All language subtitles for Free-CCNA-First-Hop-Redundancy-Protocols-Day-29-CCNA-200-301-Complete-Course_en

This is a free, complete course for the CCNA.

If you like these videos, please subscribe\n

Also, please like and leave a comment, and\n

In this video we will cover all you need to\n

This isn’t the name of a specific protocol,\n

FHRPs you should be aware of for the CCNA.

Let’s check the exam topics list.

Here it is, topic 3.5, ‘describe the purpose\n

there should be an ‘s’ on the end there.

There is no mention of configuration, so you\n

However, in this video I will show you basic\n

can try it out in the next lab video.

Even if you don’t need to know the configurations\n

will help you understand how these FHRPs work.

Here’s what we’ll cover in today’s video.

First up, I’ll introduce the purpose of\n

Then I’ll introduce three different FHRPs.

HSRP, hot standby router protocol.

VRRP, virtual router redundancy protocol.

And GLBP, gateway load balancing protocol.

It may seem like a lot to learn about three\n

just need to be able to make basic comparisons\n

Finally we’ll spend a few minutes learning\n

After the quiz at the end of the video I will\n

for CCNA, a set of practice exams for the\nCCNA.

I studied using ExSim when preparing for both\n

To get ExSim, follow the link in the video\ndescription.

I used this same diagram back in Day 20 when\n

the concept and importance of redundancy in\nnetworks.

For example, if there is only one connection\n

failure or something else, these PCs will\n

In your home, losing Internet access for some\n

For most modern businesses, however, it would\nbe a big problem.

So, we can use redundant connections to the\nInternet like this.

Notice I’ve added some device names and\n

to make things easier to talk about.

Now if this connection fails PC1 can use this\n

This could be, for example, a slower and cheaper\n

But let’s stop and think about this, because\nit’s not so simple.

In this network, let’s say R1’s IP address\n

So that means each PC is configured with the\n

So, anytime these PCs need to send traffic\n

But what happens if R1 goes down for some\n

Fortunately, there is a backup router connected\n

Pause the video and think about it for a minute.

The PCs’ default gateway is still set to\n.254, R1’s address.

Although R2 is available as a backup, the\n

they should switch to using R2 as their default\ngateway.

If a PC needs to send traffic over the Internet,\n

So, how can we cause R2 to automatically become\n

That’s the role of a first-hop redundancy\nprotocol, an FHRP.

Here’s a brief explanation of FHRPs from\nWikipedia.

‘A first hop redundancy protocol (FHRP)\n

designed to protect the default gateway used\n

to provide backup for that address; in the\n

backup router will take over the address,\n

The name ‘first-hop’ redundancy protocol\n

‘first hop’, the first router in the path\n

The two routers share a VIP, a virtual IP\n

You configure the PCs in the network to use\n

instead of the actual IP address of R1.

Now, the routers have to negotiate their roles\nwith each other.

They send multicast ‘Hello’ messages to\neach other, like this.

Okay, so what roles did they negotiate?

Well, one of them, let’s say R1, will become\nthe active router.

The other, R2, will become the standby router.

Note that the actual terms, like active and\n

used, because as I showed you before there\n

So, R1 is the active, meaning it will act\n

R2 is the standby, meaning it will not function\n

If R1 does fail, it will automatically take\n

So, let’s say we set up our FHRP here in\n

traffic to a destination in another network.

I need to send traffic to a destination in\nanother network.

My default gateway is 172.16.0.252, but I\n

I will send an ARP request to learn the MAC\n

I haven’t mentioned ARP in a while in this\n

the MAC address of a particular IP address.

In order for PC1 to encapsulate the packet\n

it has to know the default gateway’s MAC\naddress.

So, PC1 will make an ARP request like this,\n

Remember that the ARP request message is broadcast.

So, it will be sent over the network like\n

Fortunately spanning tree prevents a broadcast\n

So, both R1 and R2 have received the ARP request,\n

172.16.0.252, the one in the ARP request.

R1 is the active router and R2 is the standby\n

R1 will send a unicast ARP reply like this.

