When it comes to a color, it's important for us to understand what exactly it
is.
It is a string.
In coding terms, a string is a series of letters and numbers that usually
represent text.
So as I look at the list of colors here on the screen, this is the all-in
clusive list
of colors that Cisco gives us as part of the SD-WAN solution.
It's important to note that I cannot create my own colors, even though it's a
string.
I couldn't go in there and create a color called Jeff or CBT or whatever I want
.
Instead, I have to use the colors that they've provided.
And at the time of this video, these, again, this is the all-inclusive list of
all of the
colors that are available.
And so when we look at them, we can tell what they're sort of intended to be
used for.
So we've got the two different internets up here for Republic and Biz, which
kind of
makes me laugh.
It's short for business.
We usually very much a slaying term for that, but we're comparing our internal
internet
to a public internet type of situation.
And then we've got LTE and 3G.
These are our four cellular connections.
Then we have some interesting ones because these are true colors.
Hey, what do you know?
We could actually assign a color as our color.
So red or blue or green, these would be a little bit more arbitrary, just
assigning random
colors to our circuits.
But then we also have less arbitrary ones.
We have this tiered bronze, silver and gold.
When we think about Olympic medals and the like, we can see that, or we used to
would
expect that the gold circuit would probably be our best circuit, especially
compared to
bronze and silver circuits.
And then we've got MPLS and Metro Ethernet up here.
And then we have just a bunch of very generic ones.
We have private one through six.
We have custom ones through three where we would assign the value ourselves.
And we just have to know when we pull up a T lock and we see color in there for
custom
two, we have to know what that means.
And then as we might imagine, there's a default color, which is what gets
assigned by default
when the system first comes online.
So why do I have them in two different columns like this?
Well, these colors are known as our public colors.
These are intended to be used on circuits that generally speaking are going to
have devices
on it using public IP addresses.
So if I connect an edge device to an internet circuit, I'm usually going to
have a public
IP address associated with this device.
Now it can be behind that and we'll talk about NAT here coming up.
It's a very important part of this conversation.
But generally speaking, we're expecting there to be a public IP address
available for me
to connect to my edge devices if I'm using public colors.
Meanwhile over on the right here, if there's a public side, then there's
probably going
to be a private side, which probably explains the private color here that we
could associate
with this.
So this, when we're talking about private colors, we are expecting there to be
the use
of private IP addresses.
But IP addresses being those RFC 1918 addresses such as 10.0.0.0 and 192.168
and so on and
so forth.
So why do we care from a technical perspective, what is the difference between
using public
and private colors?
Well, when we have two devices trying to communicate to one another and form a
tunnel, we're going
to have to decide which IP address.
So what is my destination IP address when I'm sending the packet to the other
side?
Am I going to use a public address or a private address?
Well, what's interesting about this is when we send those T-lock routes from
our V smart,
our controller, again, when that comes down, it's going to include both the
private IP address
as well as the public IP address for that specific T-lock.
And so if we're behind that, for example, we're going to have a private and a
public
IP address.
So the question is, which one of these am I going to use to connect to the
other side?
So if I have a public and a public from a color perspective, so I'm using a
public color
here, remember, we can connect between two different T-locks.
This could be a T-lock for LTE and this could be a T-lock for Metro Ethernet,
for example.
We're going to try to connect across T-locks as we talked about in the last
video.
So based on the T-lock, if this is a public T-lock connecting to a public T-
lock, then
as we might imagine, we're going to use a public IP address connecting to a
public IP
address.
But the reality is that even if one of these sites is using a private T-lock,
as long as
the other side is using a public, then we're still going to use public IP to
public IP.
The only time we're going to get these private IP addresses involved is if we
have a private
T-lock communicating with a private T-lock.
In this situation, we will use our private IP addresses to go from one tunnel
source
to the tunnel destination.
However, as long as one of the T-locks is indeed public, we will be using those
public
IP addresses.
So it's important to notice this as far as understanding which scenario will
result in
public versus private IP addresses being used.
So this is going to matter from a networking perspective.
This actually has implications when we're using it in our environments.
So we need to be very careful about deciding which color is going to be used
for a particular
circuit.
For example, I wouldn't want to arbitrarily use Metro Ethernet on an Internet
circuit
or something that has public IP addresses because that will change the
underlying packet
structure for our tunnel connections.
And it is worth noting, by the way, that when we're assigning colors, we can
only have one
color on one interface on a device per edge.
So I can't take an edge, have two different connections into the same Internet
service
provider and give them the same color.
So even if we have something like that, which is redundant connections, this is
going to
have to have two different colors.
So maybe in this case, I would use red and blue connecting to the same service
provider,
the same Internet circuit provider.
I could not do red and red because that would violate the one color to one
interface rule.
I'd have one color on two different interfaces at that point.
So maybe they're red and blue because they're roughly the same or maybe one
circuit's preferred
compared to the other and I'd use something like golden bronze.
Again, when we're talking about these strings, they're fairly arbitrary outside
of the public
and private designation.
I can use whatever color makes the most sense to me and my organization.
Now lastly, let's talk briefly, cut away from SD-WAN in general and talk
specifically
about this course and our lab environment.
We know that we have two different circuits represented by those layer two
switches.
One is supposed to represent the Internet, one is supposed to represent MPLS.
Now yes, our Internet is fake Internet.
It's just a network and it's actually using private IP addresses that 192.168.
255 range,
which may be used in your own environment and maybe you decided to deploy a
different range.
But either way, we understand that there's private IP addresses there and that
's perfectly
fine because we're not worrying about NAT.
We don't need to worry about there being a difference here in our T-lock routes
between
private and public IP addresses.
So what we're going to do when we take a device is we're going to look at these
devices.
We're going to see that Gig 1 connects into the Internet and Gig 2 connects to
our MPLS.
So we're going to use for our Gig 1 interface, the Biz Internet color.
We still have to configure this and we will coming up shortly.
And then Gig 2 is going to use, as we imagine, the MPLS color.
Now there is an exception with Edge 14.
It has a slightly different configuration and we'll take a look at that coming
up.
But just know that we're going to use Biz Internet and MPLS for the colors in
our lab
environment.
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