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In this lesson,

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we're going to cover cable connections,

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often referred to as DOCSIS connections.

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Now, DOCSIS is a prevalent technology these days

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that brings high-speed internet

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into the homes and offices through the same lines

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that deliver your favorite TV shows.

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When you're watching a thrilling movie on cable TV

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and simultaneously browsing the internet,

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little did you realize that these two streams of data

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are actually going over the same exact cable,

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thanks to the wonders of a system known as HFC,

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or the hybrid fiber-coaxial

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and a little known standard called DOCSIS,

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which stands for Data Over Cable Service

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Interface Specification.

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Let's start by taking a look at the backbone

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of this technology,

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which is the hybrid fiber-coaxial network,

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or the HFC network.

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Think about the HFC network as a high-capacity highway

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that smoothly carries vast amounts of data

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using a blend of fiber optic and coaxial cables.

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The fiber optic cables are known

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for their high-speed data transmission capabilities,

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and they can cover longer distances,

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typically from the service provider's facility

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to a distribution point near your home.

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From there, the coaxial cables,

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the same ones used for your cable TV,

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will take over and deliver data

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directly to your home or office.

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This blend ensures a robust

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and efficient delivery of high-volume data,

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and this makes it an ideal solution

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for data-hungry networks at your home or office.

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Now, let's take a look at DOCSIS.

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DOCSIS is a suite of specifications

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that standardizes how data is transmitted

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over a hybrid fiber-coaxial network.

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It ensures that regardless of your location

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or the service provider, your cable modem,

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which is that device that connects your home network

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over to the internet,

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speaks the same language

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as the rest of the cable internet world.

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This standardization is crucial for maintaining consistent,

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reliable, and high-speed internet access.

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Now, DOCSIS specify certain frequency ranges

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for upstream and downstream transmissions,

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which essentially means it designates specific lanes

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for sending data to and from the internet.

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Typically, the upstream,

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or the data you're sending out from your house,

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like your emails and uploaded files,

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will use a range between five and 42 megahertz,

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while your downstream,

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or the data you're receiving,

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like streaming video and website content,

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operates between 50 and 860 megahertz.

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This separation helps in managing traffic efficiently

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and ensures that your request for data

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and the incoming data

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don't collide in a digital traffic jam.

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Now, one of the things you need to note here

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is that when you're dealing with a cable modem,

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they're almost always going to be asynchronous

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in terms of their upload and download speeds.

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What that means is that you're going to expect

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to get very high download speeds,

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but rather slow upload speeds.

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For example, at my current home,

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I only have the option of using a cable modem,

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and when I use that cable modem,

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it's relying on this DOCSIS standard.

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I've paid for one gigabit per second of service,

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which is what I get when I do downloads.

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But when I'm uploading things like this video

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to our servers,

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I'm only able to get around 30 to 40 megabits per second.

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And this goes back to those ranges we just covered.

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When I talked about downloads,

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we talked about going from 50 to 860 megahertz,

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which is 810 megahertz worth of bandwidth.

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But when we talked about the uploads,

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we only talked about between five and 42 megahertz,

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which means we only have 37 megahertz of bandwidth.

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So you can see there's a drastic difference

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between the amount you can download

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and what you can upload when using a cable modem.

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Now, one of the most compelling aspects

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of using cable connections like DOCSIS

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is their use of the existing cable TV infrastructure.

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This infrastructure was already going

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through most of our neighborhoods,

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making the rollout of cable internet really cost effective

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and very quick to do,

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as opposed to having to rewire entire neighborhoods

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for fiber connectivity.

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Now, this means for users that transitioning to

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or adopting cable internet was a really convenient option

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because it offered much higher speeds

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than the thing at the time,

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which was known as DSL,

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or digital subscriber lines,

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that were popular back in the late 1990s and early 2000s

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when cable modes were starting to gain prevalence.

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As the technology evolved, though, so did DOCSIS,

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with several versions improving upon the speed, efficiency,

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and security of the system.

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From DOCSIS 1.0 to the latest versions,

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each iteration has brought enhancements

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that allowed for faster internet speed

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up to one or even five gigabits per second on the downloads,

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better performance,

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and more robust security features

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to ensure that users' data

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was zooming across the network safely and swiftly.

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So remember, if you hear the terms HFC or DOCSIS,

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they're more than just acronyms.

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They are pillars that support much

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of our high-speed internet access today

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when you're using cable modems and cable connections.

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Whether you're streaming high-definition movies,

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attending video conferences,

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or engaging in online gaming,

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if you're using a cable connection, you're relying on DOCSIS

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to ensure your digital experience is speedy and seamless.