So here are the lab tasks and without further ado,
let's head over to the lab environment and let's do
the walkthrough of these lab tasks together.
So I have just reset the lab environment using
the reset option over here on the right and in a few moments,
it'll be rocking and ready to go.
All right, and here we go.
I just wanted to get a quick peek at the topology,
which is sitting right here on the desktop.
Great, great, great. So our first task is set up R1 and R2 as
a Stratum 1 NTP server.
Effectively, they're going to trust their own time.
So let's do that first. Let's open up server 1 by double-clicking WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's do that first. Let's open up server 1 by double-clicking
here on server 1 NUG.
Give that a moment to open up and that'll give us console access
to all of our network devices.
All right, so there we go. So here on R1,
let's go and do a quick show NTP status to make sure we're
starting off with nothing configured for NTP.
Then we're going to configuration mode and type in NTP master
and stratum 1 and boom, we're good to go.
Now, debug is already enabled on this.
I left it running from before.
So when you start this lab, if you don't want debug,
just do an undibug all right here from privilege mode and turn it off. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
just do an undibug all right here from privilege mode and turn it off.
So we do a show NTP status.
It basically says, yeah, I'm synchronized to myself.
I'm stratum 1, reference is local,
and we do a show NTP associations, a press center.
So we're synchronized with a loop back address.
We have reachability.
We're syncing with ourselves and we're good to go.
So we'll do the same thing over on R2.
So we'll do R2 and VigT.
Let's do a do, show NTP status.
Just to verify that it's not yet configured and type in NTP master. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Just to verify that it's not yet configured and type in NTP master.
And even though the lab didn't say so, I'm going to go ahead and say this too.
Just to give you a reinforcement that if this is a master level 2,
then clients that synchronize with the server would be considered 3.
So just add one for each hop in the path as you go down the line
for devices getting their time from NTP servers.
So now if we did a show NTP status and press center,
we are a stratum 2 and we do a show NTP associations.
It's going to confirm for us as well that we are ready to go.
All right, so next, let's go ahead and set up R3 as a client to R1 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
All right, so next, let's go ahead and set up R3 as a client to R1
and R4 as a client to R2.
So good to R3 first, NTP server, a 1.1.1.1 source interface,
loop back zero, and we'll go ahead and say burst.
And we'll do a similar treatment to R4, except on R4,
we'll do a config T and NTP server.
Point of loop back on R2.
We use our source address of 4444, which is loop back interface,
zeros address, let's also use the keyword burst, and we are good to go. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
zeros address, let's also use the keyword burst, and we are good to go.
Then we'll verify our configuration.
So back on R3, we'll do a show NTP status, press center, and it is synchronized
.
Now in your lab environment, that may take a minute or two to happen.
So while that does, you can do a debug and watch the back and forth.
We can also do a show NTP associations, press center, and
it can also show NTP associations detail, and
it'll give us a lot of the nitty gritty detail regarding that NTP association.
So there's the command right there, and
there's probably more than most people will ever need from the output. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
there's probably more than most people will ever need from the output.
And I want to change the time just to verify that our clients,
our three in this case, is going to follow this clock once again synchronizes.
So we'll do a clock set, and let's do 20 colon 18 colon.
Actually, you know what?
We could set it like a whole year off, but
let's just be aware that if we have a huge difference in time,
it may take a long time for that synchronization to catch up.
So let's go ahead and set it off for, let's say, I don't know how, 30 minutes.
Let's say 20, 48 colon, 0, 0, and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's say 20, 48 colon, 0, 0, and
let's keep the same date, October 16, 2024.
So now we do a show clock and show NTP status.
Because we're a stratum one device is just thinks, okay,
I'm going to trust my clock, whatever it is.
So it's trusting the clock that it's 20, 48.
And also I didn't change the local time zone with the offset.
So that's UTC time.
So if we go over to our three, who's synchronizing with R1,
we do a show NTP status and press enter, it's saying unsynchronized.
And that's because the time is different, and
it's going to take a little bit for it to sync up with the server. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
it's going to take a little bit for it to sync up with the server.
So we do a debug here of NTP all press enter, and
we can see the message is going back and forth.
All right, so we have some clock movement here.
Also, let me go ahead and change the interval as well as to a show run,
include NTP.
[LAUGH]
I said include, it should have been that,
should be voice recognition, include NTP config.
And I'll do an unall.
And let me go ahead and do it config T and the same command,
except I'm going to go ahead and change the timer, so
make it a little bit faster. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
make it a little bit faster.
So let's say min pull is four to the power four, and max pull is also
made to the power of four and first just for friends.
And that should make it happen a teeny bit faster.
