composing a message travel distinctly different routes to get to the destination; at the destination, the packets are reassembled into the original message.

Depending on how the packets are sent, they can be of a fixed or variable length; predictably, there is a correlation between packet size and transmission time. The maximum length of a packet is a few thousand bits. Each packet includes, on its front-end, identification bits, called the “header.” The packet header includes synchronizing information to establish timing at the receive end; some packet headers include source as well as destination information, error correction mechanisms, and clock information to more exactly handle timing issues. All of the stuff in the header is known as “overhead,” when calculating effective throughput rate and quantity; the rest is called the “payload.”

Thinking of it along postal system lines, the packet is the envelope. The payload is the letter. The header is the destination address, and sometimes the source address.

Usage: Packets and packetization are the bedrock of digital data communications.

A CableLabs group charged with making interoperable interfaces for practically everything on the IP (Internet Protocol) side of the house: Cable modems, voice multimedia terminal adapters (MTAs), home networking spigots.

In a sense, PacketCable picked up where DOCSIS (Data Over Cable Services Interface Specification) left off, in terms of broadening the IP path for services other than broadband Internet. While DOCSIS continues to mature (a version 3.0 was in the works as this was being written), PacketCable has become the umbrella category for all IP-related services. That list includes voice, interactive games, video conferencing, and general multimedia.

Tactically, PacketCable handles activities such as device interoperability and product compliance. A certification testing program assures that products meet the various PacketCable specifications, and that they interoperate with other PacketCable and DOCSIS-based efforts.

Any device that doesnt require electricity to operate. By contrast, any device described as an “active” does need electricity to run. Examples of passives used in cable broadband systems include taps, splitters, and directional couplers. While passives do not require power, they often pass AC power along, for use by the subsequent active device (an amplifier, for example).

The parts of a digital packet stream that contain information needed by the end user, as opposed to parts of a digital packet stream that contain control information needed by network transportation equipment. To engineers, anything that isn’t payload is counted as “overhead.” Using a postal system analogy, the “payload” is the letter you stick into the envelope. The header information is the destination address.

Usage: The total amount of payload available for a given packet transmission technique requires subtracting the amount of packets used to transmit control and destination information.

“Predictive frame,” meaning a piece of the MPEG-2 method for compressing digital video pictures. Compression works by squeezing a series of video frames (in NTSC, 30 per second; 24/second for movies) by removing any duplicated material from one frame to the next.

The I-frame is the first frame sent, and the reference for frames that follow. Next, the MPEG-2 algorithm compares the I-frame against the following frame, and subtracts the parts that are the same. Then, it transmits the difference information, plus some predictions about what the next frame will hold. For example, a soccer ball moving at a particular rate, and in a particular direction, will likely be moving at the same rate and direction in the next frame.

It is the difference information and the predictive information that constitutes the P-frame.

A seemingly massless, subatomic particle that travels at the speed of light, and is harnessed in lightwave technologies to transport signal-carrying electromagnetic waves. Photons are peppier and sturdier carriers than radio frequency (RF).

Light, and the photon, is a bit of a riddle among really smart people who enjoy musing about such matters. What seasons the discussion is the fact that light exhibits properties of both particles and waves. Generally speaking, this cant be. Yet it is. The part of light that behaves like a wave is what happens when it bends, as thru a prism. Particles don’t bend; waves do. The part of light that behaves like a particle is its responsiveness to strong gravitational forces. Waves don’t respond to gravity; particles do.

It is the wave-like properties of light that matter for moving communications signals. The particle-like properties are generally dismissed.

The bottom-most layer in the OSI (Open System Interconnection) stack, which defines electrical, mechanical and handshaking means for bits moving over a transmission link.

In common cable data parlance, the “PHY” layer (pronounced “fie,” as in “hi-fi”) is almost always uttered in the same breath as “MAC” (Media Access Control). They go together as “MAC and PHY,” (pronounced “mack and fie”) to denote the way packet-based digital data moves down and up the cable system, to connected devices. These days, “connected devices” that land within MAC and PHY sensibilities include cable modems, voice over IP adapters, DSG (DOCSIS set-top gateway) boxes, and anything else needing passage over the IP (Internet Protocol) pipes.

