What we want to do next is take a look at those limits.
Remember, we've talked about two different limits that we can configure,
one of which is known as the send path limit,
and that's how many paths the controller is going to send down to other edges.
And the other one is the ECMP limit,
which tells an edge how many of those it's willing to deploy all at once.
So let's take a look at this from this perspective in our lab.
So we know we've got our controller up here.
It's off the top of the screen, so I'll just draw it like this.
It's hanging off of the Internet.
Edge 13 is going to advertise two paths to this 10.10.13 subnet.
Edge 14 is also going to advertise two paths,
so the controller sees a total of four paths.
Now, four happens to be the default value,
and so we don't have to worry about trying to decide which paths to send.
Instead, we're going to send all four of these paths down to each edge,
including edge 11.
Edge 11 also has the ECMP limit down here,
and this is a default value of four.
So keep in mind the difference between the limits.
The ECMP limit is on the edge,
and it's able to install all four of those paths by default into the routing table.
Meanwhile, the controller has the send path limit,
and that is what's going to define how many of those paths get sent down.
So we'll play around with this a little bit.
First of all, let's go ahead and just take a look at the OMP table,
just so we can do a before and after.
And then from there, what I want to do is reduce this to two and see what the effect is.
So maybe I'll draw that in a different color here.
So we want to reduce that to two,
and then we want to reduce this to two and see what the net effect is.
So let's go ahead and have some fun in the lab.
I'm on edge 11.
I'm just going to do a show SD-WAN OMP routes.
This is a really good command.
We're going to run this command a lot in an SD-WAN environment,
and we're trying to figure out what's going on.
So we just took a look at this in a great amount of detail.
I'm not going to spend too much time on it here,
but we know in VPN 10 we have this 10.10.13 subnet that we've been focused on.
We have four different paths, all learned from the vSmart,
and all four paths are being installed.
And we see that when we really expand this,
we see that two of these paths are being learned from edge 14.
Two of them are being learned from edge 13.
Okay.
So now what we want to do is we want to change the ECMP limit on edge 11.
So we can do that via CLI,
but keep in mind that in our lab environment, edges 11 and 12,
these are actually managed by the SD-WAN controller.
Or manager, rather.
And so I'm going to have to perform that configuration via manager,
but let's quickly take a look at what it would look like to perform that
configuration via CLI on edge 11.
So if I were to get onto edge 11, I can do a config test D,
and then I'm going to get onto my SD-WAN configuration and enter into OMP.
So these are OMP commands.
When I do a question mark here,
I can see quite a bit of what I'm allowed to do here.
For example, I can perform graceful restart commands.
We'll be talking about that coming up.
Best path selection commands.
But notice I've got two limits here.
I've got my ECMP limit and my send path limit.
Yeah, I can actually configure this on my edges.
So my edges could use a reduced limit in order to send fewer paths to the
controller to start with.
It's not just a controller config, but either way,
I just want to change the ECMP limit.
So I'd say ECMP limit here, question mark.
We see that I can add a limit up to 16,
and four is the current configuration.
This represents the current configuration,
which because we haven't configured it, is also the default.
So if I were to say two and then commit,
we're going to get this error message that says, hey, we're being,
is v-managed.
I like that.
It's being managed by v-manage,
and so I'm not allowed to perform this configuration.
Instead, I'm going to have to abort the config,
and we'll have to do that from our v-manage device.
So let's go ahead and go do that.
And like with most of our configuration,
we're going to come down to our templates.
And keep in mind what I said before,
when we are trying to know where in the UI I should be going to configure
things, think back to the CLI.
We just saw that we entered into OMP configuration mode,
and that's a pretty good tip for what we should expect for how we're going
to configure it on manager.
So I'm going to click add a template, look for my 8000V,
and notice that I do have a feature template for OMP.
If I click this, I'm going to get quite a few of those.
So we will call this OMP, and we're going to call it limit two.
And it adds ECMP limit two.
All right.
So we've got a name and description in place,
and now when I scroll down, again, we see graceful restart.
We see some other parameters like graceful restart timer,
and we also see these two limits.
Now, be careful.
This doesn't say that it's a limit.
It doesn't call it the send path limit here.
It just says the number of paths advertised per prefix.
So this is, though, that send path limit,
and we see it's a default value of four.
ECMP limit, default value of four as well.
