So in our journey, we are right here testing DHCP services.
Now, if we're going to set up an IP SLA to test and validate that DHCP is up
and available,
we probably ought to have a DHCP server somewhere in our topology, which at the
moment, I don't.
So let's take a moment and set up R2 as a DHCP server.
And let's have it hand out IP addresses for the 10.0.12 address base.
And its IP address on that subnet is .2.
So we'll make that the default router as part of our DHCP services.
Then once we set that up, we can set up R1 as a probe and do probes with an IP WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Then once we set that up, we can set up R1 as a probe and do probes with an IP
SLA
to validate that DHCP services are up and available and working.
So with that in mind, let's head back to the topology and let's first configure
DHCP services here on R2.
So over to R2, we go, we'll click on the R2 tab and let's do a show, run, pipe,
section DHCP.
Just to verify we don't currently have anything set up, fantastic.
So we'll go to configuration mode IP DHCP pool.
Let's call this how about DHCP dash pool. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's call this how about DHCP dash pool.
Very creative, I know.
And actually for the network, we'll do 10.
What is that network?
Let's take a peek together.
That network is the 10.0.12 network.
So we'll go ahead.
So we'll go and set that network 10.0.12.0 with a slash 24 and it says
ambiguous command.
I need more than just net.
Let's go ahead and type in net w that'll work.
And now let's also set up a default gateway.
So the default router be 10.0.12.2.
That's our two's address and that'll be enough. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That's our two's address and that'll be enough.
Let's also do an IP DHCP exclude and let's exclude 10.0.12.1 all the way
through 10.0.12 through 199.
So the first IP address, it should be able to hand out is dot 200 on that sub
net.
Fantastic.
And let's also do a debug of IP DHCP, a question mark server.
And let's go ahead and do a debug on the actual packets.
That'll be enough.
That's a show debug and great DHCP server packet debugging is on.
So any activity that happens with DHCP, we should be able to see some activity WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So any activity that happens with DHCP, we should be able to see some activity
right here on our two.
Next, let's head over to R1 and we'll configure the probe on R1 to test for
DHCP services.
And because we've used IPSLA IDs one, two, three and four for this one, we'll
use IP SLA number five.
So we'll go to the right router R1 and let's type in config T.
So do show IP SLA summary.
And sure enough, all of our SLAs are still running.
That first one though is about the timeout, I think, because it's just running WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That first one though is about the timeout, I think, because it's just running
for the default lifetime.
So that may be not running soon, but it's running now and we'll do an IP SLA
and we want to use five press enter.
We'll do a question mark and what we want to do is the DHCP.
So we'll go ahead and put in DHCP space and a question mark and then the IP
address where the DHCP server is running,
which is at 10.12, nope, 10.0.12.2.
That's the IP address of our DHCP server space question mark.
Now here we could also specify a source IP. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now here we could also specify a source IP.
The benefit of setting up a source IP is that we could actually do tests based
on where that request was coming from for a subnet in that range.
But because I want to do the request from gig one zero on that same 10, 0, 12
network,
I'm just not going to add what source interface to use.
We'll use the routing table and use that interface because it's the closest
interface from a routing perspective
to reach 10.0 at 12.
So I'm going to go ahead and do DHCP 10.0.12.2 and press enter.
Next, let's specify the frequency and for the frequency, let's use 30 seconds
again.
So we'll do a DHCP process of discover, offer request acknowledgement every 30 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we'll do a DHCP process of discover, offer request acknowledgement every 30
seconds.
And that looks good.
We'll do a do show run pipe section SLA and there's our current one.
And if we do a do show IP SLA summary, so currently it's not running.
So exit out of SLA configuration.
And we'll type in IP SLA schedule five, start time now, life forever.
Then if we do the same show command show IP SLA summary, now it is currently
running.
So initially there's a huge round trip time, but I expect that will go down. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So initially there's a huge round trip time, but I expect that will go down.
In fact, let's go ahead and take a peek over at R2.
So we have some debug messages here.
In fact, let me go ahead and turn that off.
I'll do an alt turn off debugging.
So if we scroll up, so we have a discover message that the server received and
then it made an offer.
And then there was a request from the client and there was a final
acknowledgement.
And then after that IP address was assigned, it handed out 10.0.12.200.
The client, in this case it's R1, the probe, simply did a release.
It says, you know what, I no longer need it. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It says, you know what, I no longer need it.
I want to release this IP address.
And that process should happen over and over again every 30 seconds.
So while we do that a minute or two to run, let's take a look at the packet
captures on the network path between R1 and R2.
So here's the packet capture. Let me go ahead and do a display filter for DHCP
and press enter.
And oh, there we go.
And here's the process.
We have our discover message here.
That's coming from 10.0.12.1 going to our server at 10.0.12.2.
Then we have the offer from the server back to the client.
Then we have the request, the acknowledgement. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Then we have the request, the acknowledgement.
And then we have three releases.
I guess it's being a little paranoid.
So I want to make sure that it was releasing that IP address.
It sent three based on the packets.
It sent a release once, twice, three times.
And then that process should have repeated again after another 60 seconds.
So if we bring back the timestamps, call them, let me bring that back by
showing time.
So for the initial discover with this timestamp of 615 011, the next discover
is at 64500, which is 30 seconds, 615 and that 645. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
is at 64500, which is 30 seconds, 615 and that 645.
Oh, I thought I said it's 60 seconds.
Maybe not.
Let's go take a look.
Going back to R1, we can do a show run.
And I mean, configuration most will do a do, show run, pipe section SLA just to
confirm.
And sure enough, it's every 30 seconds.
The packets are not lying.
And now that it's run for a while, let's do a show IPSLA statistics for five
for that SLA details press center and we've had eight successes.
And we do a show IPSLA summary and press center.
Wow, our round trip time for that service is really not great, especially WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Wow, our round trip time for that service is really not great, especially
because it's on a local network, but that's OK.
So if the DHCP server was not reachable, it would come back with a failure or
if we set up a threshold for the round trip time.
And we set the threshold, for example, to 1000 and this was 2000.
That would also be a reason for this SLA to indicate there's a problem because
it would be outside of the threshold that we set.
So now that we've had some fun in configuring and verifying a few different
types of IPSLA is the next video.
I'd like to walk into one example of how we can use the results of an IPSLA to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'd like to walk into one example of how we can use the results of an IPSLA to
control how the router is operating to trigger another action.
So we get to do that in the next video and I'll see you there in just a moment.