So in our journey we've done all these IPSLAs, fantastic.
And this today I'd like to walk you through one example out of many that we
could use for tracking
and using the results of an IPSLA. So for this demonstration let's imagine
that we have R3 or we want to set up a default route on R3 that points to this
interface here on
R4 which is 10.0.34. Let me use a different color here, one that'll show up
better. The default route
would go to the next top of 10.0.34.4 which is this interface address right WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
would go to the next top of 10.0.34.4 which is this interface address right
here. However,
if this router is not available we may not want to have that default route in
place. In fact I'm
sure of it because the traffic we'd be saying there would be unroutable beyond
that point if
R4 is not available. So what we could do is we could set up an IPSLA to go
ahead and verify reachability
to let's go ahead and use the loopback of R4.4.4.4.4. And for our game plan let
's use IPSLA 33 here on R3.
Now for an IPSLA we could care about just reachability, use for example an ICP WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now for an IPSLA we could care about just reachability, use for example an ICP
echo for IPSLA or we could
use a jitter or some other option with a threshold. So whether we're outside of
our threshold or the
connectivity altogether has failed either one of those would cause that SLA to
indicate that
there's a problem. Now if we want to take action based on that what we could
also do is we could
set up tracking. So we could say you know what Mr. R3 I want to track this SLA
33 so let's use track
she's track ID number one. So you could use track ID 33 but then it gets a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
she's track ID number one. So you could use track ID 33 but then it gets a
little bit confusing about
do they have to match or not they don't. So we could set up tracking for
example track ID number
one that's paying attention to the IPSLA 33 whether it's okay or not. And then
we could leverage that
tracking in combination with our configuration on the router. So if we set up a
default route
and we said hey dear Mr. R3 that's your default route if tracking number one is
okay. And if tracking
number one is okay it's because the IPSLA 33 is functioning and is okay as well
. So if we follow
the bouncing ball the static route here is dependent on tracking ID one and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
the bouncing ball the static route here is dependent on tracking ID one and
tracking ID one is paying
attention to IPSLA 33. So let's just give you a taste of some of the options
available if we have
IPSLA's in place and then we want to track those SLAs. So with that in mind let
's go to R3 and let's
configure an IPSLA 33 that's set up to use 4444 to verify reachability and then
we'll set up a
static route a static default route with this next hop but we'll make
conditional upon track number
one saying everything's okay. So let's head over to R3 and here is our three WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
one saying everything's okay. So let's head over to R3 and here is our three
let's just check
it's routing table real quick with a show IP route and it has no default route
so there'll be a good
demo here. Let's also do a ping to 4.4.4.4 just to make sure it's reachable and
it is that's the
loopback interface on R4 just to verify that let's go to R4 and we'll do a show
IP interface brief
and sure enough there's the loopback interface 4444 that R4 is responsible for.
Let's go back to R3
and let's turn on debugging. We'll do a debug IP routing. Now this is a tip I WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and let's turn on debugging. We'll do a debug IP routing. Now this is a tip I
learned more than
two decades ago when I got my first CCIE and that is if you have debug IP
routing enabled
then if your routing tables are changing you're going to get console messages
indicating that's
happening. So if we're adding a feature or a function and all of a sudden our
routing tables
start changing or flapping we've caused our own problem. So when setting up new
controls in place
on our routers it's a really great feature just to turn on temporarily so you
can see whether or not
what we're configuring like an access control list or something else is having WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
what we're configuring like an access control list or something else is having
a negative impact
or negative the impacting it should say our routing. So debug IP routing is on
and let's go
ahead and let's first of all set up our IP SLA. So in configuration mode we'll
type in IP SLA
and based on our plan we want to use ID33 and as far as what we want to track
let's just go ahead
and track on a basic ping request. So we don't have to tell our fore it's an IP
SLA responder because
if we send a ping request it's going to respond. So we needed additional
features or functions WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
features or functions
and some of the other SLAs we might want to do IP SLA responder on our fore but
in this case we
don't need to. So here we'll go ahead and put an ICMP-echo space question mark
and the target we want to
target is 4444 space question mark and for the source IP we can specify what if
we want to only
leave it alone and press enter and then now as part of this IP SLA that's doing
an echo request
just to verify basic connectivity let's specify the frequency to every about WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
just to verify basic connectivity let's specify the frequency to every about
every 10 seconds
and we really don't need to specify a threshold in milliseconds because if we
don't get a response
to our echo request the IP SLA is going to fail I mean it's going to indicate
that there's a problem.
