[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:02.08,0:00:03.92,Default,,0000,0000,0000,,When you're designing, building, or
Dialogue: 0,0:00:03.92,0:00:05.84,Default,,0000,0000,0000,,troubleshooting a network, you'll be
Dialogue: 0,0:00:05.84,0:00:08.72,Default,,0000,0000,0000,,using a network topology type that can
Dialogue: 0,0:00:08.72,0:00:10.96,Default,,0000,0000,0000,,vary depending on the technology you're
Dialogue: 0,0:00:10.96,0:00:13.12,Default,,0000,0000,0000,,using. If you're looking to understand
Dialogue: 0,0:00:13.12,0:00:15.28,Default,,0000,0000,0000,,the way the data is flowing, or you want
Dialogue: 0,0:00:15.28,0:00:18.00,Default,,0000,0000,0000,,to plan to create a new type of network,
Dialogue: 0,0:00:18.00,0:00:19.60,Default,,0000,0000,0000,,then it's useful to understand what
Dialogue: 0,0:00:19.60,0:00:22.08,Default,,0000,0000,0000,,these topologies might be. This is also
Dialogue: 0,0:00:22.08,0:00:23.44,Default,,0000,0000,0000,,useful during the troubleshooting
Dialogue: 0,0:00:23.44,0:00:25.68,Default,,0000,0000,0000,,process because you'll know exactly what
Dialogue: 0,0:00:25.68,0:00:27.92,Default,,0000,0000,0000,,flow the traffic takes to get between
Dialogue: 0,0:00:27.92,0:00:30.72,Default,,0000,0000,0000,,point A and point B. One of the most
Dialogue: 0,0:00:30.72,0:00:33.44,Default,,0000,0000,0000,,popular types of topologies is the star
Dialogue: 0,0:00:33.44,0:00:35.20,Default,,0000,0000,0000,,topology. You might also hear this
Dialogue: 0,0:00:35.20,0:00:37.44,Default,,0000,0000,0000,,referred to as a hub and spoke, where the
Dialogue: 0,0:00:37.44,0:00:39.52,Default,,0000,0000,0000,,hub is in the middle and the spokes are
Dialogue: 0,0:00:39.52,0:00:42.32,Default,,0000,0000,0000,,along the outside. This is a topology
Dialogue: 0,0:00:42.32,0:00:44.48,Default,,0000,0000,0000,,that you'll find on almost any network,
Dialogue: 0,0:00:44.48,0:00:47.12,Default,,0000,0000,0000,,regardless of the size of the network.
Dialogue: 0,0:00:47.12,0:00:49.36,Default,,0000,0000,0000,,And you'll also find that most devices
Dialogue: 0,0:00:49.36,0:00:51.84,Default,,0000,0000,0000,,are connecting back to this central hub
Dialogue: 0,0:00:51.84,0:00:54.48,Default,,0000,0000,0000,,of the star. For example, a switched
Dialogue: 0,0:00:54.48,0:00:57.04,Default,,0000,0000,0000,,Ethernet network has the Ethernet switch
Dialogue: 0,0:00:57.04,0:00:59.68,Default,,0000,0000,0000,,in the middle of this star. And then all
Dialogue: 0,0:00:59.68,0:01:02.96,Default,,0000,0000,0000,,of the devices run directly back to this
Dialogue: 0,0:01:02.96,0:01:05.04,Default,,0000,0000,0000,,particular switch. They're not connecting
Dialogue: 0,0:01:05.04,0:01:07.12,Default,,0000,0000,0000,,to each other. They're instead connecting
Dialogue: 0,0:01:07.12,0:01:09.36,Default,,0000,0000,0000,,back to the central switch in this star
Dialogue: 0,0:01:09.36,0:01:11.12,Default,,0000,0000,0000,,topology.