My MAC address is...’, and then it will\n

That’s right, not only is a virtual IP address\n

Each FHRP uses a different virtual MAC address,\n

So, the ARP reply is sent to PC1.

Now PC1 knows the MAC address of its default\ngateway.

So let’s say PC1 needs to send some traffic\n

What will the source and destination fields\n

The source IP will be PC1’s, 172.16.0.1.

The destination IP will be the Google server,\n8.8.8.8.

The source MAC will be PC1’s MAC address.

And the destination MAC address will be the\n

The frame will be sent to R1, and then the\n

There is no default gateway for the network.

But after a few seconds, R2 will think ‘I\n

from R1 recently...I will become the Active\nrouter!’.

So R2 is now the active router.

But how does it tell the other devices to\n

Note that the end hosts, the PCs, actually\n

The entry in the PC’s ARP table is like\n

So, what needs to be updated to make traffic\n

R2 needs to make the switches update their\nMAC address tables.

Remember how switches update their MAC address\ntable.

When they receive a frame they check the source\n

the information in the MAC address table.

So, R2 needs to send frames with a source\n

To do this, it will send ‘gratuitous ARP’\nreplies.

Gratuitous ARP is probably outside of the\n

Gratuitous ARP messages are ARP replies sent\n

Normally ARP replies are sent in reply to\n

ARP reply messages are sent without receiving\nan ARP request.

Here’s another difference between gratuitous\n

The frames are broadcast to the MAC address\n

Because they are broadcast, all switches will\n

So, R2 will send gratuitous ARPs like this.

They will be broadcast throughout the network,\n

The switches will then update their MAC address\ntables.

SW2 will learn that it can now reach the virtual\n

the same thing, and so will SW3 and SW4.

Now R2 is the active router, and all of the\n

Let’s say PC1 wants to send traffic to the\n

The frame and packet are exactly the same\nas before.

Source IP is PC1’s, Destination IP is the\n

destination MAC is the Virtual MAC.

However, this time the frame will be sent\n

Now, what if R1 comes online again?

Will it become the active router once again?

No, it will become the standby router.

Like I said about the DR and BDR in OSPF,\n

The current active router will not automatically\n

However, although this is the default behavior,\n

R2 and take back its active role automatically,\n

Okay, so that was a basic overview of how\n

I haven’t talked about any specific FHRPs\n

Before moving on to explain a few specific\n

A virtual IP is configured on the two routers,\n

Each FHRP uses a different format for the\n

An active router and a standby router are\nelected.

Again, different FHRPs use different terms,\n

setup, with two active routers at the same\n

Next, end hosts in the network are configured\n

The active router replies to ARP requests\n

destined for other networks will be sent to\nit.

It functions as the default gateway for the\nnetwork.

If the active router fails, the standby becomes\n

The new active router will send gratuitous\n

It now functions as the default gateway for\nthe network.

If the old active router comes back online,\n

It will become the standby router.

This is like the DR and BDR in OSPF, they\n

even if another router is configured with\na higher priority.

But, in FHRPs you can configure ‘preemption’,\n

its old role if it comes back online.

Okay, sorry for the wall of text.

Before moving on to a few specific FHRPs,\n

once more to make sure you understand the\n

N ow I’ll give a brief overview of\nthree major FHRPs.

The functionality of each is very similar,\n

sure you learn these details for the exam.

First up, HSRP, Hot Standby Router Protocol.

HSRP is Cisco proprietary, so it only runs\non Cisco devices.

You can’t run it on Juniper routers, for\nexample.

In HSRP, an active and standby router are\nelected.

These are the two terms I used previously,\n

There are two versions of HSRP, version 1\nand version 2.

Version 2 adds IPv6 support, and increases\n

You’ll see what a group is when we configure\nHSRP later.

In our example today, there was just one subnet,\n

But in situations with multiple subnets and\n

IP address for each subnet, because each subnet\n

Each of those virtual IPs is configured in\n

Anyway, as I said you’ll see how that works\nlater.

Remember how I explained that the routers\n

224.0.0.2 for version 1, and 224.0.0.102 for\nversion 2.

