0:00:02.080,0:00:03.919
when you're designing building or

0:00:03.919,0:00:05.839
troubleshooting a network you'll be

0:00:05.839,0:00:08.720
using a network topology type that can

0:00:08.720,0:00:10.960
vary depending on the technology you're

0:00:10.960,0:00:13.120
using if you're looking to understand

0:00:13.120,0:00:15.280
the way the data is flowing or you want

0:00:15.280,0:00:18.000
to plan to create a new type of network

0:00:18.000,0:00:19.600
then it's useful to understand what

0:00:19.600,0:00:22.080
these topologies might be this is also

0:00:22.080,0:00:23.439
useful during the troubleshooting

0:00:23.439,0:00:25.680
process because you'll know exactly what

0:00:25.680,0:00:27.920
flow the traffic takes to get between

0:00:27.920,0:00:30.720
point a and point b one of the most

0:00:30.720,0:00:33.440
popular types of topologies is the star

0:00:33.440,0:00:35.200
topology you might also hear this

0:00:35.200,0:00:37.440
referred to as a hub and spoke where the

0:00:37.440,0:00:39.520
hub is in the middle and the spokes are

0:00:39.520,0:00:42.320
along the outside this is a topology

0:00:42.320,0:00:44.480
that you'll find on almost any network

0:00:44.480,0:00:47.120
regardless of the size of the network

0:00:47.120,0:00:49.360
and you'll also find that most devices

0:00:49.360,0:00:51.840
are connecting back to the central hub

0:00:51.840,0:00:54.480
of the star for example a switched

0:00:54.480,0:00:57.039
ethernet network has the ethernet switch

0:00:57.039,0:00:59.680
in the middle of this star and then all

0:00:59.680,0:01:02.960
of the devices run directly back to this

0:01:02.960,0:01:05.040
particular switch they're not connecting

0:01:05.040,0:01:07.119
to each other they're instead connecting

0:01:07.119,0:01:09.360
back to the central switch in this star

0:01:09.360,0:01:11.119
topology

0:01:11.119,0:01:12.960
although we don't often see a ring

0:01:12.960,0:01:16.000
topology used on our local area networks

0:01:16.000,0:01:17.920
it's still a topology type that's used

0:01:17.920,0:01:20.720
quite often for wide area networks so

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although many people will remember the