So let's go ahead and do a show NTP status.
So boom, we are now synchronized with our stratum one server.
If we do a show NTP associations, we can confirm that.
Hence the little asterisk there to the left of our server.
And then we do a show clock on R1 and R3.
Let me go ahead and do it at the same time by using this icon up here.
So we'll do a show clock, and I'm going to send that to R1 and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we'll do a show clock, and I'm going to send that to R1 and
R3 at almost the exact same time with this tool here.
Then script and so it's 2052 here on R3 and R1, 20.
Okay, so it's slightly off, but you know what?
As we take a look at that offset, that offset is going to get less and
less as more packets go back and forth with NTP.
So if we do a show NTP associations, this offset should reduce itself over time
.
And actually I would like to see that.
So I'm going to go ahead and wait just a moment to show NTP associations again. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So I'm going to go ahead and wait just a moment to show NTP associations again.
And look at that, we now have less of an offset.
So if we went back and we did a show clock on both R1 and R3 at the same time,
they're going to be very, very close.
So their show clock on R3, 2053, 24, and we'll go to R1 and 2053, 16,
which is closer than it was a moment ago and as time goes on and
we give it a few more packs to go back and forth,
that synchronization actually should get closer and closer.
So the offset used to be minus 196 in milliseconds. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So the offset used to be minus 196 in milliseconds.
Now it's in 67 milliseconds.
All right, so let's take a look at our tasks.
So we set up R3 as an NTP client.
We set up R4 as NTP client R2.
And the next task here is to set R8 as an NTP client to server 1 nog.
And the reason I did this is I wanted to have you a little look and feel at
what NTP looks like when you have different vendors.
Because not every vendor influence NTP the same way.
And for example, a Windows server, as it gets time from the internet,
it has a certain stratum that it's using. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
it has a certain stratum that it's using.
So I thought it'd be useful to go ahead and see this.
So in our topology, that server, the server nog is right here.
Server 1 nog is at 192.168.1.100 in the bottom right of our topology.
It also happens to be the server that we're sitting at.
So if you go to a command prompt here on this server, any type in time,
and you press enter a couple times, it'll show us the local time.
And that's with a Pacific time zone offset.
So here on the Windows server, if we did a W32TM space/query,
space/status, this indicates that we're getting our time from this time server WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
space/status, this indicates that we're getting our time from this time server
out on the internet.
Here's the last successful sync time.
And here it shows us a stratum 5 server.
So if we are a client to this, we're not going to think stratum 5 is like the
cat's meow because stratum 1 and 2 or 3 is going to be way better.
But I'd like you to go ahead and be able to see that from the interface of a
Cisco
router that's trying to sync its time with this NTP server.
So let's go back to our terminal windows here.
This is a putty.
And in our task bus, it'd R8 to be an NTP client. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And in our task bus, it'd R8 to be an NTP client.
So in our topology, R8 is right here off this gig 00 interface connected to
that same subnet.
So let's go to the right router, R8, and we'll do a show NTP's status, great,
great, great.
And config T. And let's also actually do a ping of 192.168.1.100 to make sure
we can
get there.
Fantastic.
And let's go to config T and do a NTP server, 192.168.1.100.
And this is why it'd be useful to use certain options like version to specify
what version
of NTP want to use to be compatible with the server or to specify a key for WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
of NTP want to use to be compatible with the server or to specify a key for
authentication
if we're using authentication.
So I'm going to go ahead and say, let's do max poll, four and min poll of four.
And let's also go ahead and say burst.
And we'll say I burst.
Now I burst is if it's not reachable sending multiple requests.
But if it's reachable, the burst will cover that.
So let's go ahead and press enter.
And now that's done.
Let's do a show NTP status press enter.
So currently says unsynchronize, but check this out. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So currently says unsynchronize, but check this out.
It shows stratum six.
So we know we had some connectivity.
So we do a show NTP associations and press enter right here.
Check this out.
We have the tilde, which means we have full connectivity to that server.
And the AstroSki indicates that we are synchronizing with that server.
So currently here is our offset.
And if we do a show NTP status, eventually we should be synchronized.
Now look at this.
We were, it did show a stratum of six because the server was a stratum of five.
But now it's showing a stratum of 16. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But now it's showing a stratum of 16.
And this because it's still sorting it out, we haven't fully synchronized yet.
So in this case, we might need to let this sit for five or ten minutes as it
synchronizes.
Also if the clock on the NTP server is flapping or fluctuating or goes forward
and back and
forward and back is not considered reliable.
It could also cause this to take a long time before it's willing to synchronize
with that
destination.
So I'm going to hit the upper key and do a show NTP status.
