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So in our journey, we are right here testing DHCP services.

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Now, if we're going to set up an IP SLA to test and validate that DHCP is up

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and available,

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we probably ought to have a DHCP server somewhere in our topology, which at the

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moment, I don't.

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So let's take a moment and set up R2 as a DHCP server.

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And let's have it hand out IP addresses for the 10.0.12 address base.

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And its IP address on that subnet is .2.

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So we'll make that the default router as part of our DHCP services.

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Then once we set that up, we can set up R1 as a probe and do probes with an IP
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Then once we set that up, we can set up R1 as a probe and do probes with an IP

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SLA

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to validate that DHCP services are up and available and working.

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So with that in mind, let's head back to the topology and let's first configure

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DHCP services here on R2.

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So over to R2, we go, we'll click on the R2 tab and let's do a show, run, pipe,

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section DHCP.

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Just to verify we don't currently have anything set up, fantastic.

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So we'll go to configuration mode IP DHCP pool.

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Let's call this how about DHCP dash pool.
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Let's call this how about DHCP dash pool.

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Very creative, I know.

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And actually for the network, we'll do 10.

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What is that network?

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Let's take a peek together.

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That network is the 10.0.12 network.

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So we'll go ahead.

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So we'll go and set that network 10.0.12.0 with a slash 24 and it says

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ambiguous command.

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I need more than just net.

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Let's go ahead and type in net w that'll work.

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And now let's also set up a default gateway.

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So the default router be 10.0.12.2.

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That's our two's address and that'll be enough.
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That's our two's address and that'll be enough.

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Let's also do an IP DHCP exclude and let's exclude 10.0.12.1 all the way

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through 10.0.12 through 199.

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So the first IP address, it should be able to hand out is dot 200 on that sub

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net.

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Fantastic.

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And let's also do a debug of IP DHCP, a question mark server.

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And let's go ahead and do a debug on the actual packets.

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That'll be enough.

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That's a show debug and great DHCP server packet debugging is on.

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So any activity that happens with DHCP, we should be able to see some activity
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So any activity that happens with DHCP, we should be able to see some activity

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right here on our two.

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Next, let's head over to R1 and we'll configure the probe on R1 to test for

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DHCP services.

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And because we've used IPSLA IDs one, two, three and four for this one, we'll

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use IP SLA number five.

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So we'll go to the right router R1 and let's type in config T.

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So do show IP SLA summary.

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And sure enough, all of our SLAs are still running.

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That first one though is about the timeout, I think, because it's just running
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That first one though is about the timeout, I think, because it's just running

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for the default lifetime.

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So that may be not running soon, but it's running now and we'll do an IP SLA

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and we want to use five press enter.

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We'll do a question mark and what we want to do is the DHCP.

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So we'll go ahead and put in DHCP space and a question mark and then the IP

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address where the DHCP server is running,

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which is at 10.12, nope, 10.0.12.2.

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That's the IP address of our DHCP server space question mark.

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Now here we could also specify a source IP.
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Now here we could also specify a source IP.

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The benefit of setting up a source IP is that we could actually do tests based

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on where that request was coming from for a subnet in that range.

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But because I want to do the request from gig one zero on that same 10, 0, 12

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network,

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I'm just not going to add what source interface to use.

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We'll use the routing table and use that interface because it's the closest

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interface from a routing perspective

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to reach 10.0 at 12.

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So I'm going to go ahead and do DHCP 10.0.12.2 and press enter.

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Next, let's specify the frequency and for the frequency, let's use 30 seconds

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again.

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So we'll do a DHCP process of discover, offer request acknowledgement every 30
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So we'll do a DHCP process of discover, offer request acknowledgement every 30

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seconds.

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And that looks good.

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We'll do a do show run pipe section SLA and there's our current one.

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And if we do a do show IP SLA summary, so currently it's not running.

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So exit out of SLA configuration.

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And we'll type in IP SLA schedule five, start time now, life forever.

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Then if we do the same show command show IP SLA summary, now it is currently

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running.

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So initially there's a huge round trip time, but I expect that will go down.
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So initially there's a huge round trip time, but I expect that will go down.

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In fact, let's go ahead and take a peek over at R2.

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So we have some debug messages here.

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In fact, let me go ahead and turn that off.

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I'll do an alt turn off debugging.

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So if we scroll up, so we have a discover message that the server received and

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then it made an offer.

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And then there was a request from the client and there was a final

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acknowledgement.

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And then after that IP address was assigned, it handed out 10.0.12.200.

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The client, in this case it's R1, the probe, simply did a release.

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It says, you know what, I no longer need it.
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It says, you know what, I no longer need it.

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I want to release this IP address.

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And that process should happen over and over again every 30 seconds.

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So while we do that a minute or two to run, let's take a look at the packet

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captures on the network path between R1 and R2.

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So here's the packet capture. Let me go ahead and do a display filter for DHCP

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and press enter.

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And oh, there we go.

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And here's the process.

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We have our discover message here.

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That's coming from 10.0.12.1 going to our server at 10.0.12.2.

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Then we have the offer from the server back to the client.

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Then we have the request, the acknowledgement.
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Then we have the request, the acknowledgement.

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And then we have three releases.

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I guess it's being a little paranoid.

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So I want to make sure that it was releasing that IP address.

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It sent three based on the packets.

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It sent a release once, twice, three times.

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And then that process should have repeated again after another 60 seconds.

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So if we bring back the timestamps, call them, let me bring that back by

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showing time.

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So for the initial discover with this timestamp of 615 011, the next discover

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is at 64500, which is 30 seconds, 615 and that 645.
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is at 64500, which is 30 seconds, 615 and that 645.

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Oh, I thought I said it's 60 seconds.

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Maybe not.

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Let's go take a look.

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Going back to R1, we can do a show run.

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And I mean, configuration most will do a do, show run, pipe section SLA just to

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confirm.

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And sure enough, it's every 30 seconds.

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The packets are not lying.

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And now that it's run for a while, let's do a show IPSLA statistics for five

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for that SLA details press center and we've had eight successes.

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And we do a show IPSLA summary and press center.

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Wow, our round trip time for that service is really not great, especially
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Wow, our round trip time for that service is really not great, especially

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because it's on a local network, but that's OK.

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So if the DHCP server was not reachable, it would come back with a failure or

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if we set up a threshold for the round trip time.

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And we set the threshold, for example, to 1000 and this was 2000.

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That would also be a reason for this SLA to indicate there's a problem because

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it would be outside of the threshold that we set.

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So now that we've had some fun in configuring and verifying a few different

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types of IPSLA is the next video.

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I'd like to walk into one example of how we can use the results of an IPSLA to
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I'd like to walk into one example of how we can use the results of an IPSLA to

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control how the router is operating to trigger another action.

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So we get to do that in the next video and I'll see you there in just a moment.