0:01:22.560,0:01:24.799
older token ring technologies that we

0:01:24.799,0:01:26.880
used to run inside of our local area

0:01:26.880,0:01:29.200
networks we don't generally find those

0:01:29.200,0:01:31.439
ring networks any longer but if you're

0:01:31.439,0:01:33.439
connecting over a metropolitan area

0:01:33.439,0:01:36.320
network or a wide area network we use

0:01:36.320,0:01:38.960
ring networks extensively it's not

0:01:38.960,0:01:41.439
because a ring technology somehow lends

0:01:41.439,0:01:43.600
itself to work better over a wide area

0:01:43.600,0:01:45.680
network it's because we can create

0:01:45.680,0:01:48.159
additional redundancy using the ring

0:01:48.159,0:01:49.520
topology

0:01:49.520,0:01:51.759
for example very common way to send

0:01:51.759,0:01:54.000
traffic over a ring network is to have

0:01:54.000,0:01:56.640
the traffic simply go in a circle now if

0:01:56.640,0:01:58.479
we're on this wide area network and

0:01:58.479,0:02:00.320
there's construction going on and

0:02:00.320,0:02:02.320
someone happens to sever a fiber

0:02:02.320,0:02:04.159
connection that's being used for this

0:02:04.159,0:02:06.640
metropolitan area network then we're not

0:02:06.640,0:02:08.640
going to be able to send that traffic

0:02:08.640,0:02:10.640
through the rest of that ring but the

0:02:10.640,0:02:13.200
devices that are on either side of that

0:02:13.200,0:02:15.680
severed link recognize that traffic is

0:02:15.680,0:02:17.599
no longer able to traverse that

0:02:17.599,0:02:19.840
connection and instead will loop back

0:02:19.840,0:02:22.239
the connection on those individual

0:02:22.239,0:02:24.560
endpoints so instead of having data go

0:02:24.560,0:02:26.879
around a ring the data will instead go

0:02:26.879,0:02:29.440
to as far as it can around the ring and

0:02:29.440,0:02:31.840
then loop back to get to the other side

0:02:31.840,0:02:34.000
of the ring maintaining up time and

0:02:34.000,0:02:36.640
availability even in the case where part

0:02:36.640,0:02:39.519
of that ring may be severed

0:02:39.519,0:02:41.360
early types of ethernet networks were

0:02:41.360,0:02:43.360
not switched ethernet but were instead

0:02:43.360,0:02:46.480
run over coax and this coax was quite

0:02:46.480,0:02:48.879
simply a cable that was run down the

0:02:48.879,0:02:51.440
middle of the room very similar to this

0:02:51.440,0:02:54.239
cable this is a bus network and although

0:02:54.239,0:02:56.080
it was commonly used on those early

0:02:56.080,0:02:58.319
ethernet networks we can still find

0:02:58.319,0:03:00.560
modern networks that use the same bus

0:03:00.560,0:03:01.920
topology

0:03:01.920,0:03:04.400
one problem with bus networks is that it

0:03:04.400,0:03:06.800
is a single cable that is running either

0:03:06.800,0:03:08.879
through the walls or down the center of

0:03:08.879,0:03:11.120
the room and if we happen to have a

0:03:11.120,0:03:13.440
break in this cable you can see

0:03:13.440,0:03:15.599
immediately that it would suddenly

0:03:15.599,0:03:17.519
segment the network into different

0:03:17.519,0:03:20.400
pieces or in some cases cause no data to

0:03:20.400,0:03:22.879
be transferred across the network that's

0:03:22.879,0:03:24.959
one of the reasons we moved away from

0:03:24.959,0:03:27.680
bus networks for our local area networks

0:03:27.680,0:03:29.760
because one single disconnect could

0:03:29.760,0:03:32.000
cause an outage for everybody else on

0:03:32.000,0:03:33.280
the network

0:03:33.280,0:03:35.680
in our modern automobiles we have bus

0:03:35.680,0:03:37.680
networks that we use extensively these

0:03:37.680,0:03:41.280
are controller area network buses or can

0:03:41.280,0:03:43.200
bus connections and they're used to

0:03:43.200,0:03:45.200
connect all of the different sensors and

0:03:45.200,0:03:47.760
controllers inside of our automobiles to

0:03:47.760,0:03:49.840
be able to make all of our cars much

0:03:49.840,0:03:52.480
safer to drive on the roads

0:03:52.480,0:03:54.640
another popular topology especially in

0:03:54.640,0:03:57.040
larger networks is to create a mesh

0:03:57.040,0:04:00.319
between devices or a mesh between sites

0:04:00.319,0:04:02.480
we may have devices that are connected

0:04:02.480,0:04:04.720
in different locations and we might want

0:04:04.720,0:04:06.480
to connect them all together but instead

