the next topic of discussion
is generally speaking, this this particle falls under the class. Reporter calls call first hop redundancy protocols. Specifically out of those were going to be covering hot standby routing protocol, which is a Cisco Proprietary protocol. Let's look at this land. Host one and host two are connected over land,
the I P address being 1 51 1 45 0
and we have to routers
with the I. P is being 1 51 1 45 2534 hour one and not 2544 Outer too.
And they're also connected on the same land
and both of whom have cereal links to the outside world or to the SP on 2000 on Route A one and both rot if Host one was configured with a default gateway
pointing towards the fastest in at 00 interface of Router one
and host to was also configured
with the default gateway pointing to the 1 51 1 45 253 address and rotter to was not present here.
Then, if outer one failed, Host one and host who would boat lose connection to the outside world.
That's where just heart becomes it or hot standby routing. Pirkle. The general idea here is
that we're going to create a virtual router combined these two routers into one big virtual router, and we're gonna assign it a virtual I p address and a virtual Mac address.
So we create a virtual router and that ritual router. Let's call it a router. Acts is going to have an I. P address
Mac address, and then we're gonna point the default gateways for host one and host to to that virtual I p address.
So what will happen is
one of these routers is going to become the active router. Let's say a router one becomes the active router if we're active
and rather chew is the standby router.
and router, one is going to be the one that is actually fording for host one and host to if they're sending traffic out to the Internet.
And if Router One were to fail,
the switch from our 12 router to is going to happen flawlessly, and router to is gonna pick up and become the active and start forwarding for host one and host too.
Host One and Host two are never gonna notice that router one is down because in their default, Gateway asked their default gateway. We're not gonna 10.2 facets in at 00 for outer one or faster than at 00 over out or to not the 253 or the 254 address.
But we're gonna pick a separate address
that we're gonna point to that belongs to the virtual router. So if any one of the physical devices were to fail,
is going to take over the active role. The standby device is gonna take over the active role. So let's pick a virtual I p
Now a few other things that we need to remember or make note off with it just RP.
Once it just RP is configured Router one and two in that diagram are going to send each other hello messages to keep the link alive and to make sure that all the routers
that are going to form this one big virtual router are alive and well.
So the hello time or the time period between hellos is three seconds.
Then there's the whole time. This is the number of seconds. I will wait for you to send me a hello before I consider you down.
So, let's say a router one and two exchanging hellos between each other every three seconds.
Knife Router one does not hear. Well, let's say router to does not here. Ah, hello from router one
for 10 seconds around her too, is going to consider rather one down and become the active Ratter and take over the rule for affording traffic from Host one and host due to the Internet.
There's also a timer called active timer.
when the standby router receives hello from the active router. So when the standby router receives a hello from the active router, active timer is reset every time. Because the sand by router continuously needs feedback to know that the active router is alive and well,
since we're going to assign
a virtual I p address.
The virtual router, The big router. The combination of Router one in Router two. We need a virtual mac.
Now the virtual max just RP is created automatically
the 1st 24 bits off the work. Oh, Mac are the vendor I d.
So Cisco has its own vendor. I d Jennifer has its own vendor. I d Nortel has its own vendor i d sort of Microsoft and Apple.
So the 1st 24 best that 00000 c would be the vendor I d
note that any Mac address. If you were given the list of Mac addresses and you were asked which one of these Mac addresses is an H S r P address
the interest R p I d never changes from 07 a. C. So whenever you see 07 a C after the 1st 24 bets, you know that this is a sorry Virtual Mac,
the last to the last two ex characters
in the Virtual Mac represent the H S R P group. So this says zero A, which means a stands for 10 in hacks. So this means this is S R p group number 10.
So let's go get our configurations
I'm simply going to going to the interface facet in at 00 right here
and I'm going to say stand by. Stand by. 10. I'd be 1 51 1 $45. 10.
Which is the address we picked to assign to the virtual router.
As soon as I had enter on this command, this virtual Mac is going to be automatically created
then for administrative purposes. The second command is not really necessary. I can name my stand by
So the stand night 10. The 10 is simply the group I D.
And you can pick any number between I believe one and 255
This number just needs to be same on all the routers that you need to be in the same group. So this this number cannot vary between routers. As long as you put the routers in the same group, they'll talk to each other.
Then again, standby group number 10 name. And then whatever name you picked for it again, The second command is not necessary.
it's just done for administrative purposes
on router to also I'm gonna sign the same stand by 10 group exact same group because both routers are gonna be the same group
and then the same might be 1 51 1 45 10 Which is a virtual routers I p address. At which point when I hit enter again The Virtual Mac address is going to be created.
Then the next command stand by 10 Priority 105
and on writer too. I said stand by 10 Priority 100.
Now the priority value can very between one and 255
I want router one to be the active router and router to to stand by and wait for outer one to go down before it becomes active.
if I pick priority 1054 out of one and Priority 100
Rather one becomes the active router and rotter to becomes the standby rather
now the default priority for interest RP is 100. So I didn't really need this command here. I just put it down there to show you
when If I leave out the standby priority command from both routers, what happens then?
Well, whichever route or you configure first becomes the active router
whichever router you configure 2nd 3rd and fourth becomes they become the stand, but routers In this case I choose. I want router one, regardless of whether it's configured first or second or third to be the active router and increased its
So in this case, up until now. Router oneness fording traffic
for the virtual router
right now So well, these matters acting as one, the virtual router. But within the virtual router, the physical device that is forging the traffic is rather one
stand back router, which is a round or two, is reading in case Router one goes down. If Route A one goes down, right are two picks up the active router rule.
and it's not covered in detail in the sea. CNN. But I'm gonna go ahead and do it anyways.
Is the interface tracking
Now if you look at this diagram
rounder one and two,
we'll know if f 00 if 00 on both routers, go down and host one and host to will not be able to afford traffic.
But what about this outside link connecting to the outside world? The serial 000 link on rather one and the serial 000 Link on router. To
that, we can monitor with the feature known as interface tracking.
So I've said stand by 10 track Serial 000 on Router one and stand by 10 Track serial 000 on router to
let's say, this link does go down on Route one
now that I'm tracking this link on router one. As soon as this thing goes down, Roger one will automatically Decker Ament. It's priority by 10.
So right now our outer one's priorities 105 You deck lamented. It becomes 95 since its priority becomes 95.
router to take over?
preemption is not allowed in excess RP by default, which means if Router one was the active router, I cannot
take that rule away from Router one
to be eaten for outer to to be able to take that role away from Router one. I actually need to add the command stand by 10 Preempt now in this case, router to will pre enter Outer one's status as the active router and take it away
and become the active rather.
Now what happens if at a later time router one becomes alive and well,
and we know that we spent more money on rather one. It's a better router, and we want Router one to become active again.
Then Router One also needs to be able to preempt router to and take that rule away. Because when router ones comes back, is priority will be reset 105
So we also need to add the command
stand by 10. Preempt on router one. This configuration is a little bit more advanced than what is required for ccn A. However, Cisco kind of
leaves it in a gray area as to how much they cover for S S r p and what might be on the exam. So I went ahead and covered it with you guys Anyways, just in case it shows up on the test, this ends the edges are p lecture