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So in our journey we've done all these IPSLAs, fantastic.

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And this today I'd like to walk you through one example out of many that we

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could use for tracking

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and using the results of an IPSLA. So for this demonstration let's imagine

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that we have R3 or we want to set up a default route on R3 that points to this

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interface here on

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R4 which is 10.0.34. Let me use a different color here, one that'll show up

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better. The default route

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would go to the next top of 10.0.34.4 which is this interface address right
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would go to the next top of 10.0.34.4 which is this interface address right

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here. However,

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if this router is not available we may not want to have that default route in

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place. In fact I'm

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sure of it because the traffic we'd be saying there would be unroutable beyond

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that point if

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R4 is not available. So what we could do is we could set up an IPSLA to go

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ahead and verify reachability

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to let's go ahead and use the loopback of R4.4.4.4.4. And for our game plan let

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's use IPSLA 33 here on R3.

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Now for an IPSLA we could care about just reachability, use for example an ICP
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Now for an IPSLA we could care about just reachability, use for example an ICP

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echo for IPSLA or we could

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use a jitter or some other option with a threshold. So whether we're outside of

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our threshold or the

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connectivity altogether has failed either one of those would cause that SLA to

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indicate that

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there's a problem. Now if we want to take action based on that what we could

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also do is we could

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set up tracking. So we could say you know what Mr. R3 I want to track this SLA

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33 so let's use track

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she's track ID number one. So you could use track ID 33 but then it gets a
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she's track ID number one. So you could use track ID 33 but then it gets a

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little bit confusing about

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do they have to match or not they don't. So we could set up tracking for

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example track ID number

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one that's paying attention to the IPSLA 33 whether it's okay or not. And then

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we could leverage that

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tracking in combination with our configuration on the router. So if we set up a

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default route

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and we said hey dear Mr. R3 that's your default route if tracking number one is

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okay. And if tracking

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number one is okay it's because the IPSLA 33 is functioning and is okay as well

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. So if we follow

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the bouncing ball the static route here is dependent on tracking ID one and
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the bouncing ball the static route here is dependent on tracking ID one and

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tracking ID one is paying

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attention to IPSLA 33. So let's just give you a taste of some of the options

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available if we have

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IPSLA's in place and then we want to track those SLAs. So with that in mind let

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's go to R3 and let's

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configure an IPSLA 33 that's set up to use 4444 to verify reachability and then

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we'll set up a

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static route a static default route with this next hop but we'll make

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conditional upon track number

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one saying everything's okay. So let's head over to R3 and here is our three
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one saying everything's okay. So let's head over to R3 and here is our three

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let's just check

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it's routing table real quick with a show IP route and it has no default route

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so there'll be a good

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demo here. Let's also do a ping to 4.4.4.4 just to make sure it's reachable and

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it is that's the

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loopback interface on R4 just to verify that let's go to R4 and we'll do a show

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IP interface brief

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and sure enough there's the loopback interface 4444 that R4 is responsible for.

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Let's go back to R3

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and let's turn on debugging. We'll do a debug IP routing. Now this is a tip I
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and let's turn on debugging. We'll do a debug IP routing. Now this is a tip I

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learned more than

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two decades ago when I got my first CCIE and that is if you have debug IP

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routing enabled

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then if your routing tables are changing you're going to get console messages

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indicating that's

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happening. So if we're adding a feature or a function and all of a sudden our

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routing tables

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start changing or flapping we've caused our own problem. So when setting up new

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controls in place

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on our routers it's a really great feature just to turn on temporarily so you

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can see whether or not

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what we're configuring like an access control list or something else is having
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what we're configuring like an access control list or something else is having

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a negative impact

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or negative the impacting it should say our routing. So debug IP routing is on

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and let's go

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ahead and let's first of all set up our IP SLA. So in configuration mode we'll

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type in IP SLA

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and based on our plan we want to use ID33 and as far as what we want to track

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let's just go ahead

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and track on a basic ping request. So we don't have to tell our fore it's an IP

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SLA responder because

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if we send a ping request it's going to respond. So we needed additional

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features or functions
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features or functions

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and some of the other SLAs we might want to do IP SLA responder on our fore but

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in this case we

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don't need to. So here we'll go ahead and put an ICMP-echo space question mark

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and the target we want to

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target is 4444 space question mark and for the source IP we can specify what if

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we want to only

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leave it alone and press enter and then now as part of this IP SLA that's doing

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an echo request

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just to verify basic connectivity let's specify the frequency to every about
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just to verify basic connectivity let's specify the frequency to every about

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every 10 seconds

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and we really don't need to specify a threshold in milliseconds because if we

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don't get a response

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to our echo request the IP SLA is going to fail I mean it's going to indicate

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that there's a problem.