It may seem not so important, but try to remember\n

Next up, the virtual MAC address formats.

These are tougher to remember, but make sure\n

Use the flashcards, try writing them from\n

So, version 1 uses 0000 0c07 ac, followed\nby the group number.

So, in my previous example let’s say I configured\n

If using HSRP version 1, what would be virtual\nMAC address be?

It’s 0000 0c07 ac01, because the group number\nis 1.

Now, HSRP version 2 uses the format 0000 0c9F\n

Note that 3 hexadecimal digits are now available\n

Anyway, if group number 1 is used, what would\n

One last point, in a situation with multiple\n

active router in each subnet to load balance.

Remember what I said in previous videos about\n

You can configure a different root bridge\n

Well, when you configure multiple HSRP groups,\n

a different active router in each subnet and\nVLAN.

For example, R1 could be the active router\n

be the standby in VLAN1 and active in VLAN2.

This is probably beyond what you need to know\n

Let’s say VLAN1 is assigned to hosts in\n

R1 and R2 have their own IP addresses in VLAN1,\n

which is used as the default gateway of the\nsubnet.

R1 is the active router and R2 is the standby\nrouter.

Then, 172.16.2.0/24 is the subnet for VLAN2.

R1 and R2 have their own IP addresses in VLAN2,\n

They also share the virtual IP address 172.16.2.252,\n

R2 is the active router and R1 is the standby\nrouter.

Now traffic can be load balanced over the\n

R2 as the default gateway of the subnet, and\n

So, that’s a basic overview of HSRP.

Although it can’t load balance within a\n

active router in each subnet so that traffic\n

Let’s move on to the next FHRP.

Next up is VRRP, Virtual Router Redundancy\nProtocol.

Unlike HSRP, it’s an open standard, so it\n

Cisco routers run it too, so you can use either\nHSRP or VRRP.

Honestly, in terms of functionality they are\n

Instead of an active and standby router, a\n

The function is the same, just the names are\ndifferent.

Master is equivalent to HSRP’s active, and\n

The IPv4 multicast address used is different\n

Again, use the flashcards to remember little\ndetails like this.

The virtual MAC address format is different,\ntoo.

0000 5e00 01, followed by the VRRP group number.

Let’s try a bit more of a challenge.

What if I configured VRRP group 200, instead\nof group 1.

What would the virtual MAC address be?

You have to convert 200 to hexadecimal.

Pause the video to try that, do a Google search\n

Okay, the answer is 0000 5e00 01c8.

Hexadecimal c8 is equal to 200 in decimal.

Just like HSRP, although VRRP can’t perform\n

it can load balance between different subnets\n

Here’s the same diagram as before, showing\n

All that’s different is that ‘master’\n

Before moving on, I just want to mention one\n

Notice that all hosts in VLAN1 are in the\n

in VLAN2 are in the same subnet, 172.16.2.0/24.

This is how subnets and VLANs are used.

Subnets divide the network at Layer 3, and\n

work together, each subnet being its own VLAN.

You might have noticed that throughout this\n

Before moving on to the last FHRP, here’s\n

In terms of functionality, they’re nearly\nthe same.

But remember the different terminology, multicast\n

Also remember that HSRP is Cisco proprietary,\n

run on any network device that supports it.

Next up, we’ll take a look at GLBP.

The final FHRP you should be aware of is GLBP,\n

This one is a bit different than HSRP and\nVRRP.

Like HSRP, it is Cisco proprietary, it only\n

Here’s the big difference: it load balances\n

For example, if PC1 and PC2 are both in VLAN1,\n

PC2 can use R2 as its default gateway.

This is different than HSRP and VRRP, in which\n

same router as the default gateway for the\nsubnet.

In GLBP, a single AVG, Active Virtual Gateway,\n

Then, up to four AVFs, active virtual forwarders,\n

Each AVF acts as the default gateway for a\n

So, load balancing is achieved within a single\nsubnet.

The multicast IPv4 address is 224.0.0.102,\n

The virtual MAC address format is 0007 b400,\n

For example, what is the virtual MAC address\n

So, the functions of GLBP are a bit more complicated\n

the CCNA remember that GLBP allows multiple\n

a single subnet, and remember the multicast\n

It might seem not so important, but for the\n

Here’s that chart again, with GLBP filled\nin.