And sure enough, it is not synchronized yet.
Now also if you have two servers and one is, for example, a stratum one and the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now also if you have two servers and one is, for example, a stratum one and the
other is
a stratum five, it's going to choose your router is going to choose the one
with the
better stratum.
So we could go in and we could say NTP server.
Let's pick on one, one, one, one.
And let's go ahead and say prefer and press enter.
Now even if we didn't use the prefer, it would still prefer one, one, one, one
because of
the lower stratum.
So in fact, let's go ahead and verify that by doing a no NTP server, one dot
one dot one
dot one, prefer and then with an NTP server, one dot one dot one and let's do a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
dot one, prefer and then with an NTP server, one dot one dot one and let's do a
burst.
And that looks great.
And it's also do a ping to one dot one dot one dot one.
Make sure we can get there and there's too many ones there.
That's why it didn't like that.
Sounds great.
We'll do a show NTP associations.
Now it shows us here that we have two configured, we have one, one, one, one
with full connectivity
and one 92, one state one dot one hundred shows us here that one, one, one, one
is a stratum
of one and the one and two, one state one dot one hundred is stratum of five.
And so once we synchronize, we're going to be synchronizing with the one with WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so once we synchronize, we're going to be synchronizing with the one with
the better
stratum, even though we didn't specify prefer.
So let's do a show NTP status and still not synchronized.
But again, we'll just give it a few moments and let it complete while that's
ticking.
Let's take a look at the rest of our tasks.
So the last part of our lab here was to set our three and our four as NTP peers
.
So we're waiting for our eight to synchronize.
Let's go ahead and set up our three and our four as NTP peers.
So we'll get our three first and our three, let's do a ping to four, four, four
, four,
we'll source that from our loopback zero just to make sure we have connectivity WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we'll source that from our loopback zero just to make sure we have connectivity
and we
do great.
So we'll go to configuration mode and say NTP here and we'll put in four, four,
four,
four, and we'll say source loopback zero.
That looks great.
And then we'll do similar treatment over on our four.
We'll show NTP associations and because our three made some requests in, we're
aware of
it, but we don't have it configured yet.
So let's go ahead and do a config T and we'll say NTP and we'll say 3, 3, 3, 3,
3 update
source loopback zero too much BGP. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
source loopback zero too much BGP.
I'll say source loopback zero, fantastic.
And then we'll do a show NTP associations.
And now we have a little tilde next to it because we now have it configured.
So notice that we lost our synchronization with 2, 2, 2, 2, but once it's
sourced everything
out, that should come back as well.
So let's go to our three and take a peek.
We'll do a show NTP associations and check it out.
So our three has re-synced up with 1111.
So if we did a show NTP status, we would expect to see synchronization with the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So if we did a show NTP status, we would expect to see synchronization with the
NTP server
and if we go to our four and let's see if our key show NTP associations, we
should not,
based on this output here, we should not yet expect to see synchronization.
So if we did a show NTP status and press dinner, it shows as unsynchronized.
However, that will correct itself in just a moment.
So while we're waiting, we can do a debug NTP all and we can just wait for a
message
indicating it's synchronized.
But right now we can confirm that we're communicating between 2, 2, 2, 2, and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But right now we can confirm that we're communicating between 2, 2, 2, 2, and
our loopback address
of 4, 4, 4, 4.
So we'll do a show NTP associations.
And once we have the little asterisk next to 2, 2, 2, 2, 2, that'll indicate
that we
have now synchronized with that server.
So our offset right now is huge.
And here we have a message here saying the clock is synchronized.
But if we do an undibogal, look at that for a moment, it shows as synchronized
with 3,
3, 3, 3, 3.
So now that it's settled, let's do a show NTP status and there we go.
So we are now synchronized with 2, 2, 2, 2, and if we do a show NTP WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we are now synchronized with 2, 2, 2, 2, and if we do a show NTP
associations and press
center, it now has the asterisk next to that guy and it's showing it correctly
as a stratum
level 2.
And 4, 3, 3, 3, 3, 3, it's still sorting it out because it's showing a stratum
16, which
isn't going to be correct for R3.
And the reason I wanted to have you do this lab is I wanted you to see
firsthand the fact
that sometimes it takes a while for NTP to configure.
By knowing a few of the show commands like show NTP status and show NTP
associations and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
associations and
show NTP associations detail, we can help identify what's going on and if we
need to,
throw in the debugs for NTP all so we can see exactly what's happening at a
very granular
level.
So thanks for joining me in this set of videos and I'll see you my friend in
the next one
soon.
Until then, I hope this has been informative and I'd like to thank you for
viewing.