WEBVTT

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So with HSRP, Hot Standby Router Protocol, always remember for the exam we're using a Cisco proprietary protocol.

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So if the scenario is ever about having two multi-layer switches or two routers and they're different vendors, then HSRP is not what you're going to use.

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It's not going to be your answer. It's going to be VRRP in that particular case.

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So with HSRP now, what do we do?

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We are going to be creating groups for each and every single one of our subnets slash VLAN slash broadcast domains that we have.

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And we're going to be creating these. In this case, since it's multi-layer switches, we're going to be creating these groups on SVIs.

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So I'd go to, for example, interface VLAN 10 and do my configuration.

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All right. When we do the configuration and we set it up, for example, on this SVI and this SVI, we're going to get one active router for that group.

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One active router for that group. That is going to be the router with the highest priority.

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So this is based on priority. And the active router is going to be the one forwarding packets.

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It's going to be the one responding to ARP requests.

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It's also going to be sending and receiving hellos because it has to let the other routers in the group know that it is the active router.

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You got one standby router in your group.

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This is the router with the second highest priority amongst the routers in that group.

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It's going to send and receive hello packets.

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So that way there it can receive and learn about the active router.

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But it's also going to send because it wants the active router to know that it exists.

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But if there are other routers in the group because you can have more than two routers,

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you can have basically an unlimited number of routers in your group with HSRP.

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So, for example, you had three, four, five or six routers at the distribution layer for that,

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something which typically you want is typically only two.

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But if you had more and they were all interconnected, let's say we had another one here and it's connected up.

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It's connected up over here. It's connected up down here. It's connected up down here.

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Then, yeah, you can have all three in the group if you wanted to.

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So the standby router has to inform all the other ones.

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That's why it sends hellos as well.

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So it can inform the other routers in the group that, hey, I am a standby router.

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And it waits for the active router to fail so it can become the active router.

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And then if you do have extra routers, like I said, that are part of that group,

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then they're going to be what we call listeners.

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So they're not active. They're not standby.

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They're listeners because they're just listening for hello packets.

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Why? Because they want to know if there's already an active device.

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If there is, okay, then it looks for a standby device.

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Is there a standby device? Okay, yeah, then I'm just going to continue listening.

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So if all of a sudden the active device fails, the standby becomes active,

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and then a listener can become standby.

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So we have to go through different states in order to figure out who's active,

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who's standby, who's listener.

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Typically, you're only going to have active and standby.

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You'll never have listeners.

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But all the routers in the group, where they have two or more,

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are going to have to go through something called the listening state

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at some point in time, especially when they're initializing.

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So when we look here, in this particular case,

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we've got these different states listed.

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So obviously, if you're an active state, that means you're the active router.

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If you're in the standby state, you're the standby router.

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But when you initially enable this process, or if there's a failover that happens,

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the routers are going to have to go through different states.

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Now, if your standby failure happens, you immediately go active.

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You don't have to go back to the beginning and start over.

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But if I bring you up for the very first time as a router,

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or you've been rebooted, or anything like that,

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then you go to the initial state.

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It's the state as the start.

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It's when you've been configured for HSRP,

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or the interface has just been brought up, as an example.

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What if you bounce the interface, the SVI?

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You're in the initial state.

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From there, you go to the listening state.

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So you don't speak first.

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You listen first.

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You know the virtual router IP.

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You know the virtual router IP address because you've been configured with it.

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Therefore, you know the virtual router MAC address as well

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because it's automatically generated based on the fact you configured the IP address.

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So you're listening to see if there's anybody else out there already

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that is active or standby.

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If there's already an active standby device there,

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you stay in the listening state.

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But if there is no active or standby device out there,

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meaning you're not receiving hello packets,

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then you're going to move to the speak state.

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Now, if there's only an active device,

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then you're going to move to the speak state

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because you have a chance to become standby.

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But if there's an active and standby,

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you stay in the listening state.

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If there's nobody that's speaking right now,

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then you know that you have a chance to become active.

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So you're going to go speak.

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So what does speak mean?

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Now you're going to send your own hello messages.

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And you're going to actively participate in the election process

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of the active and standby router.

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So if you're the only one,

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then you're going to promote yourself to being active.

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If there's an active one there that's already active,

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depending on how you're configured,

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you might become active or you might go standby.

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So it all depends on the configuration you have,

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whether you move on or not,

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from standby to active and so on and so forth.

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So in the speaking state, you're doing your election.

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If you're standby, you become standby.

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If you determine you're active, you're active.

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So definitely make sure you understand these states

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and their definitions for the certification exam

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in case there's a drag and drop on the exam about all of these,

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or in case you have to answer a multiple choice question about these.

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Just want to make sure you're prepared.

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All right, let's go ahead and do some configurations now.

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And we're going to do it in our live environment.

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So I'm going to leave this diagram up so we can see it,

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but I'm going to do the exact config that you see there live.

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So first of all, let's go see PC number one.

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All right, PC number one right now.

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We'll see if we type in IP config.

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We'll see that PC number one.

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Let's try this again.

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I don't want this at the bottom.

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There you go.

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All right, so PC number one, 10.0.0.10, 255.255.255.0.

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With a default gateway of 10.0.0.254.

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So this is going to be the address we are going to use

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for HSRP in this particular case.

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So right now, let's go to DSW1.

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We'll type in configure terminal.

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And we're going to type in interface VLAN 10.

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And the commands for HSRP are standby.

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So there's a lot of different options we can have here.

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We're definitely going to not cover all of them,

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but we're going to focus on the ones we need to know

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for the certification exam.

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But one thing you want to know here is that

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the group number does not have to be entered.

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If you don't enter the group number,

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it defaults to zero.

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I repeat that.

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If you don't configure the group number,

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it defaults to zero.

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Why is that important?

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Because if you are on the exam,

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and you have to configure HSRP

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according to their instructions,

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if you forget the group number,

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you configure it for zero by accident.

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It doesn't give you an error.

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It automatically does it for group zero.

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And the last thing you want to do is do an entire config.

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And for you, it's working fine.

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But in the end, when the system grades it,

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you use the wrong group number.

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And guess what?

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You get zero.

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That's not what you want to have happen.

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So be careful with that.

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So the group number can be anything you want it to be.

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It doesn't have to match your VLAN.

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It doesn't have to match your subnet.

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It can be anything you want it to be.

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From zero to 255.

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So I'm going to use 10.

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Just because I want to.

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And it has nothing to do with this being interface VLAN 10.

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It has nothing to do with this going to be part of my VLAN 10 subnet.

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No, I'm just using it because I want to.

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On the exam,

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they don't tell you what group number to use.

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And you can use whatever you want.

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But if they tell you a group number to use,

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make sure you use it.

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If they tell you a group number to use,

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make sure you use that group number.

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Now, maybe also remember this.

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The group number has to match.

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So if they already have one device configured,

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and they're asking you to do the other device,

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what does that mean?

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You're going to have to verify the group number on the other device.

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And maybe even the IP address.

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What if they don't give you any details,

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and you have to find them on the other device?

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So you're going to be looking for the IP.

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You're going to be looking for that group number.

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All those things have to match in this config.

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Now, once I type in my group number,

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I am then going to type in IP,

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because this is the most fundamental command you need to get it turned on.

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Standby, then the group number, then the word IP.

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And then you put the IP address in that you want to use.

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So remember this IP address we had here?

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That's the IP address we're giving to the PC.

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So what did we say we were using on our PC?

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We said we were using 10.0.0.254.

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So that's the one we want.

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10.0.0.254.

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That's it, done.

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Hit enter.

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So that is like the basic command.

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That's it, that's all.

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Now, is it going to work the way I want it to work,

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the way I like it to work?

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No, because there's a lot more I have to teach you,

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and a lot more that's going to be on the certification exam

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when it comes to HSRP.

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So right now it's going through the states,

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the states that we talked about a while ago.

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So right now it's more than likely in the speak state,

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and now it's in the active state.

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So I am the active device.

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Now, if we type in do show IP, no, do show standby,

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we'll see here that for, be careful with this,

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interface VLAN10.

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That's what that means.

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That's the interface name and number.

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Because if we were doing this on a router interface,

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it would actually have the router interface listed there,

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like gigabitethernet00.

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So that doesn't mean VLAN10.

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That means interface VLAN10.

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We are part of group 10 because of this command right here.

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And the virtual IP address is 10.0.0.0.254

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because we typed in this command here.

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It says that I am the active device,

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and we can confirm that with this syslog message right here.

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What else?

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There is the virtual MAC address.

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The virtual MAC address.

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And so how was this generated?

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This is going to be important for you.

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So we have 0.0.0.0.0C07AC08.

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That's the MAC address.

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How was this determined?

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Well, this is Cisco's OUI.

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So that was given to Cisco by the IEEE.

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For use as what?

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MAC addressing.

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OUI, Organizational Unique Identifier for MAC addressing.

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All right?

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07AC means HSRP version number one.

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0A, this is your group number.

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Group number.

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That is the group number.

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In what?

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Hexadecimal.

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Hexadecimal.

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So notice how this is the exact same MAC address that is right there.

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Why?

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HSRP version number one.

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And it's what?

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Group number 10.

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So how does that group number come about?

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Well, if you don't know how hex works, every single hex character is four binary bits.

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So 0, for example, would equal what?

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0.0.0.0.

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And A, well, if you remember, hex goes from 0 to 9 and then A, B, C, D, E, F.

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Well, A is equal to what?

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A is equal to 10.

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So what is A in binary?

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Well, if it's 10, if you remember 128, 64, 32, 16, 8, 4, 2, 1 from your CCNA days,

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we are just dealing with these four right now.

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So 10 would be 8 plus 2, and there you go.

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So now when you combine it all together, what do you have?

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You have 0, 0, 0, 0, 1, 0, 1, 0.

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Okay, what does all of that equal?

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All of that equals 10.

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All of that equals 10.

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So let's say we had group 20.

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What would group 20 be?

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Okay, well, the best way to do that right now to test it is let's type in interface VLAN 20,

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and let's say standby 20, and we are in 2.

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All right, now let's take a look at do show standby again,

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and you'll see where this can get very, okay.

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Right now it's still going through the election process, but we'll grab that right there.

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So it's 14.

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It's 14.

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So let me write that out for all of us, or I'll just erase this stuff here.

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All right, and I'll show you how to calculate that one.

00:14:00.000 --> 00:14:01.000
So 14.

00:14:01.000 --> 00:14:07.000
So you got to be careful with this, because if I asked you right now which group is this,

00:14:07.000 --> 00:14:11.000
which group is this, if you say 14, you are wrong.

00:14:11.000 --> 00:14:13.000
Right, Conrad?

00:14:17.000 --> 00:14:19.000
If you say 14, you're wrong.

00:14:19.000 --> 00:14:22.000
Right, Conrad?

00:14:22.000 --> 00:14:27.000
Conrad says memorizing all the virtual MAC addresses for the first hopper density protocol is the most annoying part of CCNA.

00:14:27.000 --> 00:14:29.000
Exactly, right, and that's the struggle.

00:14:29.000 --> 00:14:32.000
We're going to get tested on that here in Encore as well.

00:14:32.000 --> 00:14:34.000
So 14 is what?

00:14:34.000 --> 00:14:38.000
Well, 1 equals 0001.

00:14:38.000 --> 00:14:40.000
4 equals 0100.

00:14:40.000 --> 00:14:41.000
Now put it all together.

00:14:41.000 --> 00:14:44.000
You get 0001, 0100.

00:14:44.000 --> 00:14:46.000
Now figure out what they are.

00:14:46.000 --> 00:14:50.000
So you'd have 128, 64, 32, 16.

00:14:50.000 --> 00:14:53.000
So we have 16 plus 8.

00:14:54.000 --> 00:15:08.000
Oh, 4, 16, 8, 4, 2.

00:15:08.000 --> 00:15:09.000
I'm looking at it.

00:15:09.000 --> 00:15:10.000
I'm like, that doesn't make sense.

00:15:10.000 --> 00:15:12.000
There you go, 20.

00:15:12.000 --> 00:15:13.000
20.

00:15:13.000 --> 00:15:14.000
Group 20.

00:15:14.000 --> 00:15:16.000
Group 20.

00:15:24.000 --> 00:15:28.000
One more, just to show you.

00:15:28.000 --> 00:15:35.000
We have interface VLAN 50, right?

00:15:35.000 --> 00:15:39.000
Let's say you're group 50.

00:15:40.000 --> 00:15:43.000
It ends in 32 now.

00:15:43.000 --> 00:15:47.000
So look, group 50 is actually 32.

00:15:47.000 --> 00:15:53.000
So again, which group is this?

00:15:53.000 --> 00:15:56.000
It's not group 32.

00:15:56.000 --> 00:15:59.000
You've got to be mindful of that, right?

00:15:59.000 --> 00:16:02.000
We're dealing with virtual MAC addresses.

00:16:03.000 --> 00:16:05.000
It's not group 32.

00:16:05.000 --> 00:16:08.000
You've got to be mindful of that, right?

00:16:08.000 --> 00:16:09.000
We're dealing with which group?

00:16:09.000 --> 00:16:12.000
Well, you're going to have to take the first value of 3.