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So now let's go ahead and do a do show IP SLA summary we should only have one

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here that's 33

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it's not currently running so we'll do an IP SLA schedule the ID number for our

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SLA which is 33

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and we'll go ahead and say start time and we'll specify now and let's go ahead

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and say the lifetime

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is going to be forever so it's just going to run indefinitely then we'll do a
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is going to be forever so it's just going to run indefinitely then we'll do a

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do show IP SLA summary

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and it is running the round trip time is 52 the return code is okay and because

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it's happening

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every 10 seconds if we do a do show IP statistics for SLA 33 and then the

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keyword details press

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enter I forgot the keyword SLA so I thought it but I didn't say it so do a show

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IP SLA space

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statistics 33 details we've had five successes our latest round trip time is 20

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milliseconds and

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the latest operation return code is okay so now let's go ahead and leverage
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the latest operation return code is okay so now let's go ahead and leverage

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that with something

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known as tracking so to subtracting in configuration mode we simply use the

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command track space

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question mark and then we're going to put an attract object number so here you

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can just use

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some unique number on this local router so let's use track ID number one space

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question mark and

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let's specify we want to track on an IPS LA so we'll have an IP space SLA space

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question mark and

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then we want to track on IPS LA 33 space and the question mark so regarding the
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then we want to track on IPS LA 33 space and the question mark so regarding the

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SLA if we use the

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keyword reachability it just means that that target is no longer reachable or

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if we said state

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and we had a threshold for example of a hundred for the round trip time and it

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was over that

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threshold that would also cause track one to fail so in our case because we're

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only doing an

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ICMP echo request effectively a ping request let's go ahead and we can go ahead

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and simply put in

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reachability and enter and then we can put in parameters here as well so I'm

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going to go ahead

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and and out of that and we'll do a show IP SLA summary which is show us our IP
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and and out of that and we'll do a show IP SLA summary which is show us our IP

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SLA which is

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currently okay and show track and that will show us our tracking so this

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tracking track number one

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is tracking on IPS LA 33 reachability and reachability is currently up so now

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if we use this tracking as

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part of a route for example let's do that right now let's do a config T an IP

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route uh default route

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and let's take a look at our topology for a moment so if we want the default

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route that's going to use

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our for the 10 0 34 dot four address as is next top for the default route we
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our for the 10 0 34 dot four address as is next top for the default route we

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want to make that

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conditional upon track one being up we can simply tack on that tracker as part

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of our static route

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and so if the tracker shows as down it'll remove the route from the routing

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table if the tracking

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shows us up it'll put the route back into the routing table so we'll put the

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next top address

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of 10 dot 0 dot 34 dot 4 space and a question mark and check it out here we can

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use the keyword

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track so we'll type in track space and then our tracked object number which is

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object number

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one right there for tracking so go ahead and put one so track number one is
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one right there for tracking so go ahead and put one so track number one is

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looking at IPS LA

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33 for reachability and assuming everything's good it'll add this route to the

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routing table

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so press enter and because debug IP routing is on it's now showing us that it

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just added that

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static route static default route to be specific with the next top of 10 dot 0

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34 dot 4 it added

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that to the routing table so if we do a show IP route there's that static route

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right there

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the reason that's working is because we have an IPS LA 33 that's running and if

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we do a show

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track that tracker based on what IPS LA 33 is indicating is saying yep we're
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track that tracker based on what IPS LA 33 is indicating is saying yep we're

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good to go we're

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okay so let's go ahead and remove 4 4 4 from the equation so if we go to our 4

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and we go ahead

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and interface configuration mode for loopback 0 when we say shutdown we're now

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no longer having

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reachability that 4 4 4 4 because it's shut down so we go back to our three

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here's the debug

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for the tracker tracker ID one which is matching on sla 33 it went from up to

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down then we have

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the static route being removed from the routing table and we also this is an O
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the static route being removed from the routing table and we also this is an O

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SPF one right here

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we also have the route to 4 4 4 4 explicitly being deleted from the routing

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table based on OSPF

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so now if we do a show IP route press enter we no longer have that default

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route however if we go

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back to our 4 and we say no shutdown that loopback 0 interface so now 4 4 4 4

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is reachable we should

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get that route back via OSPF and based on the console messages about to come up

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here we should

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also have our default route back so there's our OSPF learned route that we just

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put back in the

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routing table and there's the going from down to up and now we have our new
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routing table and there's the going from down to up and now we have our new

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static route that's

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also now back in the routing table so we do a show IP route once again and

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press center there's

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our static route once again so now that we have walked through the

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configuration of several different

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types of IP SLAs and also given a quick example of how to do tracking on one of

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those SLAs in the

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next video I'd like to put you on a hands-on lab with some specific tasks you

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can practice your

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configuration and verification of IP SLAs on a Cisco router so I will see you

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my friend in the next
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my friend in the next

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video in just a moment