Dialogue: 0,0:01:11.12,0:01:12.96,Default,,0000,0000,0000,,Although we don't often see a ring
Dialogue: 0,0:01:12.96,0:01:16.00,Default,,0000,0000,0000,,topology used on our local area networks,
Dialogue: 0,0:01:16.00,0:01:17.92,Default,,0000,0000,0000,,it's still a topology type that's used
Dialogue: 0,0:01:17.92,0:01:20.72,Default,,0000,0000,0000,,quite often for wide area networks. So
Dialogue: 0,0:01:20.72,0:01:22.56,Default,,0000,0000,0000,,although many people will remember the
Dialogue: 0,0:01:22.56,0:01:24.80,Default,,0000,0000,0000,,older Token Ring technologies that we
Dialogue: 0,0:01:24.80,0:01:26.88,Default,,0000,0000,0000,,used to run inside of our local area
Dialogue: 0,0:01:26.88,0:01:29.20,Default,,0000,0000,0000,,networks, we don't generally find those
Dialogue: 0,0:01:29.20,0:01:31.44,Default,,0000,0000,0000,,ring networks any longer. But if you're
Dialogue: 0,0:01:31.44,0:01:33.44,Default,,0000,0000,0000,,connecting over a metropolitan area
Dialogue: 0,0:01:33.44,0:01:36.32,Default,,0000,0000,0000,,network or a wide area network, we use
Dialogue: 0,0:01:36.32,0:01:38.96,Default,,0000,0000,0000,,ring networks extensively. It's not
Dialogue: 0,0:01:38.96,0:01:41.44,Default,,0000,0000,0000,,because a ring technology somehow lends
Dialogue: 0,0:01:41.44,0:01:43.60,Default,,0000,0000,0000,,itself to work better over a wide area
Dialogue: 0,0:01:43.60,0:01:45.68,Default,,0000,0000,0000,,network. It's because we can create
Dialogue: 0,0:01:45.68,0:01:48.16,Default,,0000,0000,0000,,additional redundancy using the ring
Dialogue: 0,0:01:48.16,0:01:49.52,Default,,0000,0000,0000,,topology.
Dialogue: 0,0:01:49.52,0:01:51.76,Default,,0000,0000,0000,,For example, a very common way to send
Dialogue: 0,0:01:51.76,0:01:54.00,Default,,0000,0000,0000,,traffic over a ring network is to have
Dialogue: 0,0:01:54.00,0:01:56.64,Default,,0000,0000,0000,,the traffic simply go in a circle. Now, if
Dialogue: 0,0:01:56.64,0:01:58.48,Default,,0000,0000,0000,,we're on this wide area network and
Dialogue: 0,0:01:58.48,0:02:00.32,Default,,0000,0000,0000,,there's construction going on and
Dialogue: 0,0:02:00.32,0:02:02.32,Default,,0000,0000,0000,,someone happens to sever a fiber
Dialogue: 0,0:02:02.32,0:02:04.16,Default,,0000,0000,0000,,connection that's being used for this
Dialogue: 0,0:02:04.16,0:02:06.64,Default,,0000,0000,0000,,metropolitan area network, then we're not
Dialogue: 0,0:02:06.64,0:02:08.64,Default,,0000,0000,0000,,going to be able to send that traffic
Dialogue: 0,0:02:08.64,0:02:10.64,Default,,0000,0000,0000,,through the rest of that ring. But the
Dialogue: 0,0:02:10.64,0:02:13.20,Default,,0000,0000,0000,,devices that are on either side of that
Dialogue: 0,0:02:13.20,0:02:15.68,Default,,0000,0000,0000,,severed link recognize that traffic is
Dialogue: 0,0:02:15.68,0:02:17.60,Default,,0000,0000,0000,,no longer able to traverse that
Dialogue: 0,0:02:17.60,0:02:19.84,Default,,0000,0000,0000,,connection, and instead will loop back
Dialogue: 0,0:02:19.84,0:02:22.24,Default,,0000,0000,0000,,the connection on those individual
Dialogue: 0,0:02:22.24,0:02:24.56,Default,,0000,0000,0000,,endpoints. So instead of having data go
Dialogue: 0,0:02:24.56,0:02:26.88,Default,,0000,0000,0000,,around a ring, the data will instead go
Dialogue: 0,0:02:26.88,0:02:29.44,Default,,0000,0000,0000,,as far as it can around the ring and
Dialogue: 0,0:02:29.44,0:02:31.84,Default,,0000,0000,0000,,then loop back to get to the other side
Dialogue: 0,0:02:31.84,0:02:34.00,Default,,0000,0000,0000,,of the ring, maintaining uptime and
Dialogue: 0,0:02:34.00,0:02:36.64,Default,,0000,0000,0000,,availability even in the case where part
Dialogue: 0,0:02:36.64,0:02:39.52,Default,,0000,0000,0000,,of that ring may be severed.