00:16:12.000 --> 00:16:16.000
That's going to be 0011.

00:16:16.000 --> 00:16:19.000
And then you have 2, which is 0010.

00:16:19.000 --> 00:16:24.000
Now put them together, 0011, 0010.

00:16:24.000 --> 00:16:26.000
So you've got 128, 64.

00:16:26.000 --> 00:16:30.000
You've got 32, 16, and 2.

00:16:31.000 --> 00:16:34.000
So that's 48 plus 2 is 50.

00:16:34.000 --> 00:16:36.000
There you go.

00:16:36.000 --> 00:16:39.000
So yes, is this something you might want to be able to do?

00:16:39.000 --> 00:16:42.000
Sure, because if you can do the simple math,

00:16:42.000 --> 00:16:45.000
then that means you'll always get those questions right.

00:16:46.000 --> 00:16:48.000
So that's how the MAC address is created.

00:16:48.000 --> 00:16:54.000
It's just dynamically generated using Cisco's OUI, 07AC,

00:16:54.000 --> 00:16:57.000
and then the group number that you created.

00:16:57.000 --> 00:17:00.000
So as you've seen so far, we have created groups for VLAN,

00:17:00.000 --> 00:17:02.000
for interface VLAN 50.

00:17:02.000 --> 00:17:05.000
We've created groups for interface VLAN 60.

00:17:05.000 --> 00:17:08.000
We've created groups for interface VLAN 60.

00:17:08.000 --> 00:17:11.000
We've created groups for interface VLAN 60.

00:17:11.000 --> 00:17:14.000
And as you've seen so far, we have created groups for VLAN,

00:17:14.000 --> 00:17:17.000
for interface VLAN 50, interface VLAN 20,

00:17:17.000 --> 00:17:21.000
and interface VLAN 10.

00:17:21.000 --> 00:17:24.000
Now, let's go to ASW1 right now.

00:17:24.000 --> 00:17:26.000
You're welcome, Conrad.

00:17:26.000 --> 00:17:28.000
Let's go to ASW1 right now, because remember what we said.

00:17:28.000 --> 00:17:30.000
When you become active, you're going to send out what?

00:17:30.000 --> 00:17:31.000
What is it called?

00:17:31.000 --> 00:17:32.000
A GARP, a gratuitous ARP.

00:17:32.000 --> 00:17:38.000
So let's take a look at our MAC address.

00:17:38.000 --> 00:17:39.000
What do we see?

00:17:39.000 --> 00:17:42.000
07AC in here right now.

00:17:42.000 --> 00:17:43.000
There it is.

00:17:43.000 --> 00:17:50.000
So there's the one for VLAN 20, AC14, right?

00:17:50.000 --> 00:17:52.000
It ended in 14, we said.

00:17:52.000 --> 00:17:54.000
We should have one for VLAN 10 here.

00:17:54.000 --> 00:17:55.000
There it is.

00:17:55.000 --> 00:17:56.000
There's the one for VLAN 10.

00:17:56.000 --> 00:18:00.000
We said it ended in 0A.

00:18:00.000 --> 00:18:04.000
And then we should have the other one that we just did for VLAN 50,

00:18:04.000 --> 00:18:06.000
AC32.

00:18:06.000 --> 00:18:12.000
There it is right there.

00:18:12.000 --> 00:18:16.000
Now, here's a prime example of suboptimal routing

00:18:16.000 --> 00:18:18.000
or suboptimal switching.

00:18:18.000 --> 00:18:28.000
So right now for VLAN 10, DSW1 is the root bridge for VLAN 10,

00:18:28.000 --> 00:18:33.000
and it's also my active forwarder because we configured on DSW1.

00:18:34.000 --> 00:18:42.000
So notice in this output, gigabit 1 slash 0 slash 45 to get there.

00:18:42.000 --> 00:18:44.000
That makes perfect sense.

00:18:44.000 --> 00:18:53.000
What I want to point out to you right now, though, is, for example, this one.

00:18:53.000 --> 00:18:56.000
This right now is the active forwarder.

00:18:56.000 --> 00:18:59.000
It's the default gateway, but this is the root bridge.

00:18:59.000 --> 00:19:03.000
This is the root bridge right now for VLAN 20.

00:19:03.000 --> 00:19:06.000
Look what port it's sending it out of.

00:19:06.000 --> 00:19:07.000
Why?

00:19:07.000 --> 00:19:12.000
Because this is the root port right now for VLAN 20.

00:19:12.000 --> 00:19:20.000
So now the traffic actually for VLAN 20 would go bloop, bloop, bloop, bloop,

00:19:20.000 --> 00:19:22.000
which I said you don't want to do, right?

00:19:22.000 --> 00:19:23.000
That's why it's so important.

00:19:23.000 --> 00:19:25.000
You're seeing it right here now, live,

00:19:25.000 --> 00:19:29.000
that if you're not mindful of how traffic flows with Spanning Tree Protocol,

00:19:29.000 --> 00:19:38.000
you could have suboptimal forwarding based on other things you've configured.

00:19:38.000 --> 00:19:41.000
So now the question is, do we modify Spanning Tree Protocol,

00:19:41.000 --> 00:19:45.000
or do I make this one the active forwarder for VLAN 20?

00:19:45.000 --> 00:19:49.000
More than likely, depending on my environment, I might have VLAN 10 going this way,

00:19:49.000 --> 00:19:53.000
20 going this way, maybe 200 going this way, maybe 50 going this way.

00:19:54.000 --> 00:19:55.000
It depends on what you want.

00:19:55.000 --> 00:19:59.000
Just make sure you configure it properly based on how you want traffic to flow.

00:19:59.000 --> 00:20:05.000
You need to be in control, and that's Spanning Tree Protocol, right?

00:20:05.000 --> 00:20:06.000
Now what does that mean?

00:20:06.000 --> 00:20:17.000
It means if we go to our PC again, we should be able to see in our ARP cache 10.0.0.254,

00:20:17.000 --> 00:20:21.000
and there it is, and there's the MAC address.

00:20:21.000 --> 00:20:25.000
So at some point, PC1 sent out an ARP request,

00:20:25.000 --> 00:20:30.000
and DSW1 responded back with the reply, and it gave me my MAC address.

00:20:30.000 --> 00:20:32.000
So let's go ahead and do a ping.

00:20:32.000 --> 00:20:42.000
Let's ping to the default gateway.

00:20:42.000 --> 00:20:45.000
And you'll see that I'm getting a response from who?

00:20:45.000 --> 00:20:48.000
That's going to be from PC number one.

00:20:48.000 --> 00:20:51.000
Sorry, DSW1.

00:20:51.000 --> 00:20:57.000
DSW1 is the one who's responding back to me because it is the active forwarder.

00:20:57.000 --> 00:21:01.000
Let's ping somewhere else in the environment.

00:21:01.000 --> 00:21:02.000
Let's see.

00:21:02.000 --> 00:21:14.000
Could I do 8.8.8.8?

00:21:14.000 --> 00:21:18.000
That is because I probably don't have one of my routers set up properly.

00:21:18.000 --> 00:21:19.000
Let's go to branch right now.

00:21:19.000 --> 00:21:20.000
What's the IP address?

00:21:20.000 --> 00:21:22.000
10.50.12.

00:21:22.000 --> 00:21:24.000
10.50.12.129.

00:21:24.000 --> 00:21:27.000
Let's use that address because I'm pretty sure I can reach that one right now.

00:21:27.000 --> 00:21:35.000
10.50.12.129.

00:21:35.000 --> 00:21:36.000
There you go.

00:21:36.000 --> 00:21:39.000
All right, so but the question is, is who am I going through?

00:21:39.000 --> 00:21:43.000
One of the greatest ways we can test that is do a trace to that address.

00:21:43.000 --> 00:21:53.000
So, if we do 10.50.12.129, we'll see from the response which router we're actually going through.

00:21:53.000 --> 00:21:58.000
So, if I can see here 10.0.0.1, then I know I'm going through DSW1.

00:21:58.000 --> 00:22:01.000
So, that's how you can confirm it in the real world and on the certification exam.

00:22:01.000 --> 00:22:03.000
Is HSRP working the way I want it to?

00:22:03.000 --> 00:22:05.000
Is VRRP working the way I want it to?

00:22:05.000 --> 00:22:06.000
Is GLPV working?

00:22:06.000 --> 00:22:12.000
Use a trace to any address beyond because then you'll see what default gateway you're going through.

00:22:12.000 --> 00:22:25.000
All right, let's go ahead now and set up DSW2 for interface VLAN10 because we've only done one so far, right?

00:22:25.000 --> 00:22:32.000
So, interface VLAN10, let's now type in standby.

00:22:32.000 --> 00:22:34.000
And what's our group?

00:22:34.000 --> 00:22:36.000
Our group number we said for this one was group 10.

00:22:36.000 --> 00:22:38.000
And what's our IP?

00:22:38.000 --> 00:22:40.000
10.0.0.254.

00:22:40.000 --> 00:22:44.000
And it's so important that you get the numbers matching 100%.

00:22:44.000 --> 00:22:52.000
If they don't match 100% between DSW1 and DSW2 for interfaces that are in the exact same subnet, then it's not going to work.

00:22:52.000 --> 00:22:55.000
So, things to pay attention to on the exam are what?

00:22:55.000 --> 00:22:59.000
Are the group numbers the same on the interfaces in the same subnet?

00:22:59.000 --> 00:23:03.000
Are the IP addresses the same on the interfaces in the same subnet?

00:23:03.000 --> 00:23:05.000
So, interface VLAN10 and interface VLAN10.

00:23:05.000 --> 00:23:06.000
So, what does that mean?

00:23:06.000 --> 00:23:13.000
Could Cisco also accidentally give you a scenario or a question where it's interface VLAN10 here, but interface VLAN20 here,

00:23:13.000 --> 00:23:21.000
and they put the wrong IP address and the wrong group number or the right IP address and the right group number on different interfaces?

00:23:21.000 --> 00:23:23.000
Yeah, they could do that.

00:23:23.000 --> 00:23:25.000
And you've got to recognize that that's not going to work.

00:23:25.000 --> 00:23:29.000
It's got to be two interfaces in the same subnet.

00:23:29.000 --> 00:23:33.000
So, interface VLAN10, interface VLAN10 are in the same subnet.

00:23:33.000 --> 00:23:38.000
But if they did interface VLAN10, interface VLAN20, and then put that addressing information on it, there's your problem.

00:23:42.000 --> 00:23:48.000
Now, you shouldn't be able to, let me check, you shouldn't be able to give it an IP address that's not in its actual subnet.

00:23:48.000 --> 00:23:49.000
You see?

00:23:49.000 --> 00:23:51.000
It says right there you can't do that.

00:23:51.000 --> 00:24:03.000
But does that stop Cisco from doing copying and pasting and a little bit of Photoshopping and a multiple choice question to see if you understand that it has to be an interface in the same subnet?

00:24:03.000 --> 00:24:05.000
It has to be the same group number.

00:24:05.000 --> 00:24:06.000
It has to be.

00:24:06.000 --> 00:24:08.000
No, it doesn't stop them, right, from Photoshopping.

00:24:08.000 --> 00:24:09.000
So, always be mindful of that.

00:24:09.000 --> 00:24:14.000
Even though we know certain things could never happen in the real world, it doesn't stop Cisco from Photoshopping.

00:24:21.000 --> 00:24:22.000
All right.

00:24:22.000 --> 00:24:29.000
So, I got the interfaces in the same subnet, and I have the same group number, and I've got the same IP address.

00:24:33.000 --> 00:24:39.000
Now, something to keep in mind here is that I already have an active device right now.

00:24:41.000 --> 00:24:43.000
I already have an active device right now.

00:24:44.000 --> 00:24:47.000
So, we are having an election right now.

00:24:48.000 --> 00:24:50.000
And notice I went standby.

00:24:51.000 --> 00:24:54.000
So, how does the election process actually work?

00:24:55.000 --> 00:24:56.000
What decided that that was active?

00:24:56.000 --> 00:24:58.000
What decided that that was standby?

00:24:59.000 --> 00:25:01.000
So, here's how the election process works.

00:25:02.000 --> 00:25:04.000
Number one, it's based on priority.

00:25:04.000 --> 00:25:11.000
So, if I type in do show standby, what is my priority?

00:25:13.000 --> 00:25:16.000
My priority is 100 on DSW2.

00:25:20.000 --> 00:25:21.000
Let's go to DSW1.

00:25:22.000 --> 00:25:23.000
Do show standby.

00:25:24.000 --> 00:25:28.000
What is my priority for interface VLAN10?

00:25:28.000 --> 00:25:30.000
It is 100.

00:25:31.000 --> 00:25:35.000
So, whoever has the higher priority becomes the active router.

00:25:37.000 --> 00:25:39.000
Well, our priority is tied.

00:25:39.000 --> 00:25:40.000
Our priority is tied.

00:25:41.000 --> 00:25:43.000
So, what breaks the tie?

00:25:45.000 --> 00:25:59.000
The tie is going to be broken by the device, or the tie is going to be broken with the higher interface IP address.