If you remember the basic characteristics\n

information in this chart, you’ll be ready\n

However, as a little extra, I’m going to\n

HSRP, so we can try it out in a lab in the\nnext video.

Although configuring HSRP isn’t part of\n

experience will help you understand how it\nworks.

So let’s do some basic configurations for\nHSRP.

To fit everything on the page and show the\n

We’ll be focusing on configuring R1 and\n

gateway address for the 172.16.0.0/24 subnet.

I’ve already configured all of the interface\n

Note that I’m using .254 as the virtual\n

So, let’s get started configuring R1.

HSRP is configured directly on the interface,\nG0/0 in this case.

Make sure you configure it on the correct\n

it is acting as the default gateway for.

HSRP is configured with the STANDBY command.

I used the question mark to see what options\nare available.

There are many more than this, but the one\n

Note that HSRP version 1 is the default, so\n

If using HSRP version 2, this range would\nbe 0 through 4095.

Actually, let me show you how to change it\nto version 2.

The command is STANDBY VERSION 2.

If I check the STANDBY command again, you\n

This simple network is using just a single\n

You don’t have to do this, it’s not a\n

to the VLAN number used for the subnet.

Note that this group number does have to match\n

So, I used the question mark again to check\n

First up, you configure the virtual IP with\n

by the IP address you want to use as the default\ngateway.

Then I used the PRIORITY command, as you can\n

It’s used to determine which router will\nbe the active router.

The active router is determined in this order.

First, the router with the highest HSRP priority\n

If the routers have the same priority, the\n

In this case R1’s IP address, 172.16.0.253,\n

So, even without configuring the priority\n

Finally, I enabled ‘preemption’.

Enabling the PREEMPT command causes the router\n

another router already has the role, although\n

For example, let’s say R1 is the active\n

If an error causes R1 to restart, R2 will\n

When R1 comes back online, if preemption is\n

However, with preemption enabled R1 will take\n

Note that you only need to configure preemption\n

Even if I don’t configure preemption on\n

First up, I enabled HSRP version 2 on R2’s\nG0/0 interface.

This is important, HSRP version 1 and version\n

2, R2 must use version 2 also or there will\nbe problems.

Next I configured the same virtual IP as on\nR1, 172.16.0.254.

The next two commands, setting the priority\n

R1 already has a higher priority than R2,\n

But I configured them anyway, so the configuration\n

Finally let’s take a look at the output\nof SHOW STANDBY.

This is the output from both R1 and R2, let’s\n

First up, notice the HSRP group number of\n

The state is active, because R1 is the active\nrouter.

Here the virtual IP address we configured\nis displayed.

These two lines display the virtual MAC address,\n

We didn’t configure these so they are the\ndefault values.

Preemption is enabled, because we configured\nSTANDBY 1 PREEMPT.

Active router is local, because R1 itself\nis the active router.

The standby router is 172.16.0.252, which\nis R2.

And finally here is the priority value of\n

If you want to take a look at the output of\n

Okay, that’s all we’ll cover about HSRP\n

Before moving on to the quiz, let’s review\n

First I gave an introduction to the purpose\n

a redundant default gateway for a subnet.

Then, I briefly introduced three different\n

Make sure to learn the basic characteristics\n

multicast IP addresses and virtual MAC addresses.

Then I introduced some very basic HSRP configuratons.

You probably won’t be asked about these\n

on practice will help you understand the topic,\n

lab, taking a look at preemption and such.

Here are the commands we used.

STANDBY VERSION 2, to configure the router\n

STANDBY IP, to set the virtual IP address\n

STANDBY PRIORITY, to help control which router\n

And STANDBY PREEMPT, to cause the active router\n

Remember to watch until the end of today’s\n

for CCNA, by far the best practice exams you\n

You can get Boson ExSim from the link in the\nvideo description.

Okay, let’s go to question 1 of the quiz.

Which of the following is an HSRP version\n1 virtual MAC address?