Dialogue: 0,0:02:39.52,0:02:41.36,Default,,0000,0000,0000,,Early types of Ethernet networks were
Dialogue: 0,0:02:41.36,0:02:43.36,Default,,0000,0000,0000,,not switched Ethernet, but were instead
Dialogue: 0,0:02:43.36,0:02:46.48,Default,,0000,0000,0000,,run over coax. And this coax was quite
Dialogue: 0,0:02:46.48,0:02:48.88,Default,,0000,0000,0000,,simply a cable that was run down the
Dialogue: 0,0:02:48.88,0:02:51.44,Default,,0000,0000,0000,,middle of the room, very similar to this
Dialogue: 0,0:02:51.44,0:02:54.24,Default,,0000,0000,0000,,cable. This is a bus network. And although
Dialogue: 0,0:02:54.24,0:02:56.08,Default,,0000,0000,0000,,it was commonly used on those early
Dialogue: 0,0:02:56.08,0:02:58.32,Default,,0000,0000,0000,,Ethernet networks, we can still find
Dialogue: 0,0:02:58.32,0:03:01.92,Default,,0000,0000,0000,,modern networks that use the same bus topology.
Dialogue: 0,0:03:01.92,0:03:04.40,Default,,0000,0000,0000,,One problem with bus networks is that it
Dialogue: 0,0:03:04.40,0:03:06.80,Default,,0000,0000,0000,,is a single cable that is running either
Dialogue: 0,0:03:06.80,0:03:08.88,Default,,0000,0000,0000,,through the walls or down the center of
Dialogue: 0,0:03:08.88,0:03:11.12,Default,,0000,0000,0000,,the room. And if we happen to have a
Dialogue: 0,0:03:11.12,0:03:13.44,Default,,0000,0000,0000,,break in this cable, you can see
Dialogue: 0,0:03:13.44,0:03:15.60,Default,,0000,0000,0000,,immediately that it would suddenly
Dialogue: 0,0:03:15.60,0:03:17.52,Default,,0000,0000,0000,,segment the network into different
Dialogue: 0,0:03:17.52,0:03:20.40,Default,,0000,0000,0000,,pieces, or in some cases, cause no data to
Dialogue: 0,0:03:20.40,0:03:22.88,Default,,0000,0000,0000,,be transferred across the network. That's
Dialogue: 0,0:03:22.88,0:03:24.96,Default,,0000,0000,0000,,one of the reasons we moved away from
Dialogue: 0,0:03:24.96,0:03:27.68,Default,,0000,0000,0000,,bus networks for our local area networks--
Dialogue: 0,0:03:27.68,0:03:29.76,Default,,0000,0000,0000,,because one single disconnect could
Dialogue: 0,0:03:29.76,0:03:33.28,Default,,0000,0000,0000,,cause an outage for everybody else on the network.
Dialogue: 0,0:03:33.28,0:03:35.68,Default,,0000,0000,0000,,In our modern automobiles, we have bus
Dialogue: 0,0:03:35.68,0:03:37.68,Default,,0000,0000,0000,,networks that we use extensively. These
Dialogue: 0,0:03:37.68,0:03:41.28,Default,,0000,0000,0000,,are Controller Area Network buses, or CAN
Dialogue: 0,0:03:41.28,0:03:43.20,Default,,0000,0000,0000,,bus connections, and they're used to
Dialogue: 0,0:03:43.20,0:03:45.20,Default,,0000,0000,0000,,connect all of the different sensors and
Dialogue: 0,0:03:45.20,0:03:47.76,Default,,0000,0000,0000,,controllers inside of our automobiles to
Dialogue: 0,0:03:47.76,0:03:49.84,Default,,0000,0000,0000,,be able to make all of our cars much
Dialogue: 0,0:03:49.84,0:03:52.48,Default,,0000,0000,0000,,safer to drive on the roads.
Dialogue: 0,0:03:52.48,0:03:54.64,Default,,0000,0000,0000,,Another popular topology, especially in
Dialogue: 0,0:03:54.64,0:03:57.04,Default,,0000,0000,0000,,larger networks, is to create a mesh
Dialogue: 0,0:03:57.04,0:04:00.32,Default,,0000,0000,0000,,between devices or a mesh between sites.
