If you don't have access to a point to point a serial connection at work just do a search in Google
or your favorite search engine for Cisco CSU D issue as an example and you'll find many pictures showing
you examples of setups using serial connections.
Here's a very good one.
It's an older picture showing a 17 20 Rada in the picture.
Here you can see the blue console cable connecting to the console port of the rudder.
You can see the power connection and what's important is to note the Ethernet connection.
This would connect to the up to a switch or another device in the local area network and very importantly
notice the V 35 cable.
So we have one end of the cable connected to the router and the other end is connected to the C issue
D issue.
This is an example of an external C issue issue and you can see it's connected to the telco network.
Now they use the term D Mark a D Mark is a demarcation point.
This is where responsibility changes.
So on one side of the D Mark or demarcation point any problems are the responsibility of the service
provider.
On the other side of the demarcation point any problems are yours.
If you managing the local area network so you would be responsible as an example for configuring your
router for making sure that the serial cable is connected correctly that the ethernet cable is connected
correctly that these devices are powered up and so forth but once you send traffic to the service provider
network that becomes the responsibility of the service provider.
Now these days they see issue.
The issue is often built in to the way an interface card or work.
This is an example of a week or one interface card that you would insert in a router.
Notice this one is a T1 issue C issue so the C issue D issues internal to the rudder.
Here's another picture of the week card and here's another one showing it inserted into the rudder.
So once again here's an example of the C issue D issue bolting to the rudder here's another example
showing you the C issue.
The issue with a DTV cable connected to the router providing an internet connection.
Cisco also have images such as the following showing that a serial connection is connected to a card
on the router which in turn connects you to the sea issue.
DC.