So now let's go ahead and do a do show IP SLA summary we should only have one
here that's 33
it's not currently running so we'll do an IP SLA schedule the ID number for our
SLA which is 33
and we'll go ahead and say start time and we'll specify now and let's go ahead
and say the lifetime
is going to be forever so it's just going to run indefinitely then we'll do a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
is going to be forever so it's just going to run indefinitely then we'll do a
do show IP SLA summary
and it is running the round trip time is 52 the return code is okay and because
it's happening
every 10 seconds if we do a do show IP statistics for SLA 33 and then the
keyword details press
enter I forgot the keyword SLA so I thought it but I didn't say it so do a show
IP SLA space
statistics 33 details we've had five successes our latest round trip time is 20
milliseconds and
the latest operation return code is okay so now let's go ahead and leverage WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
the latest operation return code is okay so now let's go ahead and leverage
that with something
known as tracking so to subtracting in configuration mode we simply use the
command track space
question mark and then we're going to put an attract object number so here you
can just use
some unique number on this local router so let's use track ID number one space
question mark and
let's specify we want to track on an IPS LA so we'll have an IP space SLA space
question mark and
then we want to track on IPS LA 33 space and the question mark so regarding the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
then we want to track on IPS LA 33 space and the question mark so regarding the
SLA if we use the
keyword reachability it just means that that target is no longer reachable or
if we said state
and we had a threshold for example of a hundred for the round trip time and it
was over that
threshold that would also cause track one to fail so in our case because we're
only doing an
ICMP echo request effectively a ping request let's go ahead and we can go ahead
and simply put in
reachability and enter and then we can put in parameters here as well so I'm
going to go ahead
and and out of that and we'll do a show IP SLA summary which is show us our IP WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and and out of that and we'll do a show IP SLA summary which is show us our IP
SLA which is
currently okay and show track and that will show us our tracking so this
tracking track number one
is tracking on IPS LA 33 reachability and reachability is currently up so now
if we use this tracking as
part of a route for example let's do that right now let's do a config T an IP
route uh default route
and let's take a look at our topology for a moment so if we want the default
route that's going to use
our for the 10 0 34 dot four address as is next top for the default route we WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
our for the 10 0 34 dot four address as is next top for the default route we
want to make that
conditional upon track one being up we can simply tack on that tracker as part
of our static route
and so if the tracker shows as down it'll remove the route from the routing
table if the tracking
shows us up it'll put the route back into the routing table so we'll put the
next top address
of 10 dot 0 dot 34 dot 4 space and a question mark and check it out here we can
use the keyword
track so we'll type in track space and then our tracked object number which is
object number
one right there for tracking so go ahead and put one so track number one is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
one right there for tracking so go ahead and put one so track number one is
looking at IPS LA
33 for reachability and assuming everything's good it'll add this route to the
routing table
so press enter and because debug IP routing is on it's now showing us that it
just added that
static route static default route to be specific with the next top of 10 dot 0
34 dot 4 it added
that to the routing table so if we do a show IP route there's that static route
right there
the reason that's working is because we have an IPS LA 33 that's running and if
we do a show
track that tracker based on what IPS LA 33 is indicating is saying yep we're WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
track that tracker based on what IPS LA 33 is indicating is saying yep we're
good to go we're
okay so let's go ahead and remove 4 4 4 from the equation so if we go to our 4
and we go ahead
and interface configuration mode for loopback 0 when we say shutdown we're now
no longer having
reachability that 4 4 4 4 because it's shut down so we go back to our three
here's the debug
for the tracker tracker ID one which is matching on sla 33 it went from up to
down then we have
the static route being removed from the routing table and we also this is an O WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
the static route being removed from the routing table and we also this is an O
SPF one right here
we also have the route to 4 4 4 4 explicitly being deleted from the routing
table based on OSPF
so now if we do a show IP route press enter we no longer have that default
route however if we go
back to our 4 and we say no shutdown that loopback 0 interface so now 4 4 4 4
is reachable we should
get that route back via OSPF and based on the console messages about to come up
here we should
also have our default route back so there's our OSPF learned route that we just
put back in the
routing table and there's the going from down to up and now we have our new WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
routing table and there's the going from down to up and now we have our new
static route that's
also now back in the routing table so we do a show IP route once again and
press center there's
our static route once again so now that we have walked through the
configuration of several different
types of IP SLAs and also given a quick example of how to do tracking on one of
those SLAs in the
next video I'd like to put you on a hands-on lab with some specific tasks you
can practice your
configuration and verification of IP SLAs on a Cisco router so I will see you
my friend in the next WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
my friend in the next
video in just a moment