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In a later video I'll show you a why shock capture showing you what the traffic or frames looked like

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when sent between two sites.

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But for the moment the high level picture is as follows a P.S. In one local area network is sending

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traffic to a P.C. and another local area network.

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When the traffic is sent across the land and in this case we're using ethernet the IP packet is encapsulated

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in an Ethernet frame so add a layer to the encapsulation used is Ethernet so as an example it could

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be Ethernet to when the frame arrives at the rudder the rudder will strip the layer two headers and

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then send the frame across the when using for example HDL.

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So if this point to point connection is configured with a layer to encapsulation of each deal see the

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Ethernet headers are removed and the original IP packet that was sent by P.S. 1 is encapsulated in HDL

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C and is forwarded across the serial link to a to When rather to receives the HDL C frame it strips

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the HDL C headers and forwards the original IP packet sent by P.S. 1 onto the local area network using

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an Ethernet header so the packet is encapsulated in Ethernet and an Ethan at frame is sent from router

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2 to P.S. to using ethernet so we have Ethernet on the local area network on the left the when encapsulation

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used is used between right one and rudder two.

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In this example it's HDL C and then on land too and Ethernet encapsulation is used once again the two

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layers that we going to concentrate on in the oversized model for when technologies is the physical

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layer and the data link layer at the physical layer.

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The physical presentation changes from what you've seen in an Ethan and environment.

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So rather than using RJ 45 connectors and for instance catch six cabling X 21 or V 35 cables would be

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used.

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So the physical characteristics of the when interface are different to the physical characteristics

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of Ethernet at least two rather than using an Ethan encapsulation you would encounter encapsulation

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such as frame relay BP HDL C A.T.M. and NPL less.

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You may however to day also encounter Ethernet when connections which are becoming more and more popular.

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But for the CCMA when discussing it point to point when connection we are going to be concentrating

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on a BPP and HDL C encapsulation.

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So what kind of when devices would you typically see for point to point connections.

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Well you'll typically find rudders rather than switches connecting remote sites together.

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You'd also encounter a CSU DSP or channel service unit data service unit which allows you to connect

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to a list line connection using for example an X 21 or V 35 cable.

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This converts the signals to the required format for when transmission.