00:26:00.000 --> 00:26:07.000
Meaning that whoever has the higher interface IP address becomes the active forwarder.

00:26:07.000 --> 00:26:17.000
So, DSW2 has the IP address 10.0.0.2, and DSW1 has the IP address 10.0.0.1.

00:26:18.000 --> 00:26:21.000
Which one's higher, DSW2 or DSW1?

00:26:24.000 --> 00:26:25.000
Chat in.

00:26:28.000 --> 00:26:29.000
Not sure what question.

00:26:34.000 --> 00:26:36.000
Yep, it's DSW2.

00:26:37.000 --> 00:26:45.000
So, DSW2 has the higher IP address, so it should be the active device.

00:26:46.000 --> 00:26:54.000
And we can see in our output that DSW1 is active and DSW2 is standby.

00:26:55.000 --> 00:27:03.000
So, basically what I just told you is true, but my devices are calling me a liar.

00:27:03.000 --> 00:27:05.000
What I just told you is true.

00:27:06.000 --> 00:27:14.000
Higher priority, and if the priors are tied, then the higher IP address is the winner.

00:27:15.000 --> 00:27:17.000
Well, not according to my devices.

00:27:19.000 --> 00:27:20.000
Why?

00:27:21.000 --> 00:27:22.000
Why?

00:27:24.000 --> 00:27:34.000
Because by default we are non-preemptive.

00:27:35.000 --> 00:27:38.000
You'll see here that it says preemption is disabled.

00:27:38.000 --> 00:27:40.000
What does that mean?

00:27:41.000 --> 00:27:49.000
It means that if someone is already active, they remain active no matter what.

00:27:51.000 --> 00:27:55.000
So, even if DSW2 has a higher priority, it doesn't matter.

00:27:56.000 --> 00:28:00.000
If DSW1's already active, it stays active.

00:28:03.000 --> 00:28:08.000
Even if DSW2 has a higher IP address, doesn't matter.

00:28:09.000 --> 00:28:15.000
If DSW1's already active, it stays active because it's non-preemptive.

00:28:16.000 --> 00:28:19.000
HSRP by default.

00:28:20.000 --> 00:28:35.000
So, if you want to be able to control who is always the active forwarder under normal operating conditions, you will have to turn preemption on.

00:28:37.000 --> 00:28:42.000
So, for example, if right now we force a failure.

00:28:42.000 --> 00:28:46.000
So, let's just say interface VLAN10.

00:28:46.000 --> 00:28:49.000
Let's just shut down interface VLAN10 just really quickly.

00:28:50.000 --> 00:28:52.000
That's going to cause a failover to happen.

00:28:52.000 --> 00:29:00.000
So, we should see DSW2 is going to become active for interface VLAN10 or group 10, I should say.

00:29:01.000 --> 00:29:02.000
You can see it's now active.

00:29:03.000 --> 00:29:09.000
And if we want to test that with our PC, if we just simply do a trace, we'll see that we're now going through DSW2.

00:29:09.000 --> 00:29:10.000
That's perfect.

00:29:10.000 --> 00:29:11.000
There you go.

00:29:11.000 --> 00:29:13.000
DSW2 10.0.0.2.

00:29:16.000 --> 00:29:28.000
But now, if we go back to DSW1 and we re-enable it, is DSW1 going to become active or is it going to go to standby?

00:29:29.000 --> 00:29:30.000
Okay.

00:29:30.000 --> 00:29:36.000
Well, because preemption is off, we will go standby because there's already somebody who's active.

00:29:36.000 --> 00:29:37.000
That's what it means.

00:29:37.000 --> 00:29:41.000
If preemption is disabled, like it is, you can see it right there.

00:29:41.000 --> 00:29:51.000
If preemption is disabled, it means that if somebody's already active, you cannot become active, no matter what, even if you have a higher priority.

00:29:52.000 --> 00:29:53.000
So, you can see I'm standby now.

00:29:53.000 --> 00:30:01.000
So, even if I said standby 10 priority, let's change the priority to 110 on DSW1.

00:30:02.000 --> 00:30:05.000
And we'll look at the output of do show standby right now.

00:30:06.000 --> 00:30:14.000
We'll see here that I have a priority of 110 and DSW2 has a priority of 100.

00:30:14.000 --> 00:30:16.000
It doesn't matter.

00:30:16.000 --> 00:30:17.000
Why?

00:30:17.000 --> 00:30:18.000
Preemption.

00:30:19.000 --> 00:30:21.000
Preemption says what?

00:30:21.000 --> 00:30:24.000
Preemption says DSW2's active.

00:30:24.000 --> 00:30:26.000
It will remain active until it fails.

00:30:26.000 --> 00:30:27.000
DSW2's active.

00:30:27.000 --> 00:30:29.000
It will remain active until it fails.

00:30:31.000 --> 00:30:41.000
So, how can I turn around and force DSW1 to always be, always be the active device under normal conditions?

00:30:41.000 --> 00:30:46.000
Well, one, give it a higher priority like we already have done.

00:30:46.000 --> 00:30:49.000
And two, turn on preemption.

00:30:49.000 --> 00:30:53.000
So, standby 10 preempt.

00:30:53.000 --> 00:30:54.000
Done.

00:30:54.000 --> 00:31:02.000
Now, because I have the higher priority and preemption is enabled, I become the active device.

00:31:19.000 --> 00:31:22.000
Three really important commands you need to know for the exam.

00:31:22.000 --> 00:31:31.000
Oh, and by the way, if you accidentally type standby preempt and you forgot the 10, guess what that would configure it for?

00:31:33.000 --> 00:31:34.000
Right?

00:31:34.000 --> 00:31:39.000
If you accidentally did this, you see?

00:31:39.000 --> 00:31:47.000
So, if you accidentally forgot the 10 on the exam, then you would actually be configuring it for zero and it would not actually work.

00:31:48.000 --> 00:31:49.000
Right?

00:31:49.000 --> 00:31:52.000
So, make sure you don't forget the group number.

00:31:52.000 --> 00:32:02.000
So, from a personal experience, folks, preemption should always be on, no matter what.

00:32:02.000 --> 00:32:10.000
Because momentarily, we're going to show you some additional failover features with HSRP.

00:32:10.000 --> 00:32:15.000
And the only way they're going to work is if preemption is on anyways.

00:32:16.000 --> 00:32:24.000
I have always believed it should be something that is on, but I feel like they have it off by default so they can make the exam harder.

00:32:28.000 --> 00:32:30.000
So, I am going to turn it on over here as well.

00:32:30.000 --> 00:32:32.000
Standby 10.

00:32:32.000 --> 00:32:34.000
And that is not a joke.

00:32:34.000 --> 00:32:35.000
I'm serious, all right?

00:32:35.000 --> 00:32:38.000
Because the odds of them testing you on preemption is going to be high.

00:32:41.000 --> 00:32:42.000
Why?

00:32:42.000 --> 00:32:44.000
It's been that way for years.

00:32:45.000 --> 00:32:46.000
Years.

00:32:49.000 --> 00:32:53.000
So, here is the standby device.

00:32:53.000 --> 00:32:54.000
So, I'm forcing, right?

00:32:54.000 --> 00:32:56.000
I'm forcing DSW-2 to be standby.

00:32:56.000 --> 00:32:58.000
I'm forcing DSW-1 to be active.

00:32:58.000 --> 00:33:02.000
So, here's a good starting standby configuration.

00:33:02.000 --> 00:33:06.000
Here's a good starting active configuration.

00:33:06.000 --> 00:33:08.000
Just keep that in mind.

00:33:08.000 --> 00:33:11.000
So, remember, if priority is not listed, it means your priority is 100.

00:33:12.000 --> 00:33:14.000
So, here, priority is not listed.

00:33:14.000 --> 00:33:15.000
It's 100.

00:33:15.000 --> 00:33:17.000
Priority is listed.

00:33:17.000 --> 00:33:18.000
It's not 100.

00:33:20.000 --> 00:33:21.000
All right.

00:33:21.000 --> 00:33:26.000
So, let's go ahead now and do a continuous ping on our PC.

00:33:26.000 --> 00:33:27.000
Got too many mice here.

00:33:27.000 --> 00:33:29.000
I'm grabbing the wrong mouse.

00:33:29.000 --> 00:33:30.000
All right.

00:33:30.000 --> 00:33:31.000
So, let's do a continuous ping.

00:33:36.000 --> 00:33:40.000
To 10.50.12.129.

00:33:42.000 --> 00:33:45.000
Forget how to do a continuous ping here.

00:33:47.000 --> 00:33:48.000
There you go.

00:33:48.000 --> 00:33:49.000
Minus 10.

00:33:49.000 --> 00:33:50.000
Perfect.

00:33:59.000 --> 00:34:00.000
All right.

00:34:00.000 --> 00:34:06.000
So, we have the ping going, and it's got a timeout value of not timeout, but every two seconds.

00:34:06.000 --> 00:34:07.000
One, two.

00:34:07.000 --> 00:34:08.000
Yeah, every two seconds.

00:34:08.000 --> 00:34:09.000
Right?

00:34:09.000 --> 00:34:10.000
All right.

00:34:10.000 --> 00:34:11.000
So, we'll let that run.

00:34:11.000 --> 00:34:17.000
Now, what we're going to do is we are going to go to DSW1, and then we're going to just

00:34:17.000 --> 00:34:23.000
type an interface range gigabit Ethernet 1 slash 0 slash 17 through 24.

00:34:23.000 --> 00:34:27.000
Let's just go ahead and shut down all these interfaces.

00:34:27.000 --> 00:34:31.000
And what we're going to do is we're just going to go over to the PC, and we're going to see

00:34:31.000 --> 00:34:33.000
how many packets go missing.

00:34:39.000 --> 00:35:04.000
Not too bad.

00:35:04.000 --> 00:35:05.000
I mean, what?

00:35:05.000 --> 00:35:07.000
Failover happened in my case relatively quickly.

00:35:07.000 --> 00:35:10.000
Only lost a packet or two, maybe.

00:35:15.000 --> 00:35:21.000
Obviously, your end stations would be transmitting a significantly greater number of packets

00:35:21.000 --> 00:35:33.000
in a two-second timeframe, but, you know, that's a nice failover using just default

00:35:33.000 --> 00:35:34.000
timers.

00:35:34.000 --> 00:35:36.000
And we can definitely get it quicker.

00:35:36.000 --> 00:35:44.000
Now, let's bring all these interfaces back up, and we'll see if we type in no shut.

00:35:44.000 --> 00:35:57.000
And we'll just come back here.

00:35:57.000 --> 00:36:00.000
So, I lost one failing back over as well.

00:36:00.000 --> 00:36:01.000
So, that would have been what?

00:36:01.000 --> 00:36:04.000
Spanning sheet protocol having to converge potentially.

00:36:04.000 --> 00:36:08.000
And during that convergence, one of the packets just simply didn't make it through when it

00:36:08.000 --> 00:36:10.000
was all said and done.

00:36:10.000 --> 00:36:11.000
But there you go.

00:36:11.000 --> 00:36:15.000
There is an example of being able to failover from one device to another device in your

00:36:15.000 --> 00:36:19.000
default gateway, and your client only has to worry about being configured with one of

00:36:20.000 --> 00:36:34.000
All right.

00:36:34.000 --> 00:36:36.000
Let's just take a peek at some of our slides now.

00:36:36.000 --> 00:36:40.000
So, our slides, I do have the configs for you if you ever want to go back and review

00:36:40.000 --> 00:36:41.000
them.

00:36:41.000 --> 00:36:48.000
That's DSW2's config.

00:36:49.000 --> 00:36:52.000
And then we've already seen this output here so far.

00:36:52.000 --> 00:36:54.000
So, we understand the MAC address.

00:36:54.000 --> 00:36:56.000
We understand the virtual IP now.

00:36:56.000 --> 00:36:59.000
We understand preemption enabled versus disabled.

00:36:59.000 --> 00:37:00.000
We know who's active.

00:37:00.000 --> 00:37:02.000
We know who's standby.

00:37:02.000 --> 00:37:08.000
So, we've got you covered there so far.

00:37:08.000 --> 00:37:12.000
So, let's talk about failover now.

00:37:13.000 --> 00:37:22.000
So, right now, the scenario I provided to you is based on what?

00:37:22.000 --> 00:37:31.000
It's based on DSW1 and DSW2 being able to communicate with each other inside the subnet

00:37:31.000 --> 00:37:33.000
VLAN broadcast domain.

00:37:33.000 --> 00:37:40.000
So, DSW1 and DSW2 are sending hello packets back and forth in that environment to each

00:37:40.000 --> 00:37:49.000
other using the multicast address 224002 for HSRP version 1.

00:37:49.000 --> 00:37:56.000
And they're doing that every three seconds with a dead timer of ten seconds by default.

00:37:56.000 --> 00:37:59.000
And we can verify those timers in our config.

00:37:59.000 --> 00:38:09.000
If we type in do show standby, you'll see the default timers are three and ten.

00:38:09.000 --> 00:38:20.000
So, if all of a sudden something happens to DSW1, then that means there will no longer

00:38:20.000 --> 00:38:26.000
be the hello packet coming from DSW1.