Dialogue: 0,0:04:00.32,0:04:02.48,Default,,0000,0000,0000,,We may have devices that are connected
Dialogue: 0,0:04:02.48,0:04:04.72,Default,,0000,0000,0000,,in different locations, and we might want
Dialogue: 0,0:04:04.72,0:04:06.48,Default,,0000,0000,0000,,to connect them all together. But instead
Dialogue: 0,0:04:06.48,0:04:08.48,Default,,0000,0000,0000,,of having a single connection to a
Dialogue: 0,0:04:08.48,0:04:10.72,Default,,0000,0000,0000,,particular site, we may want to create
Dialogue: 0,0:04:10.72,0:04:12.80,Default,,0000,0000,0000,,multiple connections to mesh these
Dialogue: 0,0:04:12.80,0:04:15.76,Default,,0000,0000,0000,,together. That way, if we do lose any one
Dialogue: 0,0:04:15.76,0:04:17.84,Default,,0000,0000,0000,,of these network links, we're able to
Dialogue: 0,0:04:17.84,0:04:20.32,Default,,0000,0000,0000,,work around that problem by simply using
Dialogue: 0,0:04:20.32,0:04:22.80,Default,,0000,0000,0000,,one of the redundant connections.
Dialogue: 0,0:04:22.80,0:04:25.04,Default,,0000,0000,0000,,You'll commonly use this type of mesh
Dialogue: 0,0:04:25.04,0:04:26.96,Default,,0000,0000,0000,,design if you're creating redundancy or
Dialogue: 0,0:04:26.96,0:04:28.80,Default,,0000,0000,0000,,fault tolerance, or perhaps you're
Dialogue: 0,0:04:28.80,0:04:30.80,Default,,0000,0000,0000,,designing a load-balanced network and you
Dialogue: 0,0:04:30.80,0:04:32.48,Default,,0000,0000,0000,,can use different parts of the network
Dialogue: 0,0:04:32.48,0:04:34.00,Default,,0000,0000,0000,,to share that load.
Dialogue: 0,0:04:34.00,0:04:36.48,Default,,0000,0000,0000,,Probably the most common place to find a
Dialogue: 0,0:04:36.48,0:04:38.96,Default,,0000,0000,0000,,wired mesh network is over a wide area
Dialogue: 0,0:04:38.96,0:04:41.12,Default,,0000,0000,0000,,network, where you can create multiple
Dialogue: 0,0:04:41.12,0:04:43.04,Default,,0000,0000,0000,,links to other sites so that you can
Dialogue: 0,0:04:43.04,0:04:45.12,Default,,0000,0000,0000,,have a primary connection from one site
Dialogue: 0,0:04:45.12,0:04:47.04,Default,,0000,0000,0000,,to the other, and then a backup or
Dialogue: 0,0:04:47.04,0:04:49.12,Default,,0000,0000,0000,,secondary connection that you can use if
Dialogue: 0,0:04:49.12,0:04:51.44,Default,,0000,0000,0000,,you run into problems.
Dialogue: 0,0:04:51.44,0:04:53.04,Default,,0000,0000,0000,,When you start combining these different
Dialogue: 0,0:04:53.04,0:04:55.44,Default,,0000,0000,0000,,topologies together, you create a hybrid
Dialogue: 0,0:04:55.44,0:04:58.00,Default,,0000,0000,0000,,network. A hybrid network is more than
Dialogue: 0,0:04:58.00,0:05:00.32,Default,,0000,0000,0000,,one of these topology types all working
Dialogue: 0,0:05:00.32,0:05:02.32,Default,,0000,0000,0000,,together. For example, you might have
Dialogue: 0,0:05:02.32,0:05:04.24,Default,,0000,0000,0000,,three remote sites all connecting
Dialogue: 0,0:05:04.24,0:05:06.32,Default,,0000,0000,0000,,devices together using a switched
Dialogue: 0,0:05:06.32,0:05:08.72,Default,,0000,0000,0000,,Ethernet or star network. And then you
Dialogue: 0,0:05:08.72,0:05:10.64,Default,,0000,0000,0000,,may be connecting those together over a
Dialogue: 0,0:05:10.64,0:05:14.88,Default,,0000,0000,0000,,wide area network that uses a ring topology.
