There are two main types of encapsulation that we'll discuss in this course.
The first one is HDL C more high level data link control.
This is a layer to encapsulation once again that can be used across a leased line providing Layer 1
service or connectivity from one site to another.
Now you need to be aware that Cisco have extended the industry standard version of HDL C by adding an
extra field called the Type field HDL C is a very simple encapsulation and I'll demonstrate a y shock
capture of the frame in a moment.
But as an example we have a flag field address field control field and a frame check sequence field
Cisco have added a Type field to the frame.
So this is different to the ISO industry standard HDFC protocol Cisco devices do you use the Cisco HDL
C or C HDL C version by default and you'll notice it's very easy to set up a serial link using this
encapsulation essentially just have to put an IP address on your right interfaces and no shut to the
interfaces to get them to communicate with each other.
If you want to connect Cisco riders to non Cisco riders you're going to want to change the encapsulation
TPP which is an industry standard version of encapsulation.
Now the reason why Cisco added the proprietary field is to allow multiple highlight protocols to traverse
the link at the same time.
So in other words if you want to run IP version for an IP version 6 across a serial link simultaneously
the riders need a Type field to differentiate the frames that belong to IP version 4 vs. the frames
that belong to IP version 6 when the router receives an IP version 4 packet across a serial link.
So in this example Rider 2 receives an IP version for packet from rider 1.
Write it too needs to know that that packet should be processed by the IP version 4 protocol stack on
the rider when it receives a IP version 6 packet.
It needs to know that the packet is destined to the IP version 6 protocol stack and that's what the
Type field provides.
It essentially allows the riders to differentiate between multiple higher layer protocols and hence
Cisco extended the protocol to allow that functionality.
The Industry Standard Version of HDL C doesn't have that type field denoting high layer protocols.
It's very simple to configure.
HDL see between two broad as you would type as an example and write a 1 enable committee interface and
the relevant interface.
In this example Serial 1 slash 0.
You would configure the IP address on these several interface so IP address tendered 1 to 2 to one with
the mosque 2 4 5 2 4 5 2 4 5 2 5 2.
As an example which would be better than slash 24.
And then you specify encapsulation HDL C so it's as simple as that to configure HDL C all you type is
encapsulation HDL C and that is done by default for you.
So you don't actually need to configure that at all.