00:38:26.000 --> 00:38:35.000
So, DSW2 within ten seconds will recognize that and promote itself to active.

00:38:36.000 --> 00:38:40.000
And as we talked about, send out the GARP and everything else in our previous discussion.

00:38:40.000 --> 00:38:42.000
So, now traffic flows this way.

00:38:42.000 --> 00:38:45.000
So, that's what I just demoed to you.

00:38:45.000 --> 00:38:48.000
That's what is happening.

00:38:48.000 --> 00:38:55.000
So, it's the absence of hello packets that are causing the failover to occur because

00:38:55.000 --> 00:38:57.000
of the failure.

00:38:57.000 --> 00:39:02.000
So, the failure of the SVI or the failure of the physical interfaces.

00:39:02.000 --> 00:39:08.000
So, as long as one physical interface is still up that has the ability to send hello packets,

00:39:08.000 --> 00:39:12.000
technically DSW1 would still remain active, right?

00:39:12.000 --> 00:39:14.000
Yeah.

00:39:14.000 --> 00:39:19.000
So, it's just simply based on the fact that hello packets cease to exist.

00:39:19.000 --> 00:39:26.000
And then when DSW1 recovers, let's not forget we gave it a higher priority.

00:39:27.000 --> 00:39:32.000
Let's not forget we turned on preemption, and therefore it becomes active again.

00:39:32.000 --> 00:39:37.000
So, if we didn't have preemption turned on and we didn't have a higher priority, then

00:39:37.000 --> 00:39:39.000
DSW2 would remain active instead.

00:39:39.000 --> 00:39:44.000
So, based on our configuration, this is what happens when we fail back.

00:39:44.000 --> 00:39:54.000
But what we need to realize is that the default behavior of HSRP is purely based on those

00:39:54.000 --> 00:39:55.000
hello packets.

00:39:55.000 --> 00:39:59.000
Do I hear you or not, says the standby device.

00:39:59.000 --> 00:40:04.000
And if the standby device hears the active device, then the standby device remains active.

00:40:04.000 --> 00:40:07.000
If it doesn't hear the active device, then what's it going to do?

00:40:07.000 --> 00:40:09.000
It's going to promote itself to being active.

00:40:09.000 --> 00:40:13.000
But what if there's a failure over here somewhere?

00:40:13.000 --> 00:40:21.000
For example, what if gigabit 1 size 0 slash 13 fails or 1 size 0 slash 14 fails?

00:40:21.000 --> 00:40:39.000
Are the hello packets, folks, still going to be going back and forth here?

00:40:39.000 --> 00:40:40.000
Yeah.

00:40:40.000 --> 00:40:48.000
Which means that if both these interfaces go down, traffic's going to be sent here only

00:40:48.000 --> 00:40:52.000
to be dropped because that device cannot send it.

00:40:52.000 --> 00:40:53.000
Ah.

00:40:53.000 --> 00:40:59.000
So, we need in our production environments to make sure that we are not only concerned

00:40:59.000 --> 00:41:04.000
about a failure here somewhere, we're also concerned about failures upstream.

00:41:04.000 --> 00:41:07.000
For example, with our directly connected interfaces.

00:41:07.000 --> 00:41:13.000
So, the directly connected routed ports in our particular scenario, the routed ports

00:41:13.000 --> 00:41:22.000
of 13 and 14, we have the ability to turn on what is called HSRP interface tracking.

00:41:22.000 --> 00:41:27.000
And there's two different ways we can do this depending on the model of iOS you have and

00:41:27.000 --> 00:41:28.000
the device you have.

00:41:28.000 --> 00:41:35.000
So, for example, what we're using in our demo environment does it one way, but I have a

00:41:35.000 --> 00:41:39.000
bunch of switches here that do it a completely different way.

00:41:39.000 --> 00:41:44.000
And so, I'm going to teach you both ways today in case either or shows up on the exam.

00:41:44.000 --> 00:41:46.000
I want you to be prepared for it.

00:41:49.000 --> 00:41:58.000
So, the whole point here is that if, for example, an interface fails, I want to be able to tell

00:41:58.000 --> 00:42:01.000
this device that it should go active.

00:42:01.000 --> 00:42:04.000
That's what I'm trying to accomplish here.

00:42:04.000 --> 00:42:05.000
So, let me repeat that.

00:42:05.000 --> 00:42:12.000
If, let's say, an interface fails, I want to tell this device to go active.

00:42:12.000 --> 00:42:14.000
How can we do that?

00:42:14.000 --> 00:42:22.000
Well, the easiest way to do that is to lower our priority.

00:42:22.000 --> 00:42:36.000
If I lower my priority, if I lower my priority, then that forces DSW2 to go active.

00:42:36.000 --> 00:42:41.000
So, let me show you how you can do it right within HSRP.

00:42:41.000 --> 00:42:48.000
Now, my demo devices, like I said, don't support this method, but I have four switches right

00:42:48.000 --> 00:42:50.000
over there that do.

00:42:50.000 --> 00:42:54.000
And you could either see this option or the other option I'm going to show you momentarily

00:42:54.000 --> 00:42:57.000
on the certification exam.

00:42:57.000 --> 00:43:04.000
So, in this scenario here, I am in interface configuration mode, interface VLAN 10.

00:43:04.000 --> 00:43:12.000
Look what I type in standby, the group number, the word track, and then the interface I want

00:43:12.000 --> 00:43:16.000
to keep track of.

00:43:16.000 --> 00:43:18.000
So, what does this state?

00:43:18.000 --> 00:43:25.000
It states, if the interface is up-up, don't do anything.

00:43:25.000 --> 00:43:28.000
Let me repeat that.

00:43:28.000 --> 00:43:34.000
If the interface is up-up, don't do anything.

00:43:34.000 --> 00:43:47.000
If the interface is any other scenario other than up-up, like up-down, down-down, administratively

00:43:47.000 --> 00:43:48.000
down-down.

00:43:48.000 --> 00:44:01.000
If it's any of those options, lower my priority by, in this case, 250.

00:44:01.000 --> 00:44:07.000
So, if the interface is not up-up, lower my priority by 250.

00:44:07.000 --> 00:44:09.000
So, you can put any number you want there.

00:44:09.000 --> 00:44:10.000
That makes sense.

00:44:10.000 --> 00:44:13.000
So, let's just consider our scenario right now.

00:44:13.000 --> 00:44:19.000
What's the current priority, folks, of DSW-1?

00:44:19.000 --> 00:44:27.000
Current priority of DSW-1 is 110.

00:44:27.000 --> 00:44:31.000
What is the current priority of DSW-2?

00:44:31.000 --> 00:44:35.000
It is 100.

00:44:35.000 --> 00:44:43.000
So, let's say Gigabit Ethernet 1 slash 0 slash 13 fails.

00:44:43.000 --> 00:44:52.000
What is the minimum decrement value we need to get DSW-2 to take over?

00:44:52.000 --> 00:44:58.000
What is the minimum decrement value we need to get to in order for DSW-2 to take over?

00:44:58.000 --> 00:45:04.000
Well, if DSW-2 is 100, what do I have to lower this to?

00:45:04.000 --> 00:45:07.000
I would have to lower this to 99, right?

00:45:07.000 --> 00:45:08.000
Okay.

00:45:08.000 --> 00:45:11.000
So, as Conrad said, 11.

00:45:11.000 --> 00:45:14.000
What's 110 minus 11?

00:45:14.000 --> 00:45:16.000
99.

00:45:16.000 --> 00:45:21.000
So, we could literally just type in 11 here.

00:45:21.000 --> 00:45:30.000
And now, if Gigabit 13 fails, we minus 11 from 110.

00:45:30.000 --> 00:45:32.000
We get 99.

00:45:32.000 --> 00:45:36.000
So, my next hello packet that comes says 99.

00:45:36.000 --> 00:45:39.000
This device goes, oh, I better take over.

00:45:39.000 --> 00:45:40.000
Boom.

00:45:40.000 --> 00:45:41.000
It becomes active.

00:45:41.000 --> 00:45:46.000
And we're good to go.

00:45:46.000 --> 00:45:48.000
It's not bad.

00:45:48.000 --> 00:45:52.000
Now, let me teach you a little something else here.

00:45:52.000 --> 00:45:59.000
Do we really have to decrement, folks, fully?

00:45:59.000 --> 00:46:00.000
Let me rephrase this.

00:46:00.000 --> 00:46:01.000
Let me rephrase that.

00:46:01.000 --> 00:46:09.000
Do we really need DSW-2 to take over if only Gigabit 13 fails?

00:46:09.000 --> 00:46:15.000
What do you think?

00:46:15.000 --> 00:46:16.000
Not really, right?

00:46:16.000 --> 00:46:17.000
Because of what?

00:46:17.000 --> 00:46:20.000
Because of this interface here.

00:46:20.000 --> 00:46:26.000
We still have another path to go, right?

00:46:26.000 --> 00:46:29.000
So, we don't necessarily need that.

00:46:29.000 --> 00:46:32.000
So, this might not be the best option for you.

00:46:32.000 --> 00:46:34.000
What if we split it up?

00:46:34.000 --> 00:46:38.000
What if we said if one or the other fails?

00:46:38.000 --> 00:46:43.000
Okay, if one or the other fails, we'll just decrement a bit.

00:46:43.000 --> 00:46:44.000
Like, let's do this instead.

00:46:44.000 --> 00:46:46.000
Let's add another command.

00:46:46.000 --> 00:46:55.000
So, I'm going to type in standby 10 track Gigabit Ethernet 1 slash 0 slash 14.

00:46:55.000 --> 00:46:58.000
But in this case, let's do something like this.

00:46:58.000 --> 00:47:02.000
Let's do 7 and 7.

00:47:02.000 --> 00:47:04.000
Let's do 7 and 7.

00:47:04.000 --> 00:47:06.000
So, what does that mean?

00:47:06.000 --> 00:47:13.000
It means that if we have this scenario where Gig 1 slash 0 slash 13 fails, we subtract 7.

00:47:13.000 --> 00:47:16.000
What does that equal, 103?

00:47:16.000 --> 00:47:22.000
Are we still active in this scenario, yes or no?

00:47:22.000 --> 00:47:24.000
Yeah, of course we're still active, right?

00:47:24.000 --> 00:47:26.000
We still are higher than this.

00:47:26.000 --> 00:47:27.000
Okay.

00:47:27.000 --> 00:47:33.000
So, let's say we have this failure, minus 7 now, 103.

00:47:33.000 --> 00:47:36.000
Again, we're still active, right?

00:47:36.000 --> 00:47:46.000
So, imagine a scenario where you said, hey, you want to make sure that you only fail over to DSW2 if both of those links fail.

00:47:46.000 --> 00:47:47.000
Ha, ha, ha.

00:47:47.000 --> 00:47:49.000
Ha, ha, ha, ha, ha, ha.

00:47:49.000 --> 00:47:50.000
Right?

00:47:50.000 --> 00:47:52.000
Split it up somehow.

00:47:52.000 --> 00:47:58.000
Now, if both fail, now what's that number?

00:47:58.000 --> 00:48:02.000
110 minus 14.

00:48:02.000 --> 00:48:03.000
96, is it?

00:48:03.000 --> 00:48:05.000
I think my math can be pretty bad.

00:48:05.000 --> 00:48:10.000
But you get the picture, right?

00:48:10.000 --> 00:48:12.000
You get the picture now.

00:48:12.000 --> 00:48:17.000
Now, we have a failover as soon as both those interfaces fail.

00:48:17.000 --> 00:48:20.000
So, that's something to keep in mind for the exam.

00:48:20.000 --> 00:48:26.000
You can have multiple standby commands for multiple different purposes.

00:48:26.000 --> 00:48:28.000
Let's not forget, too, okay?

00:48:28.000 --> 00:48:30.000
Let's be clear about this, too.

00:48:30.000 --> 00:48:36.000
Remember how I said failure this way is based on hellos, right?

00:48:36.000 --> 00:48:39.000
Okay, well, what if this happens?

00:48:39.000 --> 00:48:47.000
What if this fails, this fails, this fails, this fails, but these four interfaces are still up and running?

00:48:47.000 --> 00:48:50.000
Are we still getting hellos back and forth?

00:48:50.000 --> 00:48:52.000
Are we still getting hellos?

00:48:52.000 --> 00:48:54.000
Yeah, of course we are.

00:48:54.000 --> 00:48:56.000
But this doesn't make sense now, right?

00:48:56.000 --> 00:48:58.000
Because traffic's going to end up doing this.

00:48:58.000 --> 00:49:00.000
I don't want that to happen.

00:49:00.000 --> 00:49:02.000
I don't want that to happen.

00:49:02.000 --> 00:49:09.000
So, maybe what we do is we also track these two interfaces as well.

00:49:09.000 --> 00:49:16.000
So, track gigabit ethernet 1 slash 0 slash 21 and gigabit ethernet 1 slash 0 slash 22.

00:49:16.000 --> 00:49:22.000
And if both of those interfaces fail, then I want to lower my priority.

00:49:22.000 --> 00:49:28.000
Because even though the hello packet's still going back and forth, right, now all of a sudden we've got suboptimal traffic forwarding.

00:49:28.000 --> 00:49:31.000
Because traffic might do something like this, or traffic might do something like that.

