- In this video,
we'll take a look at configuring
a very basic IP SLA.
This particular example
will not use an IP SLA Responder,
so we'll be creating a very basic configuration
that's going to use the ICMP Echo function
to check for the reachability of a device
on our network.
Exploring all the configurations of IP SLA
would encompass it's very own video series,
because they are numerous,
but in this example, and the subsequent videos,
we're going to cover the Cisco blueprint requirements
of making sure you know how to configure IP SLA,
and that you know where you can find
those additional configuration options.
You can see from on screen
that we have a really basic topology here.
We have a couple of interconnected routers
and we have a server.
You can see that the server
is sitting at 10.0.0.6, in this example,
and we're going to create a very simple IP SLA
that will check on the connectivity status
of the server,
so that we can be alerted if the server becomes unreachable.
You can verify whether or not your particular device
supports a specific IP SLA configuration
with the command "Show IP SLA application",
and under here we're going to see a list
of all the available IP SLA operations.
Not all of these operations are supported
on every single device,
so that is something to be aware of.
We can see here that we have several supported options,
which are fairly numerous,
we see ICMP Echo, we see Jitter,
we see voiceover IP, just to name a few of those,
so lots and lots of options.
We're here on Router 1,
let's start under Global Configuration mode,
and let's start with the command, "IP SLA,"
and if we look at contextual help,
we can follow that with an entry number,
so each IP SLA probe that we configure
will have it's own individual entry number
to identify it.
In this case, let's just use number one,
and if we hit "Enter",
we're now under IP SLA configuration mode on this router.
If we take a look at our contextual help options,
you can see all of the available operations
that we're able to configure.
In our case,
since we're testing basic reachability to our server,
we want to use the keyword "ICMP-echo",
and we need to follow that
with the IP address or host name
for the destination that we want to monitor.
In our case, that's the server at 10.0.0.6.
If we look at contextual help again,
we'll see that we have two optional keywords here.
We can specify the source IP address,
so in other words,
if we want to mark these ICMP packets from a specific source
we can do that,
or we can specify a source interface, as well.
We won't bother with either of those options,
in this case, we'll just hit "Enter."
Now notice we're under IP SLA ICMP Echo configuration mode,
so here we're setting options
for our ICMP Echo function.
If we look at contextual help,
you can see that we, again, have quite a few options here.
I want to choose the frequency option,
in this particular example,
and I want to set the frequency for this IP SLA probe.
Help indicates that this will be set in seconds,
so maybe we want this to probe every three minutes,
in my case, we can do that by putting in 180,
for 180 seconds.
We can see some results in our output, later,
since this is a lab environment
and I want to set that really low.
I'm actually going to set that to ten seconds,
we wouldn't want to do that
in production, most likely,
but here in this lab, it's okay to do that,
so I'll set that to ten.
We can run any additional sub-commands here
that you want to.
If we wanted to set things like threshold,
or timeouts, we could run those
under this ICMP Echo configuration mode, as well.
In my case, I'm going to keep it pretty simple,
I'm gon leave it basic,
and I'm gon leave it right there.
Want to hit 'Enter'
and I'm going to go back to Global Configuration mode now.
Now that we have our IP SLA configured,
we need to actually start the probe.
If we say
IP SLA,
and we look at our contextual help again,
near the bottom we see this schedule keyword
that allows us to schedule the entry,
schedule a start time for that.
It's going to allow us to schedule parameters
for each of our IP SLA operations.
We can say "schedule,"
and we need to follow that
with the entry number that we're scheduling,
which is, of course, one,
and help indicates more options for this probe,
such as when it should start,
and how long it should operate.
So to start with, let's say "Start-time,"
and again under those options, we see a few things,
we can set this to start after a certain amount of time,
so say if we wanted to do that five minutes from now,
we could do that,
or we could set a very specific start time,
even down to the number of seconds.
We can make that pending,
so that it's activated,
but no information is collected, yet,
we could set it to random,
or we can set it to now.
In my case, I want to set that to "now,"
I want it to start right away,
and if we look at contextual help again,
we can see the "recurring" option,
so that's going to run this operation every day.
We can also age out the operation for memory
after a certain interval, if we want to do that,
or we can set a lifetime value.
I'm going to set a lifetime value,
so I'll say "life"
and if I look at contextual help,
you can see that by default,
that sets to 3600 seconds.
Since I want this to run indefinitely,
in this example, I'm going to say "forever,"
in our case, and I'm on hit "Enter"
and you can see right away what happens if we do that.
We get an error,
and that's because when we're in Recurring Mode
it's redundant to set a lifetime of more than one day,
so basically this is telling you
that these commands are redundant
and that one of those is unnecessary,
so I'm going to "arrow up"
and I'm going to remove that "recurring" keyword,
and I'm onna hit 'enter' to accept that.
If we back out of here,
and we say,
"Show IP SLA configuration one",
which is the one that we just configured,
you can see that our configuration
is displayed in this output.
We can see that this is, at the top, an ICMP Echo operation.
We see that pointing over to the 10.0.0.6 destination.
The source address is listed as all zeroes,
meaning that any valid IP address on this router
will be set as a source,
and we can see our next scheduled start time
is set to "already passed,"
so that's good, it's already up and going,
and just above that we can see our operation frequency
that we set, which is every ten seconds,
so that's good,
and that is also never going to age out.
We can see that it's listed as a "lifetime,"
life seconds are listed as "forever."
If we run the command "Show IP SLA statistics,"
then we can see some information about this.
We get a more basic output,
letting us know that we have
IP SLA operation number one running.
We see our last round-trip time,
we can see our number of successes,
we can see our return code,
our last return code was "OK,"
meaning that this hasn't crossed
any thresholds that we've set,
and we would -
additionally if we had any failures -
we would see failures in here.
We do see eight successes,
so we've had eight successes in this very short interval.
Let me jump over to Router Two,
let's go under our interface,
"gig zero/2," in this case,
and let's say "shut,"
we want to shut down that port,
so that now the interface,
where the server is connected, has been shut down,
and the server is going to be unreachable
by our IP SLA probe.
IP SLA would be sending out
SNMP trap messages about these failures,
and those would go out via Syslog.
Those would be handled by a Syslog server,
and an administrator would be alerted,
depending on how we've configured that.
But we can also see this on the local router
that we just looked at.
If we go back to Router One
and we, again, run that same "show" command,
if we say "show IP SLA statistics"
and at this time notice
that the last operation return code
was a timeout,
and we're up to three failures now,
so we see that is populating in our IP SLA statistics.
We see that there's not a lot of information here,
but we can see that it's a failure.
A really good Syslog server
is going to be much more helpful
when we're alerting about these types of violations.
We wouldn't want to depend on
the output of this "show" command.
We would want this to work together
with some sort of SNMP alerting system.
So that's a basic look at IP SLA configuration
using the ICMP Echo function
to monitor the reachability of a network device.