A, B, C, or D. Pause the video now to think\nabout your answer.

The answer is D, 0000 0c07 acab.

The HSRP version 1 virtual MAC address format\n

It’s 171, so in this case HSRP group number\n171 was used.

As for the incorrect answers, options A and\n

and option B does not follow any FHRP virtual\n

Which of the following is a VRRP virtual MAC\naddress?

A, B, C, or D. Pause the video to think about\nyour answer.

The answer is A, 0000 5e00 010a.

The VRRP virtual MAC address format is 0000\n

What is hexadecimal 0a in decimal?

It’s 10, so in this case VRRP was configured\n

Option B is a GLBP virtual MAC address, option\n

and option D does not follow any FHRP virtual\n

Okay, let’s go to question 3.

Which of the following are valid VRRP router\nroles?

Or F, active virtual forwarder.

Pause the video to think about your answers.

The answers are B, backup and D, master.

A, active and E, standby are HSRP router roles.

C, active virtual gateway and F, active virtual\n

VRRP uses master and backup routers.

When the HSRP standby router becomes the new\n

Pause the video to think about your answer.

The answer is B, gratuitous ARP.

Some other answers are not totally incorrect,\n

In Cisco’s questions, at the end it usually\n

That’s because some of the options aren’t\n

For example, option A is ‘HSRP Hello’.

Routers using HSRP always send Hello messages.

So, when the HSRP standby router becomes the\n

HSRP hello messages, so A isn’t totally\nincorrect.

However B is the better answer, because it\n

it becomes the new active router.

I told you that gratuitous ARP messages are\n

However, B is the better answer because it’s\nmore specific.

So, when taking the CCNA exam make sure you’re\n

the other options seem like they might be\ncorrect.

Which of the following statements accurately\ndescribes HSRP?

A, it allows you to configure a different\n

B, it allows multiple routers to load-balance\n

C, it provides a redundant default gateway\n

Or D, each router selects a unique virtual\nIP and MAC address.

Pause the video to think about your answer.

The answer is C, it provides a redundant gateway\n

Although you can configure a different active\n

it doesn’t provide load balancing for hosts\nin a single subnet.

To do that, you would need to use Cisco’s\n

Okay, that’s all for the quiz.

Let’s move on to a bonus question in Boson\nExSim for CCNA.

Okay, here's today's Boson ExSim practice\nquestion.

By the way, I noticed that you can zoom in\n

Why of the following statements are true regarding\nHSRP?

Okay, so I'll let you read these options yourself.

Pause the video here, read the options, and\n

Okay, hopefully you got the answers.

A, one router is elected as the master router,\n

That is incorrect, master and backup, that\n

B, in an HSRP group only one virtual IP address\n

In a single HSRP group only one virtual MAC\naddress is used.

Okay, C. One router is elected as the active\n

That is correct, I believe, about HSRP.

D, in an HSRP group only one virtual IP address\n

I think, but let's check option E as well.

All routers in an HSRP group can participate\n

Okay, that is not true for HSRP, but it is\ntrue for GLBP.

Okay, so I think C and D are correct.

So here is Boson's explanation, quite detailed.

You can pause the video here if you want to\n

They also have a reference to some Cisco documentation\n

And it states the category of the exam topics\n

Okay, so that's an example question from Boson\nExSim.

Boson ExSim is a great set of practice exams\nfor the CCNA.

I used it when studing for my CCNA, and I\n

my CCNP, and I highly recommend them.

So if you want to get a copy of Boson ExSim\n

There are supplementary materials for this\nvideo.

There is a flashcard deck to use with the\nsoftware ‘Anki’.

There will also be a packet tracer practice\n

That will be in the next video.

Sign up for my mailing list via the link in\n

the flashcards and packet tracer lab files\nfor the course.

Before finishing today’s video I want to\n

Recently I’ve noticed an increase in the\n

to all of you, both JCNA and JCNP-level members.

Your support helps me keep making and releasing\n

This is the list of JCNP-level members at\n

21st 2020, if you signed up recently and your\n

Please subscribe to the channel, like the\n

with anyone else studying for the CCNA.

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