00:49:31.000 --> 00:49:33.000
We don't want that.

00:49:33.000 --> 00:49:38.000
So, always think, too, that just because it's based on hellos in here.

00:49:38.000 --> 00:49:44.000
Well, what if those two primary interfaces that are directly connected to ASW1 fail?

00:49:44.000 --> 00:49:47.000
Well, I don't want to be the default gateway then.

00:49:47.000 --> 00:49:50.000
Because that doesn't make sense from a traffic standpoint.

00:49:50.000 --> 00:49:53.000
So, I should track those ones as well and decrement them.

00:49:53.000 --> 00:49:55.000
So, it's not just about decrementing these interfaces.

00:49:55.000 --> 00:49:59.000
It's also about decrementing those in those oddball scenarios.

00:50:00.000 --> 00:50:02.000
Right.

00:50:02.000 --> 00:50:10.000
So, that is an example using the command that is right on the interface to accomplish your objective.

00:50:18.000 --> 00:50:19.000
Right.

00:50:19.000 --> 00:50:22.000
However, my switches right now don't do that.

00:50:22.000 --> 00:50:26.000
Yes, you can track port channels.

00:50:26.000 --> 00:50:27.000
You can track.

00:50:27.000 --> 00:50:28.000
Yes, absolutely.

00:50:28.000 --> 00:50:29.000
So, you can track port channels.

00:50:35.000 --> 00:50:48.000
So, this device, if I go to interface VLAN10 and we say standby 10 track, you'll see I can't put in the interface number at all.

00:50:48.000 --> 00:50:50.000
Can't put in the interface name.

00:50:50.000 --> 00:50:52.000
Can't put in the interface number at all.

00:50:53.000 --> 00:50:58.000
So, how do we do it on this type of platform then?

00:50:58.000 --> 00:51:03.000
So, in this case, you need to create what is called a tracking object.

00:51:03.000 --> 00:51:04.000
Okay.

00:51:04.000 --> 00:51:12.000
So, I'm going to show you how to create a tracking object instead.

00:51:12.000 --> 00:51:16.000
So, we're going to do the same scenario, but we're going to do a tracking object instead.

00:51:16.000 --> 00:51:18.000
So, let me back out of this config.

00:51:18.000 --> 00:51:19.000
Let me go here.

00:51:19.000 --> 00:51:21.000
And how do you create a tracking object?

00:51:21.000 --> 00:51:24.000
You type in track, and then you give it a number.

00:51:24.000 --> 00:51:27.000
So, let's just type in track 1 for today.

00:51:27.000 --> 00:51:29.000
Now, what do I want to track?

00:51:29.000 --> 00:51:34.000
I want to track the status of my interface.

00:51:38.000 --> 00:51:41.000
And what interface do I want to track?

00:51:41.000 --> 00:51:45.000
I want to track gigabit ethernet 1.0.0.13.

00:51:47.000 --> 00:51:49.000
And what do I want to track about it?

00:51:49.000 --> 00:51:57.000
I want to track its line protocol, meaning are you up or are you down?

00:51:57.000 --> 00:51:59.000
All right.

00:51:59.000 --> 00:52:06.000
Let's do the same thing now for we'll create another tracking object, a totally different one,

00:52:06.000 --> 00:52:10.000
but we'll create it for gigabit 1.0.0.14.

00:52:14.000 --> 00:52:17.000
Now, we'll go back to interface VLAN 10.

00:52:19.000 --> 00:52:24.000
And what we'll type in is standby 10 track 1.

00:52:24.000 --> 00:52:27.000
And now I put in my decrement value.

00:52:27.000 --> 00:52:30.000
What do I want to decrement it by?

00:52:30.000 --> 00:52:36.000
I want to decrement it by, we said, for example, 7.

00:52:38.000 --> 00:52:42.000
Let's do the same thing for tracking object number 2.

00:52:42.000 --> 00:52:46.000
So, tracking object 1 is keeping track of this.

00:52:46.000 --> 00:52:50.000
Tracking object 2 is keeping track of that.

00:52:50.000 --> 00:53:00.000
So, it's really the same thing, except I can't use the interfaces right in this command on this iOS version and platform.

00:53:00.000 --> 00:53:03.000
But I get the same result in the end.

00:53:03.000 --> 00:53:04.000
All right.

00:53:04.000 --> 00:53:12.000
So, now I want to type in show track.

00:53:12.000 --> 00:53:18.000
And you're going to see we have two different tracking objects.

00:53:18.000 --> 00:53:24.000
We have a tracking object 1 for gigabit 1.0.0.13 and a tracking object 2 for gigabit 1.

00:53:24.000 --> 00:53:25.000
And it says it's up.

00:53:25.000 --> 00:53:26.000
Why?

00:53:26.000 --> 00:53:27.000
Because the interface is up.

00:53:27.000 --> 00:53:34.000
And you'll see that we have attached it to HSRP interface VLAN 10 group 10.

00:53:35.000 --> 00:53:42.000
Now, if I type in show standby, we're going to see for interface VLAN 10, our priority is 1.10.

00:53:42.000 --> 00:53:47.000
It is configured in our running config as 1.10.

00:53:47.000 --> 00:53:51.000
And right now, it is 1.10.

00:53:51.000 --> 00:53:57.000
And we are going to use these tracking objects to keep track of everything.

00:53:57.000 --> 00:54:02.000
So, let's go ahead and bring down one of our interfaces and see how this changes.

00:54:02.000 --> 00:54:06.000
So, we'll type in configure terminal interface gigabit ethernet 1.0.0.13.

00:54:06.000 --> 00:54:09.000
Let's shut that down.

00:54:09.000 --> 00:54:12.000
And you'll see here that the tracking object goes down.

00:54:12.000 --> 00:54:16.000
So, since the tracking object has gone down, what does that mean?

00:54:16.000 --> 00:54:21.000
Well, let's type in do show track first to show you that, yes, it has gone down.

00:54:21.000 --> 00:54:22.000
Why?

00:54:22.000 --> 00:54:25.000
Because I shut it down.

00:54:25.000 --> 00:54:32.000
And now, if we look at the output of do show standby, what are we going to see?

00:54:32.000 --> 00:54:38.000
We're going to see that our priority is now 1.03.

00:54:38.000 --> 00:54:42.000
So, it is configured as 1.10, but now it's 1.03.

00:54:42.000 --> 00:54:45.000
So, you're seeing why the number shows up twice.

00:54:45.000 --> 00:54:48.000
The number shows up twice to show you what you've configured it as,

00:54:48.000 --> 00:55:03.000
and then the other number is what it actually is.

00:55:03.000 --> 00:55:04.000
Okay.

00:55:04.000 --> 00:55:05.000
So, that's what.

00:55:05.000 --> 00:55:19.000
Now, let's go ahead and bring down 14.

00:55:19.000 --> 00:55:21.000
So, go do show standby now.

00:55:21.000 --> 00:55:28.000
And you'll see here that we are now priority of 96,

00:55:28.000 --> 00:55:32.000
which means DSW2 should now have promoted itself to active.

00:55:32.000 --> 00:55:34.000
Look, I'm in speak state right now.

00:55:34.000 --> 00:55:36.000
So, I've demoted myself.

00:55:36.000 --> 00:55:46.000
DSW2 is now active, and DSW1 should promote itself here very shortly to standby.

00:55:46.000 --> 00:55:47.000
And there you go.

00:55:47.000 --> 00:55:48.000
It has.

00:55:48.000 --> 00:55:49.000
Right?

00:55:49.000 --> 00:55:50.000
Question coming in.

00:55:50.000 --> 00:55:54.000
If track is the same thing as doing it on the interface, then which would be best to use?

00:55:54.000 --> 00:55:55.000
Oh, okay.

00:55:55.000 --> 00:55:57.000
So, you must have missed what I had said about that.

00:55:57.000 --> 00:55:58.000
All right.

00:55:58.000 --> 00:56:07.000
So, as I was explaining a while ago, if your device supports the interface option, right,

00:56:07.000 --> 00:56:10.000
then you can go ahead and use that.

00:56:10.000 --> 00:56:14.000
Use the interface option that I gave the whole explanation of right here.

00:56:14.000 --> 00:56:15.000
Okay?

00:56:15.000 --> 00:56:16.000
Fine.

00:56:16.000 --> 00:56:18.000
If that is available, do it that way.

00:56:18.000 --> 00:56:19.000
Okay?

00:56:19.000 --> 00:56:24.000
If it's not available on your platform, then you have to do it this way.

00:56:24.000 --> 00:56:27.000
So, it could show up either or on the certification exam.

00:56:27.000 --> 00:56:28.000
Right?

00:56:28.000 --> 00:56:31.000
And that's why I'm showing both methods, just in case.

00:56:31.000 --> 00:56:36.000
For the longest time, I always did it this way, always did it this way, always did it this way.

00:56:36.000 --> 00:56:39.000
And then all of a sudden, I had a platform with an operator.

00:56:39.000 --> 00:56:40.000
I'm like, what?

00:56:40.000 --> 00:56:42.000
Why is that not available?

00:56:42.000 --> 00:56:45.000
And I had to start doing it this way on those devices.

00:56:45.000 --> 00:56:46.000
All right.

00:56:46.000 --> 00:56:47.000
So, just that way, there you know.

00:56:47.000 --> 00:56:49.000
There's the two options.

00:56:49.000 --> 00:56:50.000
All right.

00:56:50.000 --> 00:56:54.000
And this option doesn't even exist for VRRP, by the way.

00:56:54.000 --> 00:56:57.000
You can only do it this way with VRRP.

00:56:57.000 --> 00:56:59.000
You cannot do it this way.

00:57:02.000 --> 00:57:03.000
All right.

00:57:03.000 --> 00:57:04.000
So, there you go.

00:57:04.000 --> 00:57:08.000
That is this cool little feature in action.

00:57:08.000 --> 00:57:15.000
So, interface, range, gigabit ethernet, one slash zero slash 13 and 14.

00:57:15.000 --> 00:57:17.000
No.

00:57:17.000 --> 00:57:18.000
All right.

00:57:18.000 --> 00:57:20.000
That's three to 14, but that's okay.

00:57:22.000 --> 00:57:23.000
All right.

00:57:23.000 --> 00:57:24.000
We're back up.

00:57:24.000 --> 00:57:25.000
We're good to go.

00:57:25.000 --> 00:57:26.000
All right.

00:57:26.000 --> 00:57:28.000
And therefore, I should promote myself to active, and I did right there.

00:57:28.000 --> 00:57:29.000
You can see.

00:57:29.000 --> 00:57:30.000
Why?

00:57:30.000 --> 00:57:32.000
Because I have the higher priority.

00:57:32.000 --> 00:57:33.000
All right.

00:57:33.000 --> 00:57:34.000
But there's more.

00:57:34.000 --> 00:57:35.000
There's more.

00:57:35.000 --> 00:57:39.000
I sound like one of those late night infomercials.

00:57:39.000 --> 00:57:40.000
But wait.

00:57:40.000 --> 00:57:41.000
There's more.

00:57:41.000 --> 00:57:46.000
Because we have to consider some other types of scenarios.

00:57:46.000 --> 00:57:50.000
And when I say other types of scenarios, I'm talking about scenarios where the failure

00:57:50.000 --> 00:57:54.000
could be further in our environment somewhere.

00:57:54.000 --> 00:57:58.000
It could be way further in our environment.

00:57:58.000 --> 00:58:05.000
And so, for example, if under normal conditions, we always go this way, but all of a sudden,

00:58:05.000 --> 00:58:14.000
this interface went down, and we wanted to make sure that if this went down, we went

00:58:14.000 --> 00:58:16.000
this way instead.

00:58:16.000 --> 00:58:19.000
How could we do that?

00:58:20.000 --> 00:58:24.000
Well, that's where you need to use something like IPSLA.

00:58:24.000 --> 00:58:33.000
How many of you have used IPSLA before on a Cisco device?

00:58:38.000 --> 00:58:39.000
Yeah.

00:58:39.000 --> 00:58:40.000
Right.

00:58:40.000 --> 00:58:43.000
There's many different things you can do with IPSLA.

00:58:43.000 --> 00:58:46.000
Many different things you can do with IPSLA.

00:58:46.000 --> 00:58:47.000
Right.

00:58:47.000 --> 00:58:50.000
So, for example, you can use IPSLA to send a simple ping.

00:58:50.000 --> 00:58:52.000
A simple ping to test connectivity.

00:58:52.000 --> 00:58:54.000
Are you there, or are you not there?

00:58:54.000 --> 00:58:55.000
If you're there, awesome.

00:58:55.000 --> 00:58:57.000
If you're not there, blah.

00:58:57.000 --> 00:58:59.000
And then we can have something occur.

00:58:59.000 --> 00:59:00.000
Right.

00:59:04.000 --> 00:59:16.000
When it comes to IPSLA, it's going to be covered for you in the additional videos.

00:59:16.000 --> 00:59:21.000
So, for example, under management protocols and services for Encore version 1.1, so after

00:59:21.000 --> 00:59:26.000
day eight, you still have other videos to remember to watch, I have an IPSLA configuration

00:59:26.000 --> 00:59:32.000
and verification video right there that you can utilize.