In this context, the “PHY” is the means for modulating bits onto the cable plant — Quadrature amplitude modulation (QAM) in the downstream, headend-to-home direction; a mixture of QAM and Quadrature phase shift key (QPSK) in the upstream. The “MAC” arbitrates available bandwidth among devices (cable modems) which need to share it, particularly in the upstream, home to headend direction. That’s because cable modems share the same RF spectrum as other connected modems on a particular node. In the OSI layering, “MAC” falls in the data-link layer.

The name tag for each segment in a digital video bit stream. Pronounced as a word, as in, rhymes with kid. Everything that moves over MPEG transport has a PID, even packets from cable modems and voice over IP terminals.

Everything used to transmit signals, from the outside of the headend or central office, to the exterior of the connected home or business. This includes, but is not limited to, trunk cable, feeder cable, fiber optic cable. Amplifiers, line extenders, optical nodes. Transmitters, receivers, passive devices. Pole line hardware, strand, clamps. And so on.

The construction of cable plant is capital intensive, costing from $10K to $30K per mile, depending on whether that mile is brand new, under upgrade, or an extension of an existing system. The density of homes per cable mile is also a cost factor, as is the labor required. And, costs vary depending on whether the plant is aerial over underground (underground is more expensive, both in dollars and in community relations; it often involves digging up streets and flowerbeds.

A written accord between the cable and consumer electronics industries, submitted to the Federal Communications Commission in December, 2003, and made into an FCC proceeding nine months later. The initial cable/CE accord produced one-way “digital cable ready” devices — mostly TVs and HDTVs — that came with a slot for a removable security card. By the holiday sales season of 2004, eleven CE manufacturers plied some 140 different TV models onto retail shelves, all of which contained the fruits of the one-way Plug & Play agreement.

The guiding intent, throughout the Plug & Play chapters, is for Customer Jane to wander into a “big box” retail store, buy an HDTV set, take it home, decide she wants pay services, call her cable operator, get a card, slide it in — and bingo, premium pictures and sound.

Early reports on CableCARD devices, culled from home theater enthusiast magazines, were surprisingly positive. Home theater hobbyists especially liked the ability to get all TV channels, even the premiums, without needing a set-top box — or, more importantly, the separate remote control that comes with the set-top box.

The security card itself (happily) got a new name in the process, morphing (with help from the marketing community, through CTAM) from “POD,” for point of deployment module, to “CableCARD.”

In industrial circles, nothing seemed to be as time-hungry as the Plug & Play negotiations. Work continues to hammer out a two-way version of the agreement, so that consumers can access interactive materials. It is vexing work, because so many enormous industrial contingents are involved: Cable and CE, as well as the personal computer/information technologies sector.

The technical name for whats expressed to consumers as “CableCARD.” CableCARD slots are built into digital cable-ready TV and HDTV sets; the cards themselves are provided by individual cable operators when a consumer seeks a scrambled service. PODs, marketed as CableCARDs, are included in all fielded digital boxes installed after July, 2007. That was an FCC requirement, sought to further open the retail floodgates for digital devices.

The ability to take your digital media with you, so that you can watch it, or listen to it, whenever. With portability, the sequence generally requires the media — audio, video, digital photographs — to be downloaded into the handheld player, usually from a personal computer. Conversely, “mobility” implies digital media thats sent to you while youre on the move. MP-3 players are portable; cell phones are mobile. Generally, what’s mobile is almost always portable, but what’s portable isn’t always mobile.

The father of on-demand TV ordering: Customers could order a premium title, but they couldnt yet order it any time they wanted, and they couldn’t yet invoke pause, fast forward, or rewind maneuvers.

PPV is common to analog cable television systems, but starts to look more and more obsolescent with every new digital cable customer.

In PPV, customers are informed about an upcoming event by a televised ad, promoting a program airing at a specific time. Sometimes ordering means picking up the phone; other systems let customers order by pushing a button on the remote control.

Not many analog set-tops were equipped for two-way signaling, to zap the purchase request up the cable plant for receipt at the headend. To remedy that void, a technique called “store-and-forward” was put into play. It worked like this: A subscriber pushed the button on the remote, to order a PPV event. The order was stored in the box, and confirmed locally, through a simple acknowledgement screen housed inside the box. Later, the box was interrogated by a headend device that retrieved and handled the order.

