Network Connectivity
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Video Transcription
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>> Now, as we mentioned earlier,
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when we have a network,
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we have a group of interconnected devices.
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How do we connect those devices?
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We connect them through media and through
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specific devices designed to connect computers.
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Hubs are what we used to use
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very commonly back in the day,
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simply for the fact that they were cheap.
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But hubs introduced problems and
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some security vulnerabilities into the network,
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so we moved from hubs to switches.
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Switches give us greater control of traffic,
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and switches, in a lot of ways,
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act like a police officer of a busy intersection;
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directing traffic from one path to another.
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Switches will allow you to manage
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traffic on your network more efficiently.
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Routers are primarily about
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connecting to different networks.
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If I want to connect to the Internet,
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I usually do so through a router.
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If I want to connect to my branch in Minnesota,
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usually I connect to an
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external network through my router.
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VLANs are going to give us
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benefits of both switches and routers.
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A VLAN is going to be a virtual LAN,
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so we'll be able to segment
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our network into different subnets,
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if you will, and we can do so on a switch.
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We'll talk about why that's desirable later.
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Then of course, we have to consider
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wireless access and wireless access points,
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and how we'll allow these hosts to
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connect without being physically wired in.
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Another thing to consider is VPN servers,
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and with wireless and VPN,
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we'll talk about those ideas when we get to
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the remote access section.
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Every one of these terms we'll go into more deeply.
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The next thing we have to have if we're going to
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allow communication is a protocol.
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A protocol is really important because you could
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think of this as the language that computers speak,
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and we have to speak the same language.
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Quite honestly, that's not
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the best definition you're going to hear.
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But it is a good way to think about it
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because if I'm speaking
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Greek and you're speaking Spanish,
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we're not going to be able to communicate
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unless we have a translator.
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The more translators we have,
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the more unreliable the communication is.
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If you ever want to do something fun,
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use Google Translate to speak
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a phrase and translate it into Spanish,
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then take that Spanish phrase
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and translate it back to English,
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then take that result and translate it back to Spanish.
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Do that about 10 times and you'll
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find the end result is hysterical.
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By the end, you don't have
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anything you were originally communicating.
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That's the problem when it comes to protocols.
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When you have too many different protocols,
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even though we can get a conversion
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and can get a device called a gateway,
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that's a protocol converter,
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we don't get good true communication.
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What we like to be doing is to
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>> all use the same protocol.
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>> A better definition of a protocol is that it's
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the set of rules or requirements
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that govern communication.
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Things like how much data can be sent at once,
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how do I know if I'm sending
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more data than you can receive,
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how long should data exist on the network,
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and how should the packets be formatted,
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are all examples of information
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>> that make up a protocol.
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>> But again, from this stand point,
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you can think of it as a language.
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We have to share the language.
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The most common protocol we have and use by
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far is the TCP/IP protocol.
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It's actually not a protocol.
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It's called a protocol stack or suite.
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It's called a protocol stack because it's
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made up of a lot of little protocols.
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As a matter of fact, you already know two of
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these protocols, TCP and IP.
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There's also HTTP, UDP, ICMP, LMNOP it feels like.
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>> There are a lot of
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>> protocols that make up the TCP/IP suite.
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Each of them have a particular purpose.
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Just like everything, we're going to go
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over this in more depth later.
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The medium, cable or the airwaves.
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With cable, there are
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three main types that we use for networking;
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coaxial, twisted pair,
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and fiber optic cable.
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Each of these are in use today,
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and they each have their place.
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We'll cover this in another chapter where we get into
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more details and specifics of mediums.
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We have to have cable or airwaves if we're going to
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traverse because we need that path for data to travel.
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Ultimately, what we talked about
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here is the fact that there are a lot of elements
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that have to come together
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if we're going to be able to share
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resources and communicate across the network.
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At the very basic level,
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we have the systems we want to connect.
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Then if we want a domain environment,
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we have to have a network operating system.
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That creates the domain or the realm.
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We use connectivity devices and protocols,
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that way we can agree on how to communicate.
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Of course, there is media,
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which is what we traverse.
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Also mentioned here,
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we have certain network services that we
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utilize like DNS and DHCP.
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