00:59:32.000 --> 00:59:34.000
And that will teach you some aspects of IPSLA.

00:59:34.000 --> 00:59:36.000
It's a massive feature.

00:59:36.000 --> 00:59:39.000
It's a massive tool that is available on Cisco devices.

00:59:39.000 --> 00:59:43.000
For example, like I said, you can send a ping, and then based on the ping being successful

00:59:44.000 --> 00:59:47.000
or not, have your router do something on that.

00:59:47.000 --> 00:59:50.000
You can even test, for example, round-trip times.

00:59:50.000 --> 00:59:54.000
So, let's say you have a WAN connection, and you want to keep an eye on the WAN connection

00:59:54.000 --> 00:59:56.000
over your service provider.

00:59:56.000 --> 00:59:58.000
What is the one-way delay?

00:59:58.000 --> 00:59:59.000
What is one-way jitter?

00:59:59.000 --> 01:00:03.000
What is one-way values?

01:00:03.000 --> 01:00:04.000
Why?

01:00:04.000 --> 01:00:06.000
Because maybe you want to make sure you're getting what you're paying for.

01:00:06.000 --> 01:00:10.000
And then also, what are the return values between that device?

01:00:10.000 --> 01:00:12.000
So, that's what IPSLA can do for you.

01:00:14.000 --> 01:00:19.000
So, for example, I'll give you a quick demo here, because demos are always fun.

01:00:21.000 --> 01:00:26.000
Let's go ahead on DSW1 and generate a probe.

01:00:29.000 --> 01:00:32.000
So, let me get the IP address, show IP interface brief.

01:00:33.000 --> 01:00:38.000
So, it's that IP address right there we are going to ping.

01:00:39.000 --> 01:00:41.000
So, that was R1's outside interface.

01:00:41.000 --> 01:00:47.000
So, I'll create something like this, IPSLA, and then I give it a number.

01:00:47.000 --> 01:00:49.000
So, I can reference that number.

01:00:49.000 --> 01:00:51.000
So, this is probe number one.

01:00:51.000 --> 01:00:54.000
And you'll see here, there are many different types of probes I can create.

01:00:54.000 --> 01:00:57.000
Depending on the platform, you'll have more probes or less probes.

01:00:57.000 --> 01:00:59.000
But this is the IP address.

01:00:59.000 --> 01:01:01.000
You'll have more probes or less probes.

01:01:01.000 --> 01:01:04.000
But this is the ICMP echo probe, meaning ping.

01:01:04.000 --> 01:01:06.000
So, I'm going to do an ICMP echo.

01:01:06.000 --> 01:01:08.000
What's the destination?

01:01:08.000 --> 01:01:11.000
We said the destination was going to be this particular IP address right there.

01:01:11.000 --> 01:01:13.000
So, I'll plug that in.

01:01:14.000 --> 01:01:17.000
And then from what source?

01:01:17.000 --> 01:01:18.000
So, what source?

01:01:18.000 --> 01:01:23.000
We'll do source interface gigabit ethernet 1.0.0.13.

01:01:23.000 --> 01:01:27.000
So, pinging out there, pinging out there to that IP address on the other side.

01:01:29.000 --> 01:01:32.000
And we're going to do that, let's say, every five seconds.

01:01:32.000 --> 01:01:34.000
Every five seconds.

01:01:34.000 --> 01:01:37.000
Now what we're going to do is we're going to set up a schedule.

01:01:37.000 --> 01:01:39.000
So, IPSLA schedule.

01:01:39.000 --> 01:01:42.000
And there's many different ways that you can schedule your IPSLA instances.

01:01:42.000 --> 01:01:44.000
So, I talk about that in the IPSLA discussion.

01:01:44.000 --> 01:01:48.000
But I'm going to schedule it for IPSLA 1, which is the one we just created.

01:01:48.000 --> 01:01:49.000
Right?

01:01:49.000 --> 01:01:50.000
We just created IPSLA 1.

01:01:50.000 --> 01:01:52.000
So, that's what I'm going to schedule now.

01:01:52.000 --> 01:01:55.000
And I can schedule it to age out.

01:01:55.000 --> 01:01:56.000
I can set a life for it.

01:01:56.000 --> 01:01:57.000
I can make it recurring.

01:01:57.000 --> 01:01:58.000
I can start it, for example.

01:01:58.000 --> 01:02:00.000
At a certain time of the day.

01:02:00.000 --> 01:02:01.000
Well, I want to start it now.

01:02:01.000 --> 01:02:05.000
As soon as I hit enter, I want it to start now in this particular example.

01:02:05.000 --> 01:02:07.000
And how long do I want it to last for?

01:02:07.000 --> 01:02:08.000
What's its lifetime?

01:02:08.000 --> 01:02:11.000
Well, in this case, I'm going to allow it to last forever.

01:02:11.000 --> 01:02:16.000
So, I just want this ping to start now and happen every five seconds until I

01:02:16.000 --> 01:02:19.000
manually shut it off.

01:02:19.000 --> 01:02:26.000
So, now if I type in do show IPSLA statistics,

01:02:27.000 --> 01:02:30.000
you're going to see here that I have three pings so far.

01:02:30.000 --> 01:02:32.000
That returned an okay.

01:02:32.000 --> 01:02:34.000
It means when I ping there, I got a response back.

01:02:34.000 --> 01:02:36.000
I ping there, I got a response back.

01:02:36.000 --> 01:02:38.000
I ping there, I got a response back.

01:02:38.000 --> 01:02:42.000
And you'll see it's now up to six.

01:02:42.000 --> 01:02:52.000
So, let's just go ahead and shut down that interface.

01:02:52.000 --> 01:02:57.000
And what we should see here is that eventually we start getting an error

01:02:57.000 --> 01:02:58.000
message.

01:02:58.000 --> 01:03:00.000
And there you go.

01:03:00.000 --> 01:03:01.000
Time out.

01:03:01.000 --> 01:03:02.000
And now it's one.

01:03:02.000 --> 01:03:03.000
Okay?

01:03:03.000 --> 01:03:04.000
So, this is just the probe.

01:03:04.000 --> 01:03:06.000
The probe is doing the probe.

01:03:06.000 --> 01:03:07.000
That's it.

01:03:07.000 --> 01:03:08.000
Nothing else.

01:03:08.000 --> 01:03:09.000
Okay, that's all it is.

01:03:09.000 --> 01:03:10.000
In this case, it's a probe.

01:03:10.000 --> 01:03:14.000
That's what SLA is for, to set up probes, to set up artificial traffic,

01:03:14.000 --> 01:03:20.000
to set up, like if I wanted to check to see what the numerical statistics are

01:03:20.000 --> 01:03:22.000
from here to there for voiceover IP.

01:03:22.000 --> 01:03:26.000
I could create a fake voiceover IP packet, same size, same shape,

01:03:26.000 --> 01:03:28.000
same QOS markings.

01:03:28.000 --> 01:03:31.000
And then I can measure the information, delay, round trip, jitter.

01:03:31.000 --> 01:03:32.000
That's what you can do with this.

01:03:32.000 --> 01:03:33.000
Tons of stuff you can do.

01:03:33.000 --> 01:03:35.000
Tons of stuff you can do.

01:03:35.000 --> 01:03:38.000
All right, so now I'm just going to bring up the interface so that way

01:03:38.000 --> 01:03:40.000
there we start having successes again.

01:03:40.000 --> 01:03:41.000
All right?

01:03:41.000 --> 01:03:44.000
So, we should see here everything should be coming back to normal real

01:03:44.000 --> 01:03:45.000
soon.

01:03:45.000 --> 01:03:48.000
Uh-oh.

01:03:48.000 --> 01:03:56.000
Uh-oh.

01:03:56.000 --> 01:03:58.000
Why is the ping not working?

01:03:58.000 --> 01:04:04.000
It should be working.

01:04:04.000 --> 01:04:14.000
Why is the interface not running?

01:04:14.000 --> 01:04:16.000
Nothing better than live demos.

01:04:16.000 --> 01:04:22.000
Okay, so it's up, up.

01:04:22.000 --> 01:04:23.000
There you go.

01:04:23.000 --> 01:04:24.000
I'm just impatient.

01:04:24.000 --> 01:04:25.000
That's my problem.

01:04:25.000 --> 01:04:26.000
All right.

01:04:26.000 --> 01:04:27.000
So, we're good.

01:04:27.000 --> 01:04:31.000
So, now what we have to think about is this is going to be for HSRP example.

01:04:31.000 --> 01:04:34.000
So, what do I need now?

01:04:34.000 --> 01:04:38.000
I need a tracking object.

01:04:38.000 --> 01:04:40.000
So, let's create a tracking object.

01:04:40.000 --> 01:04:42.000
Call it track three.

01:04:42.000 --> 01:04:45.000
And we're going to track IP.

01:04:45.000 --> 01:04:48.000
We're going to track SLA.

01:04:48.000 --> 01:04:52.000
We are going to track entry number one that we created.

01:04:52.000 --> 01:04:54.000
And what are we just wanting to track?

01:04:54.000 --> 01:04:55.000
The state of it.

01:04:55.000 --> 01:04:56.000
That's it.

01:04:56.000 --> 01:04:57.000
Just the state of it.

01:04:57.000 --> 01:04:58.000
Nothing else.

01:04:58.000 --> 01:04:59.000
What does that mean?

01:04:59.000 --> 01:05:05.000
It means if your state is okay, my tracking object is up.

01:05:05.000 --> 01:05:10.000
If your state is time out, then my tracking object goes down.

01:05:10.000 --> 01:05:12.000
So, let's type in do show track.

01:05:12.000 --> 01:05:13.000
And what do we have now?

01:05:13.000 --> 01:05:18.000
We can now see that we are tracking the SLA instance.

01:05:18.000 --> 01:05:21.000
So, if it's okay, go back up here.

01:05:21.000 --> 01:05:25.000
If it's okay, then my tracking object is up.

01:05:25.000 --> 01:05:30.000
If it's not okay, meaning it's time out, then my tracking object goes down.

01:05:30.000 --> 01:05:32.000
So, let me test that for you.

01:05:32.000 --> 01:05:34.000
We'll shut down that interface.

01:05:34.000 --> 01:05:35.000
Right?

01:05:35.000 --> 01:05:36.000
And it just doesn't have to be the interface.

01:05:36.000 --> 01:05:39.000
It's can I no longer ping that IP address?

01:05:39.000 --> 01:05:41.000
Because if I can no longer ping that IP address,

01:05:41.000 --> 01:05:43.000
then my tracking object goes down for whatever reason.

01:05:43.000 --> 01:05:44.000
Right?

01:05:44.000 --> 01:05:46.000
So, now the tracking object is down, as you can see.

01:05:46.000 --> 01:05:48.000
So, we look at the tracking object.

01:05:48.000 --> 01:05:49.000
It now says it's down.

01:05:49.000 --> 01:05:50.000
All right.

01:05:50.000 --> 01:05:51.000
Cool.

01:05:51.000 --> 01:05:55.000
Let's bring that back up.

01:05:55.000 --> 01:06:00.000
And while that's coming up, let's now show you how to apply this to HSRP.

01:06:00.000 --> 01:06:04.000
So, for HSRP, what we're going to do is we are going to now type in

01:06:05.000 --> 01:06:15.000
interface VLAN 10, and we'll type in standby for group 10, track,

01:06:15.000 --> 01:06:16.000
and what object is that?

01:06:16.000 --> 01:06:19.000
Tracking object number three.

01:06:19.000 --> 01:06:20.000
And what are we going to do?

01:06:20.000 --> 01:06:22.000
We're going to decrement our priority.

01:06:22.000 --> 01:06:28.000
Let's say, in this case, let's decrement it by 110 for fun.

01:06:28.000 --> 01:06:31.000
Now, let's just make sure we're back up here.

01:06:31.000 --> 01:06:33.000
That looks good.

01:06:33.000 --> 01:06:36.000
Now, if the tracking object is not back up yet, which it's not back up,

01:06:36.000 --> 01:06:37.000
you're going to see we're going to fail over.

01:06:37.000 --> 01:06:38.000
Yeah.

01:06:38.000 --> 01:06:39.000
You see how we failed over?

01:06:39.000 --> 01:06:44.000
Because the tracking object hasn't come back up yet.

01:06:44.000 --> 01:06:45.000
But we're failing over.

01:06:45.000 --> 01:06:48.000
DSW2 is now active because the tracking object is down.

01:06:48.000 --> 01:06:53.000
But, look, the tracking object went back up, and now we're active again.

01:06:53.000 --> 01:06:54.000
Right?

01:06:54.000 --> 01:06:56.000
So, we've attached it.

01:06:56.000 --> 01:07:00.000
Do show standby.

01:07:00.000 --> 01:07:03.000
And if you go down, you'll see that we have three tracking objects now.

01:07:03.000 --> 01:07:06.000
So, this one is tracking object number three.

01:07:06.000 --> 01:07:10.000
Tracking object number three is tracking what?

01:07:10.000 --> 01:07:14.000
The status of IPSLA, whether it's the ping's good or the ping's not good.

