Time
31 hours 29 minutes
Difficulty
Beginner
CEU/CPE
30

Video Description

Network Topologies: Bus This lesson covers bus topology. In bus topology, all of the nodes are connected to a single cable. This is very common in set ups when there is a T axle on each node as well as in 10-base-5 networks. In bus topology, all signals are sent using broadcast. An advantage of bus topology is that it has the least cost and set up; it is also good for small networks A disadvantage of bus topology is that it has limited length and if one node goes down, everything goes down.

Video Transcription

00:04
now. Next, we have our bust. Apology. Now, our bust apology is going to be all of our nose connected to a single line, a single main cable. Now, this is very this is very common, especially in our networks, where we have our co axel Arco axel
00:20
with Artie connectors on each of our nodes. And it's also very common in our 10 based five networks. These air gonna be it's gonna in these networks. We're gonna have a single co axial cable that goes along the length of our network. And then each of our nodes is goingto have our tea connector, which we talked about is a single co axel connector into the computer
00:40
with a
00:42
metal
00:43
connector that plugs into the cable. So the cable comes in, sends the signal to our computer and keeps going.
00:51
Now,
00:52
with our bust apology, all of all of our signals are sent using broadcast because we only have one cable that were sitting across. Don't don't confuse our single cable with a cable that goes along stops that each computer goes in and if it's good, it stops or if it's not, it's keeps going.
01:11
Our signal is going to travel down this line
01:15
just like an electrical signal
01:17
and is going to go
01:22
teach in point. It's like an electric. It's just like in an electrical circuit. If you connect in an electrical, why if you have a main electrical wire that goes directly to several light bulbs and there's no and there's no electrical switch on those light bulbs,
01:37
all right, there's no honor off switch on those light bulbs that electrical signals going to go to those light bulbs and keep going
01:45
now
01:46
the down side. One of the downsides of this, which will also which will talk about a second in length, is that if our node at R T connector goes down, then our entire network goes down. But we won't talk about that a little bit more in a second.
02:00
So we have our signal sent using broadcast, and at the end of our cable, we have a Terminator. Now what is the Terminator? D'oh!
02:08
Now, besides traveling through time,
02:12
our terminators also help stopping signals from bouncing back
02:17
now with our the way that our electrical signal is going down our cable length.
02:23
If we did not have a terminator,
02:27
our electrical signal would actually bounce off of the end of that cable, so would hit the end of that cable. There would be nothing that it would go into. And so our electrical signal would bounce back
02:39
and then hit its source and then bounce back and bounce back and bounce back. And this would create collisions on our network and could effectively shut down our network.
02:49
So what a Terminator does is a Terminator
02:57
actually just takes that signal and then just dead ends. It just kills it.
03:00
So it keeps our It keeps our signal from bouncing back the other way. And so we don't wanna have any any loose ends on our cables where we just leave it without a Terminator block. We need to have a Terminator block on our bus networks, especially with our co axel.
03:16
So the good of this network is that
03:20
it's it's the least amount of cost in the least amount of set up, because all we're doing is we're running a single line, and then each of the nodes are connecting into it. So we're only paying for that one main line and then the lines and then the individual,
03:36
the individual T connectors that individual connectors to that main line. It's not a mesh network we have, where we have multiple cables going to multiple nodes, and it's good on smaller networks. Because of that, it's the least amount of setup, least amount of hassle. We just run this. We just run the connection. We run the bus and we connected into the bus and we're good. So we need
03:55
now. The bad of this is that it's a limited length. We've talked about our cable lengths in a previous module, but our bus is really limited by our cable length because if we can only send that signal so far, so so we can't run a single cable length. We can't run a single bus, the route, multiple floors and an entire building.
04:16
Um, so we have a limited length to to this network. Also, additionally, one thing that I mentioned before that if one note is down, our entire network is down. If one note is down, it's just like breaking a circuit in an electrical in an electrical circuit. We break that node
04:34
and the signal can't propagate down through the rest of our network,
04:41
so we still have our cable physically there, but the signal can't keep going, Um, and so our network's going to go down. So we need to know that we need to understand that this does require a lot of, ah lot of management and making sure that we have our make sure that our Kate are nodes Don't go down,
05:00
that they aren't disconnected because that will affect the rest of our network
05:02
now in our bust. Apology.
05:06
One of the things we need to keep in mind is that we do have this broadcast signal that goes down to each of our notes.
05:15
This could be another bad,
05:16
because if note eh
05:19
is trying to send data
05:21
to know D,
05:26
then node C can hear what's going on,
05:29
as can no be
05:30
now. Typically, our computers will if they see that the pack, it's not for them. They'll just discard it.
05:35
They won't they won't really look at it.
05:38
But if say computer, see is running a wire shark and is listening to the packets that are going on in our network, it's going to see everything. That's all the data that's going on our network because everyone's going to hear everything.
05:53
So we do need to be aware that bust apology is going to be a little bit of a security risk because of that fact, because because data isn't being sent just to the node, that it's destined for all data is going to everybody. So if it's in clear text, if it's not an encrypted in an encrypted format,
06:13
then all it takes is a, uh,
06:15
a packet analyzer on a connection to our network, and they'll be able to see what's going on.

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CompTIA Network+

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Anthony Harris
Systems Analyst and Administrator at SAIC
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