All language subtitles for 18. What is half duplex and full duplex

Even if it was running at only 10 Mbps

provides a full 10 Mbps to the PC connected to the port.

In other words PC A gets a full 10 Mbps

rather than sharing that bandwidth with other devices.

That�s very different to the 0.75 Mbps we had when we were using a hub.

10 Mbps is dedicated on individual ports rather than being shared between devices.

So if you add more devices on the switch

it doesn�t degrade the throughput that each device gets.

In addition you can increase the speed by changing the duplex.
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So by setting this to full duplex you actually get 20 Mbps
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hubs operated by using CSMA/CD which is very similar to 10base2.
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with shared bandwidth they are collisions whereas
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with a switch when full duplex is enabled it means that you can send
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and receive traffic at the same time.
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Half duplex communication is like a walky talky
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where only one side can send at any given time.
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So one party would say "Hello! How are you?" over
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and over is used to indicate to the other party that they can speak.
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The other party would then say something and end with the word over.
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So that the first party could say something.
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The moral of the story is that only one party can transmit at any given time
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if both parties try to transmit at the same time,
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there�ll be a collision that�s half duplex.
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Full duplex communication on the other hand is like a landline telephone
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where you can speak and listen at the same time.
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Landline telephones use full duplex so both parties can speak
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and listen simultaneously whereas walkie talkies are half duplex devices
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where one party can transmit and the other party needs to receive.
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Walkie talkies only one person can speak at a time
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landline telephones both parties can speak at the same time.
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Walkie talkies as an analogy are half duplex, landline telephones are full duplex.
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Hubs once again use Carrier Sense Multiple Accesses Collision Detection
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in other words half duplex where only one party can transmit at any given time.
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An individual port on a switch however, you can set those ports to use full duplex
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which means that both the switch and the PC
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can transmit and receive at the same time.
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Just be aware however that when you enable full duplex,
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collision detection is turned off because the devices operate on that premise
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that they can send and receive at the same time.
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So there�s no need to have collision detection because no collections will take place.
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That will cause issues however where 1 side is set to full duplex
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and the other side is set to half duplex.
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It is important that full duplex be enabled on both sides
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if you wanna use full duplex.
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But once again in this example if full duplex is enabled
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rather than only having 10 Mbps in theory you can increase that to 20 Mbps
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because both parties can transmit and receive at the same time.
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So by just replacing a hub with a switch
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we can increase the throughput of of this network from 0.75 Mbps to 20 Mbps
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all we did was replace the hub with the switch and enabled full duplex.
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Now full duplex is often negotiated automatically between devices.
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So the switch and the PC will negotiate to use full duplex
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if they both support it and will hopefully choose correctly.
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In networks it does happen that 1 side chooses full duplex
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and the other side chooses half duplex.
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And that�s gonna cause a lot of problems on that link.
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So if users complaining about slow throughput
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check the duplex on both sides and check that it�s been negotiated correctly
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because it may have negotiated incorrectly.
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Speed by the same token can also negotiated between a switch in a PC
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and that could also be incorrectly negotiated.
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These days PCs tends to have gig ports
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and thus the bandwidth can increase
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from 0.75 Mbps when using a hub to 2 gigabits per second
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The throughput of switches is much, much greater than hubs
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and therefore switches are preferred today
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over other devices like hubs or bridges.
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Be aware however that in wireless networks
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access points tend to operate like hubs
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which have a shared infrastructure which therefore means
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shared bandwidth where as with switches devices have dedicated bandwidth.
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So in summary a switches a layer 2 device in the OSI model
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it operates at the data link layer.
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Switches have major advantages when compared with hubs
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and bridges and that�s to do with the throughput
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and scalability of networks using switches.
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Switches process frames in hardware rather than in software
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and can therefore process frames at wire speed
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as well as supporting many more ports than bridges and hubs.
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These days switches can also operated layer 3, hence the term layer 3 switches.
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But for the moment we're just talking about pure layer 2 switches.
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We'll know discuss routers and then we can talk about layer 3 switches.