01:07:14.000 --> 01:07:15.000
So, the ping's good.

01:07:15.000 --> 01:07:16.000
Tracking object's up.

01:07:16.000 --> 01:07:18.000
My priority's 110.

01:07:18.000 --> 01:07:19.000
Ping's bad.

01:07:19.000 --> 01:07:20.000
Tracking object's down.

01:07:20.000 --> 01:07:24.000
Therefore, my priority gets decremented by 110.

01:07:24.000 --> 01:07:28.000
So, let's go ahead and bring down that IP address now.

01:07:28.000 --> 01:07:30.000
And we'll see that the ping's going to fail.

01:07:30.000 --> 01:07:35.000
When the ping fails, what's going to happen?

01:07:35.000 --> 01:07:36.000
Ping fails.

01:07:36.000 --> 01:07:37.000
Tracking object goes down.

01:07:37.000 --> 01:07:43.000
DSW2 goes active.

01:07:43.000 --> 01:07:44.000
Bam.

01:07:44.000 --> 01:07:46.000
And notice I've done all of this on DSW1.

01:07:46.000 --> 01:07:49.000
But because I'm decrementing my priority,

01:07:49.000 --> 01:07:52.000
DSW2 through the hello package is going to know what to do.

01:07:52.000 --> 01:07:55.000
So, if you look here, my priority's actually zero.

01:07:55.000 --> 01:07:56.000
Why?

01:07:56.000 --> 01:07:58.000
Because the tracking object's down.

01:07:58.000 --> 01:08:00.000
So, this is something you have to be able to read yourself, too,

01:08:00.000 --> 01:08:02.000
on the potential exam folks.

01:08:02.000 --> 01:08:03.000
Right?

01:08:03.000 --> 01:08:04.000
For example, if you look in here and it says,

01:08:04.000 --> 01:08:06.000
Priority zero, configured 10.

01:08:06.000 --> 01:08:08.000
Priority zero, configured 110.

01:08:08.000 --> 01:08:10.000
And they ask you, why is your priority zero right now?

01:08:10.000 --> 01:08:15.000
Well, the priority's zero because tracking object three is down.

01:08:15.000 --> 01:08:18.000
But that might not be one of the options, right?

01:08:18.000 --> 01:08:22.000
It might be based on the fact that, yes, tracking object three is down,

01:08:22.000 --> 01:08:25.000
but then you need to show track.

01:08:25.000 --> 01:08:28.000
Show track says, okay, we're monitoring IPSLA.

01:08:28.000 --> 01:08:34.000
And so, we type in do show IPSLA statistics.

01:08:34.000 --> 01:08:35.000
And what do we see?

01:08:35.000 --> 01:08:36.000
Timeout.

01:08:36.000 --> 01:08:37.000
And then you look at the answer options.

01:08:37.000 --> 01:08:42.000
The answer options say IPSLA process ID one,

01:08:42.000 --> 01:08:47.000
or IPSLA instance one is timeout.

01:08:47.000 --> 01:08:50.000
You see how all of these are coming together at the CCNP level?

01:08:50.000 --> 01:08:53.000
Different features, different functions, different things like that.

01:08:53.000 --> 01:08:54.000
Right?

01:08:54.000 --> 01:08:56.000
So, you'll learn a little bit more about IPSLA later on.

01:08:56.000 --> 01:09:04.000
And I'll show you some other options in IPSLA like, oh, my gosh,

01:09:04.000 --> 01:09:05.000
why am I drawing a blank?

01:09:05.000 --> 01:09:06.000
Oh, floating static routes.

01:09:06.000 --> 01:09:09.000
Floating static routes will be covered in that one as well.

01:09:09.000 --> 01:09:12.000
I'll also talk about UDP jitter in that one.

01:09:12.000 --> 01:09:14.000
So, two important ones for the certification exam.

01:09:14.000 --> 01:09:18.000
So, keep an eye out for that when you do that review at that point in time.

01:09:18.000 --> 01:09:20.000
And remember what we talked about here when it comes to these things.

01:09:21.000 --> 01:09:22.000
All right.

01:09:22.000 --> 01:09:23.000
So, a lot of different things, as you can see here,

01:09:23.000 --> 01:09:26.000
when it comes to HSRP to get it to work the way you want it to work,

01:09:26.000 --> 01:09:29.000
so that way there you can accomplish your particular objectives that you

01:09:29.000 --> 01:09:30.000
need to.

01:09:30.000 --> 01:09:34.000
All right.

01:09:34.000 --> 01:09:35.000
Let's talk about timers now.

01:09:35.000 --> 01:09:40.000
So, as we said, with timers, our default timers were 3 and 10.

01:09:40.000 --> 01:09:45.000
So, you can easily change your timers to things like 1 is the lowest

01:09:45.000 --> 01:09:49.000
and 3 is the lowest if you use that particular command.

01:09:49.000 --> 01:09:52.000
So, if you use the command standby, the group number, timers,

01:09:52.000 --> 01:09:58.000
the lowest you can do is 1 and then 3 for the actual hold-down timer,

01:09:58.000 --> 01:10:02.000
because they recommend 3 times the hello for your hold-down timer.

01:10:02.000 --> 01:10:06.000
But there is another command you can use, and that is timers msec,

01:10:06.000 --> 01:10:08.000
milliseconds.

01:10:08.000 --> 01:10:12.000
So, instead of typing in the time that you want, 1 second and 3 seconds,

01:10:12.000 --> 01:10:17.000
type in msec first, and then you can get millisecond,

01:10:17.000 --> 01:10:20.000
submillisecond timers, right, subsecond timers.

01:10:20.000 --> 01:10:25.000
And so, 500 milliseconds and 2750 milliseconds.

01:10:25.000 --> 01:10:27.000
Now, what's the lowest you can actually do?

01:10:27.000 --> 01:10:32.000
Standby, 10, timers.

01:10:32.000 --> 01:10:35.000
So, just to show you here, you'll see it says 1 to 254 for the hello,

01:10:35.000 --> 01:10:39.000
and then they're saying 2 to 255, but they recommend 1 and 3 if that's the

01:10:39.000 --> 01:10:40.000
lowest you go.

01:10:40.000 --> 01:10:44.000
But if you type in msec, as you can see, lowest is 15 milliseconds.

01:10:44.000 --> 01:10:45.000
Okay.

01:10:45.000 --> 01:10:47.000
That is probably not going to work for most of you,

01:10:47.000 --> 01:10:50.000
because you also have to remember that that is how often a hello packet is

01:10:50.000 --> 01:10:52.000
going to be sent.

01:10:52.000 --> 01:10:58.000
So, if I do 15 as an example, and then we do our msec, and we say 50,

01:10:58.000 --> 01:11:00.000
50 milliseconds,

01:11:00.000 --> 01:11:05.000
that means that your devices are going to have to receive a hello packet

01:11:05.000 --> 01:11:08.000
once every 50 milliseconds.

01:11:08.000 --> 01:11:11.000
And if there's any congestion at all in that layer 2 network where the

01:11:12.000 --> 01:11:18.000
hello packet's traversing, if it's delayed by 1 millisecond,

01:11:18.000 --> 01:11:21.000
and it goes over 50 milliseconds by 1 millisecond,

01:11:21.000 --> 01:11:23.000
you're going to have a failover.

01:11:23.000 --> 01:11:26.000
And the last thing you want is for your routers to be failing over,

01:11:26.000 --> 01:11:28.000
failing back, failing over, failing back, failing over,

01:11:28.000 --> 01:11:30.000
failing back, failing over, failing back.

01:11:30.000 --> 01:11:31.000
So, be careful with that in the real world.

01:11:31.000 --> 01:11:37.000
Just because you can do it doesn't mean you want to do it.

01:11:37.000 --> 01:11:39.000
And even on these devices here, DSW1 and DSW2,

01:11:39.000 --> 01:11:43.000
I've done this before as a demo, and I failed over, failed back, failed.

01:11:43.000 --> 01:11:47.000
And there's no traffic in this environment.

01:11:47.000 --> 01:11:48.000
There's minuscule traffic.

01:11:48.000 --> 01:11:52.000
But by the time you transmit it, it gets to the other side.

01:11:52.000 --> 01:11:54.000
The other side has to process it.

01:11:54.000 --> 01:11:57.000
I mean, it could easily be 50 milliseconds.

01:11:57.000 --> 01:11:59.000
So, but those are options you have.

01:11:59.000 --> 01:12:00.000
Just keep in mind.

01:12:00.000 --> 01:12:02.000
So, fine-tuning them, tweaking them,

01:12:02.000 --> 01:12:06.000
so that way there you have minimal packet loss is absolutely a recommended

01:12:06.000 --> 01:12:07.000
best practice.

01:12:07.000 --> 01:12:14.000
But you now have to think about the fact that you also need to consider your

01:12:14.000 --> 01:12:16.000
preemption.

01:12:16.000 --> 01:12:22.000
So, we've seen today in all of my examples how preemption occurs pretty

01:12:22.000 --> 01:12:28.000
quickly, meaning that if all of a sudden the active routers interfaces come

01:12:28.000 --> 01:12:29.000
back up, what happens?

01:12:29.000 --> 01:12:32.000
It automatically promotes itself.

01:12:32.000 --> 01:12:36.000
So, do you remember the example I gave earlier where PC1,

01:12:36.000 --> 01:12:39.000
we were looking at its continuous ping.

01:12:39.000 --> 01:12:42.000
We failed over to DSW2, we lost a packet.

01:12:42.000 --> 01:12:46.000
We failed back over to DSW1, and we lost a packet.

01:12:46.000 --> 01:12:52.000
Okay, I don't want to lose any packets when the active router or the router

01:12:52.000 --> 01:12:53.000
becomes active.

01:12:53.000 --> 01:12:58.000
So, if we had a failover, and now I'm going back to being active DSW1,

01:12:58.000 --> 01:13:00.000
I don't want to lose any packets.

01:13:00.000 --> 01:13:03.000
In our case, why did we lose packets?

01:13:04.000 --> 01:13:07.000
Well, it could have been because of spanning tree protocol not fully

01:13:07.000 --> 01:13:08.000
converging yet.

01:13:08.000 --> 01:13:15.000
It could have been because of OSPF not fully converging yet.

01:13:15.000 --> 01:13:18.000
Remember, I brought down my interfaces.

01:13:18.000 --> 01:13:24.000
So, if I brought down my interfaces and bring them back up, right,

01:13:24.000 --> 01:13:29.000
is it possible that if I brought down interface VLAN10,

01:13:29.000 --> 01:13:32.000
that OSPF would then have to relearn about that, reshare that?

01:13:32.000 --> 01:13:33.000
Yeah, absolutely.

01:13:33.000 --> 01:13:37.000
So, the fact is that you don't want to preempt too fast.

01:13:37.000 --> 01:13:41.000
So, standby is active right now.

01:13:41.000 --> 01:13:48.000
This is nonexistent, meaning when this comes back up, how fast do I take over?

01:13:48.000 --> 01:13:50.000
How fast do I become active again?

01:13:50.000 --> 01:13:52.000
That's what you want to delay here.

01:13:52.000 --> 01:13:55.000
You want to delay that based on what?

01:13:55.000 --> 01:13:58.000
Based on everything else that's going on in your environment.

01:13:58.000 --> 01:13:59.000
So, you've got to measure that.

01:13:59.000 --> 01:14:01.000
You've got to measure that.

01:14:01.000 --> 01:14:03.000
So, how do you measure that?

01:14:03.000 --> 01:14:06.000
It means you are going to have to figure out how long from the time that these

01:14:06.000 --> 01:14:10.000
interfaces come up or these interfaces come up or interface VLAN10 comes up,

01:14:10.000 --> 01:14:15.000
how long does it take before the network is stable?

01:14:15.000 --> 01:14:19.000
Once you figure that number out, add a few seconds to it,

01:14:19.000 --> 01:14:21.000
and that's going to be your delay time.

01:14:21.000 --> 01:14:23.000
So, you might want to delay five seconds.

01:14:23.000 --> 01:14:25.000
You might want to delay ten seconds.

01:14:25.000 --> 01:14:27.000
You might even have to delay a whole minute,

01:14:27.000 --> 01:14:31.000
depending on the scenario and situations that you have in your environment.

01:14:31.000 --> 01:14:34.000
The last thing you want to do is take over as active,

01:14:34.000 --> 01:14:38.000
but the rest of the network is not ready for you.

01:14:38.000 --> 01:14:41.000
And if that's the case, then you're just going to drop traffic.

01:14:41.000 --> 01:14:43.000
We don't want that to happen.

01:14:43.000 --> 01:14:45.000
That's what preemption delay allows you to eliminate.

01:14:45.000 --> 01:14:51.000
So, if you do preemption delay minimum, that is for the scenario I just gave you.

01:14:51.000 --> 01:14:56.000
Okay, but preemption delay reload is whenever you reload the device.

01:14:56.000 --> 01:14:59.000
So, for example, let's say we reloaded this device right now.

01:14:59.000 --> 01:15:00.000
Reload, what happens?

01:15:00.000 --> 01:15:03.000
I'm no longer active, you're active.

