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Alright friends, let's try and demystify these URLs. So like I said, the URL is

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directly tied

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to the Yang model and we know that we have different types of Yang models

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available, we have ITF,

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we have Cisco or other native models which include Cisco, Juniper, so on, so

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forth, as well as

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the Open Config models. So what I propose we do is we go to a website called

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GetUp, whereby all of

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these models are actually uploaded and we can download a copy of all of the

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available models and

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then we can begin inspecting them and from that point we can derive what our
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then we can begin inspecting them and from that point we can derive what our

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URL should actually be.

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So let me go and go to my browser here, so if you happen to search for Yang

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models GetUp,

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let's click this link here. Now what I'm going to do is I'm going to download a

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copy of everything

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that is in all of these folders, okay. So because I'm downloading from GetUp, I

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'm going to use

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a utility called GetSaults. They get clone and then paste in the address that I

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just saw there and

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if I enter we're going to begin downloading all of these files, okay. Now just

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whilst that

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downloads, if I go back to my browser, what we can actually see here is we have
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downloads, if I go back to my browser, what we can actually see here is we have

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a whole bunch of

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different folders, okay. So if I just go into say, for example, the standard

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folder, I can get down

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and go into IETF for the IETF models, if I go into RFC for the request for

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comments, what we actually

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see here are tons and tons and tons of these models. So we have IETF models for

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things like IPv4,

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Unicast routing, so if you've got some type of routing configuration, the

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information you would

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find would be in this model, whereas if you want to get, say for example, some

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interface information,

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if we scroll on up, what we can see here is the IETF interfaces yang model. Now
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if we scroll on up, what we can see here is the IETF interfaces yang model. Now

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one thing you'll

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notice is if we happen to just look at this right here and if you scroll

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through all of this,

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you are beginning to see that this looks kind of confusing, it's pretty complex

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and it really is

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very, very long. I can just keep scrolling and scrolling and scrolling. This is

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really, really hard

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to just look at this way and because of that, what I'm going to suggest we do

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is we use

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the utility that is going to transform this data into something that is at

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least a little bit more

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readable. So the utility that I'm going to use right now is something called pi
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readable. So the utility that I'm going to use right now is something called pi

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yang. It's basically

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a Python program that is going to, well, ingest these models. So I'll say pip3

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installed pi yang

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and to enter and then we begin installation. So now we're that done because I

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have downloaded the

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yang models, it's been downloaded into a directory called yang, which we can

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see right here. So if I

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just go into this folder and I do a listing, we actually see all of the same

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information that we

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saw on the website right there. We can go into the standard folder, we can go

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into vendor models,

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so on, so forth. So if I just go into the standard folder like we just saw
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so on, so forth. So if I just go into the standard folder like we just saw

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before and I do a listing

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and I go into the ITF folder and do a listing and again, our FC, we can see

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this is the exact same

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structure. So inside this folder, do a listing, we're going to see all of these

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models. So again,

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scrolling on up, we can see models for SNMP, segment routing, tons and tons and

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tons of stuff.

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But for now, let's go and grab the ITF interfaces model, okay? So if I just

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copy this right here,

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and grab you, what I will do is use my tool and say, pi yang dash f for the

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format, say I want to see

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this in a tree like format and then just paste in the model that we want to
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this in a tree like format and then just paste in the model that we want to

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inspect. If I hit enter,

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we now see this tree like structure. So let's go up to the very top, okay? So

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at the very top,

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we actually see the name of the module, okay? And then inside that, we have all

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of the model data,

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okay? So again, I know this is pretty confusing to look at. But honestly, we

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don't have to get too

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deep in the way to this, okay? So don't be discouraged. Try to follow along. So

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basically we have this top

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level container here called interfaces. And we can see it's actually out-dented

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here a little bit.

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And then everything within, this is all within that particular container, see
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And then everything within, this is all within that particular container, see

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that? Now I will say it

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gets more detailed than this. But for a good starting point, what we're going

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to do is to make a note

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of the module here, okay? And then we're going to make a note of the top level

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container. Okay,

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so just take those two pieces of information that we see right now, okay? And I

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'm going to basically

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combine them now, pause for a moment. These two values might actually be

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familiar. If you go back

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to our script, look at what we actually see here. This is the way we build our

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URL. We have the target
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URL. We have the target

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we're trying to reach and the port and then we say forward slash, rest corn

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forward slash data.

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That's a standard. After that, we now specify the information that we want to

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receive from the

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browser rather than the browser from the router. So the first portion here,

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this is me telling what

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yang model I want to be retrieving. Okay? And remember that's just what you saw

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right there. Okay?

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See it. This is the module name right here for all of this information. And

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then immediately after,

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what I have is a little colon separator, which we can see. And then right after
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what I have is a little colon separator, which we can see. And then right after

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we have that top

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level container. So think about it like this. If I wanted to get a different

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piece of information,

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how would I do that? But I would go through another yang model. I could then

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use pie yang. And from

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that point, I would quickly look at the module and then get the top level

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container. So here's the

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thing. If you go back into our yang folder here, and this time we go into the

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vendor folder. And now

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I go in and look for Cisco. And then I'm on a Cisco iOS XE device. So I'll go

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into this particular

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folder and all I have here are all of these revision numbers. So let's grab the
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folder and all I have here are all of these revision numbers. So let's grab the

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latest revision.

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So this one right here, going here. If I do a listing, we see all of these

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models. Okay?

