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Let’s take a look at 15.2 clock and network time.
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We’re told to set the Branch 2 Router 3 system clock
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to the time zone of Central European Time,
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CET for short which is GMT+1
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and the daylight savings time and the daylight savings time
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We’re told to ensure that NTP is set up to synch the local clock
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to the PSTN router at IP address
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177.1.2.54.254
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and to ensure, sorry about the scroll there,
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and to ensure that the router can also serve
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NTP for SIP phones who later need it.
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So, the local Branch 2 Router 3
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but ensure that it does not become the primary synched clock for the router.
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This is the one that we’re gonna configure.
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We’ll do a show command but we’ll probably going to switch back out
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of the show command or should I say we’re not gonna sit here
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and wait for it to fully synchronize.
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So let’s do show clock and the time zone has been previously set.
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So, it’s still set that way because it updated hardware clock
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but let’s just go ahead and do clock time zone.
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It wants a name, give it whatever name we want.
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It’s not necessarily, it’s not checking anything.
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And we want +1 or we can just put in 1.
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If we want a negative value, then put in something like -5,
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and it would show us that it’s gonna change the clock.
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We’re actually gonna put in +1
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so it changed from 1919 hours to 1319
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and now it changed back from 13:19 to 19:19.
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And we’re also gonna say clock summer time
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and CEST and reoccurring.
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And it was already set to CEST.
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It was already running the Daylight Savings Time.
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Now, we wanna set up NTP and we wanna set up a master,
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sorry, we wanna set up NTP server
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pointed to, actually, let’s do a do show NTP associations first
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and we don’t see any or do show NTP status.
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NTP is not enabled.
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Just gonna bring this up to the top again.
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So, we’ll say NTP server 177.1.254.254.
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Now, if we say show association,
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we see that we got it configured and this little ~
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along with the legend of the bottom says that ~ is configured,
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but the * is at an actual system peer. So, in other words, we are synchronized.
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So, we’re still not synchronized, it’s configured.
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and the reference clock to the PSTN is still on initialization state.
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So, the stratum that said at 16 highest possible
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which is the worst possible value or the least trusted.
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So, after we’ve done some NTP talking back and forth,
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the reference clock of the PSTN will be updated
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to reflect with its reference clock is and its proper stratum.
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And then after that, we’ll go into an actual peering state.
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So for right now, we’re not gonna sit here and wait.
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We’ll say NTP, well, actually, it’s a bit difficult to do the NTP master
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if we don’t know what stratum the clock that we're gonna synch with this.
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And the reason is, whoever has the lowest stratum
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is the clock that the router will synch with.
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We need to do NTP master as we’ve talked about in Module 1.
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In order so that we can hand out time and we can serve,
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We, the Router 3 can serve NTP time which is what we were instructed to do.
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So, that later, zip phones could pull their time from us.
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So, we can just say NTP master, I'll take the default of 8
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or we can actually assign the stratum number.
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Now, we see that the PSTN address of 177.1.254.254
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has a reference clock of 127.127.7.1.
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Now, the entire 127/8 network was set aside for local loop backs.
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This is a local loop back to the PSTN router and we see it stratum 10.
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It's still disconfigured but obviously we received NTP information
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or else we wouldn’t have been updated with this information.
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It’s still not fully synched with our clock yet,
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but we can, now that we have the stratum, we can go ahead and say,
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If we just typed in NTP master, we would be able lower stratum
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and therefore more preferable with synch with ourselves
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and never synch with the PSTN which stopped trying to synchronized with it.
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So, we’re gonna say, let’s just say NTP Master 12, something higher.
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That’s actually gonna put our own internal master at 11.
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We’ll see that when we do a show NTP association.
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We see that we are 127.127.11, our reference clock is local.
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The stratum is 11, we put in 12 so the stratum is 11.
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We are 12 for whomever wants to get time from us.
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They will see our time is stratum 12,
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but we, ourselves, consider us 11.
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So this is why I put in 12 versus 11 which is only 1 higher
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then we would be 10 which is equal and we’ve synched with ourselves, well, probably.
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So, we’ll just go ahead and this is going to continue
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to try and synch up with the lower stratum which is the PSTN router.
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At some point, we’ll come back and we’ll see that little * there.
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But this will do it for right now.
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Let’s just do show NTP associations, still not synched.
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So, this is good enough for now and we’ll come back.
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