Dialogue: 0,0:05:14.88,0:05:16.56,Default,,0000,0000,0000,,If you're using a wireless network, you
Dialogue: 0,0:05:16.56,0:05:18.56,Default,,0000,0000,0000,,may be communicating in a number of
Dialogue: 0,0:05:18.56,0:05:20.88,Default,,0000,0000,0000,,different ways. If you're using an access
Dialogue: 0,0:05:20.88,0:05:22.88,Default,,0000,0000,0000,,point, you're probably communicating over
Dialogue: 0,0:05:22.88,0:05:25.28,Default,,0000,0000,0000,,an infrastructure connection. This means
Dialogue: 0,0:05:25.28,0:05:27.04,Default,,0000,0000,0000,,that all of the devices on your network
Dialogue: 0,0:05:27.04,0:05:29.04,Default,,0000,0000,0000,,are communicating through an access
Dialogue: 0,0:05:29.04,0:05:31.20,Default,,0000,0000,0000,,point. This is probably the most common
Dialogue: 0,0:05:31.20,0:05:33.60,Default,,0000,0000,0000,,way to use wireless connections, but it's
Dialogue: 0,0:05:33.60,0:05:35.84,Default,,0000,0000,0000,,not the only way to communicate over a
Dialogue: 0,0:05:35.84,0:05:37.76,Default,,0000,0000,0000,,wireless link. If you just have two
Dialogue: 0,0:05:37.76,0:05:40.00,Default,,0000,0000,0000,,devices and there's no access point that
Dialogue: 0,0:05:40.00,0:05:42.24,Default,,0000,0000,0000,,you can use, you can connect directly
Dialogue: 0,0:05:42.24,0:05:45.28,Default,,0000,0000,0000,,from one device to another using ad hoc
Dialogue: 0,0:05:45.28,0:05:47.52,Default,,0000,0000,0000,,networking. You don't need an access
Dialogue: 0,0:05:47.52,0:05:49.52,Default,,0000,0000,0000,,point or any other type of wireless
Dialogue: 0,0:05:49.52,0:05:51.44,Default,,0000,0000,0000,,infrastructure. You simply have
Dialogue: 0,0:05:51.44,0:05:53.76,Default,,0000,0000,0000,,one device communicate directly to another
Dialogue: 0,0:05:53.76,0:05:56.64,Default,,0000,0000,0000,,device over this wireless connection.
Dialogue: 0,0:05:56.64,0:05:58.80,Default,,0000,0000,0000,,And if you've added Internet of Things
Dialogue: 0,0:05:58.80,0:06:01.12,Default,,0000,0000,0000,,devices, which are commonly wireless
Dialogue: 0,0:06:01.12,0:06:03.68,Default,,0000,0000,0000,,devices that control our lights, our door
Dialogue: 0,0:06:03.68,0:06:06.08,Default,,0000,0000,0000,,locks, or the air conditioning systems,
Dialogue: 0,0:06:06.08,0:06:08.00,Default,,0000,0000,0000,,then you're probably using a mesh
Dialogue: 0,0:06:08.00,0:06:10.40,Default,,0000,0000,0000,,network where all of these devices can
Dialogue: 0,0:06:10.40,0:06:12.64,Default,,0000,0000,0000,,communicate to all the other devices
Dialogue: 0,0:06:12.64,0:06:14.96,Default,,0000,0000,0000,,simultaneously to create an
Dialogue: 0,0:06:14.96,0:06:17.68,Default,,0000,0000,0000,,interconnected mesh of communication
Dialogue: 0,0:06:17.68,0:06:21.12,Default,,0000,0000,0000,,between all of these IoT devices.
Dialogue: 0,0:06:21.12,0:06:23.04,Default,,0000,0000,0000,,One of the advantages of these mesh
Dialogue: 0,0:06:23.04,0:06:25.84,Default,,0000,0000,0000,,wireless networks is that it allows many
Dialogue: 0,0:06:25.84,0:06:28.08,Default,,0000,0000,0000,,devices to communicate to each other,
Dialogue: 0,0:06:28.08,0:06:30.56,Default,,0000,0000,0000,,even if those devices are very far apart
Dialogue: 0,0:06:30.56,0:06:32.72,Default,,0000,0000,0000,,from each other. This also allows the
Dialogue: 0,0:06:32.72,0:06:35.44,Default,,0000,0000,0000,,mesh network to self-heal. So if you turn
Dialogue: 0,0:06:35.44,0:06:37.68,Default,,0000,0000,0000,,off one of those IoT devices, the
Dialogue: 0,0:06:37.68,0:06:40.00,Default,,0000,0000,0000,,remaining devices will self-heal and
Dialogue: 0,0:06:40.00,0:06:42.88,Default,,0000,0000,0000,,redesign themselves into a mesh network
Dialogue: 0,0:06:42.88,0:06:46.31,Default,,0000,0000,0000,,that will allow them to continue the communication.