01:15:03.000 --> 01:15:09.000
So, when this device finally reloads, its interfaces are going to be up and running,

01:15:09.000 --> 01:15:13.000
it's going to start sending hello packets, and all of a sudden it's going to go active.

01:15:13.000 --> 01:15:18.000
Well, what if the rest of this has not converged yet for OSPF?

01:15:18.000 --> 01:15:23.000
What if there's other features and services that are still turning on?

01:15:24.000 --> 01:15:26.000
Then all of a sudden you're active and you're dropping all the traffic

01:15:26.000 --> 01:15:28.000
because you don't know where to go with it.

01:15:28.000 --> 01:15:31.000
You don't have an updated routing table yet, you don't have this, you don't have that,

01:15:31.000 --> 01:15:32.000
this is not working, that's not working.

01:15:32.000 --> 01:15:39.000
So, you have to figure out how long does it take my device to fully boot, fully load,

01:15:39.000 --> 01:15:43.000
learn everything it needs to learn, converge everything it needs to converge,

01:15:43.000 --> 01:15:45.000
and then in the end become stable.

01:15:45.000 --> 01:15:50.000
Once you've timed all of that with a stopwatch,

01:15:50.000 --> 01:15:56.000
then you know how long you're going to have to delay at a reload to make sure.

01:15:56.000 --> 01:16:01.000
Typically what you can do, folks, is just measure the boot time.

01:16:01.000 --> 01:16:04.000
How long does it take to boot the iOS?

01:16:04.000 --> 01:16:09.000
And then if that took two minutes, add another one minute, so time and a half.

01:16:09.000 --> 01:16:10.000
So, add another minute to it.

01:16:10.000 --> 01:16:14.000
If it took three minutes, add another minute and a half to it.

01:16:14.000 --> 01:16:17.000
And then just wait a little longer.

01:16:17.000 --> 01:16:20.000
There's no reason for you to just jump back into the active role

01:16:20.000 --> 01:16:23.000
when somebody is already doing okay with it.

01:16:23.000 --> 01:16:24.000
That's what these are for.

01:16:24.000 --> 01:16:27.000
Keep an eye on those for the certification exam.

01:16:27.000 --> 01:16:28.000
All right.

01:16:28.000 --> 01:16:32.000
Authentication, something we might want to consider with HSRP.

01:16:32.000 --> 01:16:37.000
So, HSRP supports clear text authentication and MD5 authentication.

01:16:37.000 --> 01:16:40.000
So, you just do it right under the interface configuration.

01:16:40.000 --> 01:16:48.000
So, something like standby 10, and then you go type in authentication,

01:16:48.000 --> 01:16:51.000
and then you can do MD5 or plain text authentication.

01:16:51.000 --> 01:16:55.000
So, if we went MD5, I would type in MD5.

01:16:55.000 --> 01:16:58.000
And then we can either do a key chain or a key string.

01:16:58.000 --> 01:17:04.000
So, a key chain is another feature in Cisco iOS where you actually build like a chain,

01:17:04.000 --> 01:17:07.000
a chain for keys.

01:17:07.000 --> 01:17:09.000
Most of us don't have key chains anymore.

01:17:09.000 --> 01:17:14.000
Do you remember a time when you would actually have a key chain?

01:17:14.000 --> 01:17:22.000
And on that key chain, you would have like 5, 6, 7, 8, 9, 10 keys on it for everything you did?

01:17:22.000 --> 01:17:24.000
Well, that's what we're talking about.

01:17:24.000 --> 01:17:27.000
I could create a key chain, and on that key chain, I have many different keys.

01:17:27.000 --> 01:17:33.000
And so then I can call the key from that key chain when I'm doing HSRP.

01:17:33.000 --> 01:17:34.000
That's all it is.

01:17:34.000 --> 01:17:38.000
Or I could just have one key directly created right here.

01:17:38.000 --> 01:17:40.000
That's where you type in key string.

01:17:40.000 --> 01:17:43.000
So, I type in my key string.

01:17:43.000 --> 01:17:48.000
My key string, I'm just going to type in Cisco Rocks.

01:17:48.000 --> 01:17:49.000
And then there we go.

01:17:49.000 --> 01:17:55.000
So, I'm going to copy and paste that over.

01:17:55.000 --> 01:18:00.000
See, you can already see I got a message, bad authentication, because I'm doing authentication

01:18:00.000 --> 01:18:02.000
and they're not doing authentication.

01:18:02.000 --> 01:18:03.000
So, take a peek.

01:18:03.000 --> 01:18:04.000
Right now, you see that?

01:18:04.000 --> 01:18:07.000
I'm active.

01:18:07.000 --> 01:18:13.000
Okay.

01:18:13.000 --> 01:18:16.000
It is putting itself in a standby state.

01:18:16.000 --> 01:18:20.000
Let's just double check that.

01:18:20.000 --> 01:18:21.000
Nope, it's active.

01:18:21.000 --> 01:18:22.000
Look at that.

01:18:22.000 --> 01:18:23.000
It's active.

01:18:23.000 --> 01:18:27.000
So, both routers are active right now.

01:18:27.000 --> 01:18:28.000
Yeah, both routers are active.

01:18:28.000 --> 01:18:30.000
See?

01:18:31.000 --> 01:18:33.000
So, bad authentication, both routers are active.

01:18:33.000 --> 01:18:35.000
Bad group numbers, both routers are active.

01:18:35.000 --> 01:18:37.000
Bad IPs, both routers become active.

01:18:37.000 --> 01:18:38.000
Things like that can happen.

01:18:38.000 --> 01:18:42.000
So, on the exam, if you ever see two routers in the same group are both active, that means

01:18:42.000 --> 01:18:44.000
you've got a configuration problem on your hands.

01:18:44.000 --> 01:18:45.000
Figure out what it is.

01:18:45.000 --> 01:18:47.000
It could be authentication related, group number related.

01:18:47.000 --> 01:18:49.000
It could be related to IP address.

01:18:49.000 --> 01:18:53.000
Look for things like that.

01:18:53.000 --> 01:18:54.000
All right.

01:18:54.000 --> 01:18:55.000
So, let me copy and paste that in.

01:18:55.000 --> 01:18:57.000
Interface VLAN 10.

01:18:57.000 --> 01:18:58.000
Oh, no.

01:18:58.000 --> 01:19:04.000
We don't want that.

01:19:04.000 --> 01:19:07.000
We should say once I get that sorted out, we should go back to normal.

01:19:07.000 --> 01:19:08.000
This should be standby.

01:19:08.000 --> 01:19:14.000
The other one should be active.

01:19:14.000 --> 01:19:16.000
Actually, do we still have R1's interface down?

01:19:16.000 --> 01:19:17.000
Yeah.

01:19:17.000 --> 01:19:24.000
So, DSW-2 should – actually, DSW-2 was active to begin with because R1's interface was

01:19:24.000 --> 01:19:25.000
down, folks.

01:19:25.000 --> 01:19:26.000
We had never brought it back up.

01:19:26.000 --> 01:19:35.000
But you can see DSW-1 promoted itself to active because it felt like it was in its own group

01:19:35.000 --> 01:19:36.000
and the other one didn't exist.

01:19:36.000 --> 01:19:39.000
So, it promoted itself to active.

01:19:39.000 --> 01:19:42.000
Even though R1 was down, we still had that.

01:19:42.000 --> 01:19:46.000
So, I'm standby now, but I should go to active because my priority is going to be

01:19:46.000 --> 01:19:48.000
higher and all that stuff.

01:19:48.000 --> 01:19:50.000
So, we'll let that cook for just a bit.

01:19:50.000 --> 01:19:51.000
All right.

01:19:51.000 --> 01:19:53.000
So, that is authentication.

01:19:53.000 --> 01:19:58.000
And lastly, versions, something to keep in mind here.

01:19:58.000 --> 01:20:03.000
When it comes to versions, you've got HSRP version 1, which is what I just taught to you.

01:20:03.000 --> 01:20:10.000
Version 1 supports groups 0 to 255, so 256 total groups.

01:20:10.000 --> 01:20:19.000
But version 2 supports more groups and IPv6.

01:20:19.000 --> 01:20:20.000
Right?

01:20:20.000 --> 01:20:26.000
So, for the exam, make sure you know that for IPv6, you've got to go to version 2.

01:20:26.000 --> 01:20:28.000
So, how do you go to version 2?

01:20:28.000 --> 01:20:31.000
It's pretty straightforward.

01:20:31.000 --> 01:20:45.000
You're going to type in standby 10 version.

01:20:45.000 --> 01:20:46.000
Okay.

01:20:46.000 --> 01:20:48.000
So, version is for all groups.

01:20:48.000 --> 01:20:51.000
So, no matter what, standby version is going to be for all groups.

01:20:51.000 --> 01:21:01.000
So, I'll do version 2 there, version 2 there.

01:21:01.000 --> 01:21:02.000
All right.

01:21:02.000 --> 01:21:03.000
There you go.

01:21:03.000 --> 01:21:06.000
So, no matter what group I have on that device, we're now version 2.

01:21:06.000 --> 01:21:09.000
On that interface, I should say.

01:21:09.000 --> 01:21:10.000
All right.

01:21:10.000 --> 01:21:13.000
What I wanted to point out to you, though, is that notice how we're reinitializing.

01:21:13.000 --> 01:21:14.000
You see that?

01:21:14.000 --> 01:21:15.000
We're reinitializing.

01:21:15.000 --> 01:21:18.000
Why do we have to reinitialize with this?

01:21:18.000 --> 01:21:23.000
Well, it's because if we type in do show standby, you're going to see that the MAC address has totally changed.

01:21:23.000 --> 01:21:26.000
So, I want you to remember that MAC address now.

01:21:26.000 --> 01:21:32.000
00000C9FF.

01:21:32.000 --> 01:21:35.000
9FF.

01:21:35.000 --> 01:21:44.000
So, if you see 9FF, that is HSRP version 2, and I have it right there on the slide for you.

01:21:45.000 --> 01:21:46.000
Why did they have to change it?

01:21:46.000 --> 01:21:51.000
Because of this.

01:21:51.000 --> 01:21:53.000
See the triple X?

01:21:53.000 --> 01:21:58.000
We need three hexadecimal numbers now for the group number.

01:21:58.000 --> 01:22:09.000
So, in our case, our group is going to be 00A because it is group 10.

01:22:09.000 --> 01:22:12.000
That changes.

01:22:12.000 --> 01:22:15.000
So, if you switch from version 1 to version 2, the MAC address changes.

01:22:15.000 --> 01:22:17.000
Oh, also the multicast address changes.

01:22:17.000 --> 01:22:18.000
So, remember what I said.

01:22:18.000 --> 01:22:21.000
Hellos were using 224002.

01:22:21.000 --> 01:22:26.000
Well, now they're using 22400102.

01:22:26.000 --> 01:22:29.000
Things to keep in mind.

01:22:29.000 --> 01:22:30.000
All right.

01:22:30.000 --> 01:22:31.000
So, that is HSRP.

01:22:31.000 --> 01:22:34.000
That is a lot.

01:22:34.000 --> 01:22:36.000
But we've got that covered now.

01:22:36.000 --> 01:22:37.000
Question.

01:22:37.000 --> 01:22:41.000
If authentication doesn't match and they think they're in their own groups, both would try to use the shared IP.

01:22:42.000 --> 01:22:43.000
Yeah, exactly.

01:22:43.000 --> 01:22:45.000
And that causes conflicts, right?

01:22:45.000 --> 01:22:52.000
So, if you have authentication issues, you have IP issues, you have, you know, whatever issues you have configuration, it really causes problems.

01:22:52.000 --> 01:22:59.000
Because, for example, if you had two different IPs as part of the group, then they're both going to make themselves active because they both want to be active for that IP.

01:22:59.000 --> 01:23:07.000
Now, even though the end user is given like 10.0.0.254, and that points to whoever is active at the time, that would be DSW1 as an example.

01:23:07.000 --> 01:23:21.000
Well, if DSW2 is using 10.0.0.253 as a virtual IP because you goofed it up and you typed in the wrong number, well, then when there's a failover or anything happens, well, then that's the wrong IP.

01:23:21.000 --> 01:23:27.000
And so, there is going to be a conflict there, and then things break down on you during any type of failover scenario.

01:23:27.000 --> 01:23:29.000
And you would get warning messages to that.

01:23:29.000 --> 01:23:30.000
It's not going to work.

01:23:30.000 --> 01:23:31.000
It's bad.

01:23:31.000 --> 01:23:33.000
A lot of syslog messages will show up to warn you.

01:23:33.000 --> 01:23:39.000
But on the exam, they're not going to show you syslog messages ever unless they're testing you on syslog messages.

01:23:39.000 --> 01:23:48.000
So, it's important to realize that at any time, if you see two devices that are active, I immediately want you to look at things like, are the IPs accidentally configured differently?

01:23:48.000 --> 01:23:51.000
Is the group number accidentally configured differently?

01:23:51.000 --> 01:23:54.000
Is authentication accidentally configured differently?

01:23:54.000 --> 01:23:56.000
Those are the things to really take a look at.

01:23:56.000 --> 01:23:59.000
All right.

01:23:59.000 --> 01:24:02.000
HSRP fun.