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If I just grab the model that says native, this is essentially going to give me

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all of my running

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configuration. So let's just copy this here. And I'll say pie yang f dream. And

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I'll paste in the

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model once again, if I enter. So because this can model the entire

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configuration, this is an

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absolutely massive file. But if I go to the very top, what can we see here? I

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can see the name of

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the module, which is this right here. And then the top level container is this
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the module, which is this right here. And then the top level container is this

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one right here.

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Okay? So let's try to follow the same principles and return this data. So let

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me just

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copy this right here. Okay? And all I will do is I will copy it over the

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previous script. And I'll

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create one called script free dot py. So if I open this up, go in here and what

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I'm going to do here,

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if I just remove all of this. And I'll go and modify the actual path. Okay? So

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let's just take the URL,

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delete this, paste in the name of the module. Then we'll have a colon and then

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we'll use the top
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we'll use the top

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level container, which is native. Open in fact, before I do this, let me put my

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parentheses back in

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right here. And now I will say, Python 3 script 3 dot py and to enter. And now

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look at this, we get a

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whole bunch of different information we're seeing effectively. The running

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configuration, your show

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runs of the speak in this Yang model type data. So scrolling all the way up to

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the very top,

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we can actually see the information that we have here is the outer key and

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instead of that,

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we have our version, which returns the version number. If you want to scroll on

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down,

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we have a host name key, which tells me the name of the host. We also have a
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we have a host name key, which tells me the name of the host. We also have a

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router key. And instead

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of here, we can see that happens to be OSPF configured on this particular

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device. So there's two ways

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to actually approach this. We can just get this data very generally and get all

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this information back

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and then we can begin parsing it directly with Python. So say, for example,

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what I could do is

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copy the key right here. And then when I retrieve the data, I can paste in the

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key. So if I save this,

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clear the screen, read around the script, if I scroll all the way up to the

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very top once again.

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Now we can see we have removed that outer key. So I can now grab more
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Now we can see we have removed that outer key. So I can now grab more

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information. Let's try the

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version key right here. Okay. So again, paste your in. If I run it one more

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time, now we're just receiving

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back the version key. Here's what's happening here. I've got my Linux machine

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and I've got my

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REST CONF configured catalyst switch here. So right now, I'm sending an 80DP

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request to ultimately get

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back all of the native configuration. Okay. And this is actually sending back a

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ton of information

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back to my machine right here over the network. And at this point on my machine

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, I'm just effectively
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, I'm just effectively

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filtering all of that data locally right here to return this particular piece

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of information.

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As opposed to me sending a request just to target the native data and pull back

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tons and tons

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of that information being sent over the wire and filter it here. What I can

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actually do is I can just

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send a more specific URL to the actual server itself. And this will just send

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me over the very specific

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data that I want. So pretty much the filtering is happening over here, meaning

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that we're not having

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to send tons and tons of data over the network unnecessarily just to filter it
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to send tons and tons of data over the network unnecessarily just to filter it

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out locally.

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So as opposed to filtering it out with Python, let's actually filter it out

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directly from the server

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by specifying a more specific URL. So here's what I will do. I will delete the

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part of the time filtering

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just so I can see all the data one more time, run the script. And if I scroll

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on up to the very top,

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what if I just try to add the version directly within the URL itself? Okay. So

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check this out. What

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we'll do here is go back in this time. I will just say forward slash version

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and save you if I

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clear the screen and run the script. Look at this. The formatting might look a
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clear the screen and run the script. Look at this. The formatting might look a

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little bit different,

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but we're actually getting back the correct value in this time. We've only had

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the server send over

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a very tiny amount of data, just the specific details that we want. So

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similarly, why could do

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is go back again? Let's just remove this to get the more general information.

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Save you.

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Arrow up try again. Say for example, I wanted to get this banner information.

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Okay. Well, you'll

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notice that this banner is actually indented within this key. And this key is

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also indented within.

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This key. Okay. So this has been a beginning to get a little bit confusing. So
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This key. Okay. So this has been a beginning to get a little bit confusing. So

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we'll reference this key

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first. The most outer key. So if I just say forward slash banner, save you.

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Clear the screen,

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try again. Now we're getting the more banner specific information. So again,

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let's get the MOTD key.

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So I'll just say forward slash MOTD, save you. Run it again. Now we have the

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banner key right here.

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So if I just say forward slash banner one more time and run the script, here we

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can now see we're

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parsing at the actual banner within the device itself. And again, if I just log

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in and say SSH and

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just give the sandbox address. If I log in, indeed we can see here, this
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just give the sandbox address. If I log in, indeed we can see here, this

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actually is the banner that

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we're seeing. See that. So no doubt if this is the first time you're seeing

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this in action,

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risk on and Yang can be pretty confusing due to these URLs. But really as a

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recap, all we have to do

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is to download the models. We then choose the model that we want to use, say

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for example, an interface

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model. And then we can make a note of the module name and also specify the top

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level container.

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We then take this information, put it into a URL and then make a request to the
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We then take this information, put it into a URL and then make a request to the

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device. And this

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will return the information about that particular model. And from that point on

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, we can either work with

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the data programmatically via Python, which is going to include us sending,

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perhaps maybe a lot more

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information over the network. Or if we wish we can request that the server

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itself filters the

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information being sent back. But ultimately, walking through the data and just

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specifying more specific URLs.