0:04:06.480,0:04:08.480
of having a single connection to a

0:04:08.480,0:04:10.720
particular site we may want to create

0:04:10.720,0:04:12.799
multiple connections to mesh these

0:04:12.799,0:04:15.760
together that way if we do lose any one

0:04:15.760,0:04:17.840
of these network links we're able to

0:04:17.840,0:04:20.320
work around that problem by simply using

0:04:20.320,0:04:22.800
one of the redundant connections

0:04:22.800,0:04:25.040
you'll commonly use this type of mesh

0:04:25.040,0:04:26.960
design if you're creating redundancy or

0:04:26.960,0:04:28.800
fault tolerance or perhaps you're

0:04:28.800,0:04:30.800
designing a load balance network and you

0:04:30.800,0:04:32.479
can use different parts of the network

0:04:32.479,0:04:34.000
to share that load

0:04:34.000,0:04:36.479
probably the most common place to find a

0:04:36.479,0:04:38.960
wired mesh network is over a wide area

0:04:38.960,0:04:41.120
network where you can create multiple

0:04:41.120,0:04:43.040
links to other sites so that you can

0:04:43.040,0:04:45.120
have a primary connection from one site

0:04:45.120,0:04:47.040
to the other and then a backup or

0:04:47.040,0:04:49.120
secondary connection that you can use if

0:04:49.120,0:04:51.440
you run into problems

0:04:51.440,0:04:53.040
when you start combining these different

0:04:53.040,0:04:55.440
topologies together you create a hybrid

0:04:55.440,0:04:58.000
network a hybrid network is more than

0:04:58.000,0:05:00.320
one of these topology types all working

0:05:00.320,0:05:02.320
together for example you might have

0:05:02.320,0:05:04.240
three remote sites all connecting

0:05:04.240,0:05:06.320
devices together using a switched

0:05:06.320,0:05:08.720
ethernet or star network and then you

0:05:08.720,0:05:10.639
may be connecting those together over a

0:05:10.639,0:05:12.960
wide area network that uses a ring

0:05:12.960,0:05:14.880
topology

0:05:14.880,0:05:16.560
if you're using a wireless network you

0:05:16.560,0:05:18.560
may be communicating in a number of

0:05:18.560,0:05:20.880
different ways if you're using an access

0:05:20.880,0:05:22.880
point you're probably communicating over

0:05:22.880,0:05:25.280
an infrastructure connection this means

0:05:25.280,0:05:27.039
that all of the devices on your network

0:05:27.039,0:05:29.039
are communicating through an access

0:05:29.039,0:05:31.199
point this is probably the most common

0:05:31.199,0:05:33.600
way to use wireless connections but it's

0:05:33.600,0:05:35.840
not the only way to communicate over a

0:05:35.840,0:05:37.759
wireless link if you just have two

0:05:37.759,0:05:40.000
devices and there's no access point that

0:05:40.000,0:05:42.240
you can use you can connect directly

0:05:42.240,0:05:45.280
from one device to another using ad hoc

0:05:45.280,0:05:47.520
networking you don't need an access

0:05:47.520,0:05:49.520
point or any other type of wireless

0:05:49.520,0:05:51.440
infrastructure you simply have one

0:05:51.440,0:05:53.759
device communicate directly to another

0:05:53.759,0:05:56.639
device over this wireless connection

0:05:56.639,0:05:58.800
and if you've added internet of things

0:05:58.800,0:06:01.120
devices which are commonly wireless

0:06:01.120,0:06:03.680
devices that control our lights our door

0:06:03.680,0:06:06.080
locks or the air conditioning systems

0:06:06.080,0:06:08.000
then you're probably using a mesh

0:06:08.000,0:06:10.400
network where all of these devices can

0:06:10.400,0:06:12.639
communicate to all the other devices

0:06:12.639,0:06:14.960
simultaneously to create an

0:06:14.960,0:06:17.680
interconnected mesh of communication

0:06:17.680,0:06:21.120
between all of these iot devices

0:06:21.120,0:06:23.039
one of the advantages of these mesh

0:06:23.039,0:06:25.840
wireless networks is that it allows many

0:06:25.840,0:06:28.080
devices to communicate to each other

0:06:28.080,0:06:30.560
even if those devices are very far apart

0:06:30.560,0:06:32.720
from each other this also allows the

0:06:32.720,0:06:35.440
mesh network to self-heal so if you turn

0:06:35.440,0:06:37.680
off one of those iot devices the

0:06:37.680,0:06:40.000
remaining devices will self-heal and

0:06:40.000,0:06:42.880
redesign themselves into a mesh network

0:06:42.880,0:06:44.800
that will allow them to continue the

0:06:44.800,0:06:47.800
communication

0:06:57.440,0:06:59.520
you