A category of technologies and services that manage inbound and outbound communications, on multiple devices, based on a person’s availability, device capabilities, and preferences. Presence, in a sense, is the “instant: in “instant messaging,” because its what knows when you’re attached to the network, so you can be pinged, live.

Presence, as a technique, strives to be the answer to three questions: Are you on the network? How are you on the network (cell phone? PC? Gadget?) Are you available for communications at this time?

Presence, as a technology, grew from the world of Session Initiation Protocol, or SIP — the underbody of voice services such as Vonage, AT&Ts CallVantage, and Verizons Broadwing.

When it grows up, presence will be like instant messaging and buddy lists — except broader, across more devices, and with more than just text. It’ll do things like finding you, by ringing all your numbers, text messaging all your devices, and IMing you anywhere youre logged in, when it’s someone you really, really, really want to reach, you no matter what — or doing exactly the opposite, when it’s anyone you don’t want to reach you, no matter what.

So far (2005), it’s the latter feature thats working for presence-enabled customers: One of the most popular presence applications is “do not disturb,” which makes people invisible to incoming messages.

An interactive enticement that pops onto the TV screen coincident with, and pertaining to, a show in progress. Synonymous with “bound applications,” which also come along with a TV show or advertisement — rather than being independently invoked from a specific button on the menu or guide. Voting for an American Idol on screen, rather than by dialing the phone, is an example of program synchronous interactivity.

The technology used to display images on PC monitors. Differs from “interlace” scanning, used in TV displays; as such, “progressive scan” is also sometimes referred to as “non-interlace.” Progressive scan works by drawing an image on a screen from top to bottom, one line at a time.

By contrast, interlace techniques paint half the lines representing the image on a first run down the screen, and the other half on a second swipe.

A set of rules that define how two or more pieces of equipment “talk” to each other. Also, a set of rules that define how data is transmitted and received. The word “protocol” usually travels with digital equipment more so than analog gear. A classic example is “Internet Protocol,” or “IP,” which are the rules of the road for moving email, Web requests or files over the public Internet, or over a private, IP backbone.

There are as many protocols as there are types of digital applications. Rules are rules, and are necessary to govern the existence of complex tasks. Generally, though, protocols govern matters such as packet size, how errors are handled, and what to do when a transmission path becomes non-navigable.

To activate a customer or a device for service, as automatically as possible. Provisioning a customer for broadband Internet service, as one example, means super-multi-tasking with the back office: Loading browser software onto a consumers computer; securing and assigning IP (Internet Protocol) addresses; re-directing the cable modem to other equipment that needs it; directing the customer to an account setup screen; linking with billing systems.

When this dictionary was last written (2001), the prevailing prefix for “provisioning” was “self.” Getting to the world of do-it-yourself broadband installs was a pressing goal, in the earliest years of the new century.

This time around (2005), provisioning has a different hot-topic prefix: “Flow-through.” Flow-through provisioning builds software paths through the many databases that make, or break, the “seamless” in new service activation. It means having “transparency” into those databases, so that if something kicks back as “unserviceable,” there’s a way to find out what that means, and how to fix it.

If self-provisioning solved the goal of the do-it-yourselfer, flow-through provisioning moves the goalpost into the software-dense milieu of the back office.

Program and System Information Protocol. Pronounced “pee-sip.” The extra data that accompanies a terrestrial digital television signal: Time, ratings information, identifiers, data that could populate an electronic program guide. PSIP data is interpreted by the chips, inside digital TVs, tasked with over-the-air transmissions. It’s an outgrowth of the extra 6 MHz channel given to broadcasters by the FCC, to begin the “digital transition.” As broadcasters began to formulate usage plans, they realized, as does anyone preparing to move content digitally rather than traditionally, that they’d have a lot of meta data (data that describes other data). PSIP is the terrestrial approach for conveying meta data. Cable and satellite technologists are watchful of PSIP in a Trojan Horse sense. The concern is that applications and content not contained in carriage agreements will be slipped through in PSIP tables, and interpreted by digital TVs.

Any communications network operated by a common carrier, that links a phone or modem from one end business or home to the phone or modem of another business or home, through a switch. In general language, the “PSTN” is synonymous with “telco.”