So I'm going to go ahead and just globally change this to two.
That will change it on edges 11 and 12,
because that's what the device template is targeting.
And I'm just going to, let's see here,
make sure that all of these other configurations are fine.
Yep, we're good to go here.
See that we're advertising connected and static by default.
So everything, all the defaults should be good.
I'm going to save this and then go over to my device template,
and we're going to edit it.
And then we're going to scroll down until we see Cisco OMP right here,
and I'm going to select my OMP limit two.
And I'll click update,
and this will push the configuration out to these two devices.
So once this gets pushed out,
I can say configure devices and confirm.
Once this gets pushed out,
we're going to take a look at the CLI again to find out what exactly happens
when we add in a limit of two.
For now,
I'm going to pause the video until the configuration is confirmed.
All right, that's a mission success.
So let's go ahead and flip back over to our CLI.
And we see that some configuration has been done programmatically here by our manager.
So now let's go ahead and run those same commands.
So show SDWAN OMP routes.
And what we're expecting here is still to see four different paths.
So here's 10.10.13.0.
And now we see we have four different paths.
That's good.
And then extend it down.
Notice what happened.
Two of these paths are no longer getting installed into the routing table.
In fact, we're only installing the paths through edge 13, it appears.
So that's kind of interesting.
We've chosen edge 13.
we would figure out why that's the case.
It's probably just going to come down to the IP address or something along those lines.
But without diving into those details,
we just see that we've got two of them that are installed and two of them that are not.
Now notice that we configured the ECMP limit,
which is sort of on the inbound side.
So what that means is now that this is configured for a limit of two, that's great.
We're only installing two into our routing table.
But we are still receiving all four from the controller.
So let's say we wanted to clean this up a little bit.
What if we wanted the controller to not be sending all four of those?
Let's just send two because we're only going to install two.
Well, first of all, it might be good to have the two there in case the other two go down.
But let's just say we do want to clean it up.
So let's go and flip over to our controller.
Log back in here.
And so now that we're logged in, we can configure that send path limit.
So we're going to do a config T.
Now, interestingly, I don't do config dash T.
I do a config space T because this is a Viptela device and we don't need to differentiate between the two.
So we do a config T like normal.
And then I'm going to use my OMP command.
And I run question mark and we see a lot of the same commands.
Specifically, we see a few limits here.
We see send path limit.
And we see controller send path limit.
And we might say, well, where's the ECMP limit?
It doesn't go on the controller.
But what is the difference between send path limit, which is what we've been talking about,
the maximum number of paths sent for a prefix, and this controller send path limit?
Well, notice the description.
It's the number of paths we send to other vSmart controllers.
So I could limit the number of paths that I'm sending to other controllers.
But if I want to worry about what I'm sending to edges, it would be just the send path limit here.
So I'm going to type that in.
Send path limit.
And if I do a question mark, we again see our options with the current configuration of four.
I'm going to say send path limit two.
And we will do a commit and quit.
And we just updated the number of paths that we're sending down to our edges.
So let's go and go back to our edge.
Edge 11 one more time here.
Show SD-WAN OMP routes.
And we see for our site 13 subnet, 10.10.13.0, that now we actually are truly only getting two paths,
and we're installing both of them.
And the reason for that is because we're only sending two according to the send path limit,
and we're only installing two based on the ECMP limit.
In fact, I could get rid of the ECMP limit now.
I'd still only install two because I only am receiving two.
So it's very important for us to follow along with what really happened here.
We need to understand the difference between routes getting advertised into the controller
versus the controller advertising down to the edges.
We need to install or understand the difference between the two limits.
And we need to understand how OMP routes are showing up in the OMP table
and then how those get installed into the routing table.
So hopefully this is creating a pretty good picture of how all of this comes together
so that we can perform configuration as needed into our production environments.
Now, before we go, we'll want to make sure that we revert these changes
so it doesn't cause us problems later.
So I will go ahead and go to the controller, do a config T, OMP, send path limit of four, commit and quit.
And then I'll get on to the manager interface real quick.
And we'll go back to our, let's just go back to configuration and templates
and get on to the device template here and then scroll down to our OMP section.
and we'll push that configuration to the controllers.
So once this is pushed out, we just have to make sure that we are indeed still receiving four paths
and that we're installing all four paths into the routing table.