HSRP #CCNA

in this video we're going to discuss first hop redundancy protocols such as hsrp or hot standby writing protocol vrrp and glbp i'm going to start with hsrp because that's the most important for the ccna i wouldn't worry too much about vrrp and glbp for the ccna exam apart from having an understanding of how they different to hsrp for the ccmp encore exam you need to have an understanding of those three protocols you should be able to configure hsrp as an example be able to configure tracking and various other options within hsrp it's also worthwhile knowing about vrrp and glbp for the real world so what does hsrp basically give us or what do first hop redundancy protocols give us think of the name first hop in other words first a router or first layer 3 device if you want to send traffic from a host to a remote host you're going to be sending that traffic to your default gateway at home that could be something as simple as your home router something like this the problem is what happens if this goes down so you might have a simple rider at home and if that goes down or a link goes down it's okay you might start going onto the internet using your cell phone or your mobile phone but in a corporate environment we want to have multiple paths so we want to have some kind of redundancy in the network and the best way to probably learn this is for me just to show you how this works practically and for this example i'm going to use cisco cml which allows you to replicate networks on your computer for the ccna you can practice using packet tracer but cml gives us a lot more information than what you'd get using packet tracer okay so in this topology i've got a pc pc one pc one's ip address is 10 1 1 1. iprout shows us the local routing table on this ubuntu computer as you can see here default gateway is ten one one two five four that's very similar to looking at your ip default gateway on windows or on a mac basically this is the ip address of the router that's gonna allow this pc pc one to ping pc2 pc2 has an ip address of 8.8.8.8 it's on pc1 if i'm paying 8.8.8.8 that works we have ipconnectivity but if i connect to router 1 show ipinterface brief shows us that this is the ip address of the router's gigabit zero zero interface so basically pc1 is sending traffic to pc2 via router one and that's fine except if there's a problem on router 1. so let's ping 82.8.8.8 and then on router 1 as an example i'll simply shut down gigabit zero zero and what you'll notice is the pings fail we're at sequence nine we don't see sequence ten traffic is not being sent pc1 can't send traffic to pc2 anymore if i go back onto router 1 and i know shut that interface what we should see is pc one can ping pc2 again and as you can see we went from sequence 9. i'll just stop that to sequence 38. so a whole bunch of traffic was lost when the router went down pc lost connectivity even though there's an alternate path so if we look at router 2 show ip interface brief it has this ip address and pc1 could send traffic to pc2 using router 2 but it doesn't automatically switch over from router 1 to router 2. to do that we use first hop redundancy protocols such as hsrp so hsrp is quite simple to set up in its most basic form we are going to specify a group number you can specify different groups where you can say this router is going to be the main router for one group and this router is going to be the main router for another group in this case we are using group one and we're going to specify this virtual ip address so previously router 1 was configured with that ip address so that was the ip address of the physical router i'm going to change that ip address now because we want to use a virtual ip address in this example we're going to have three ip addresses rather one will have an ip address router 2 will have an ip address and a virtual router will have a third ip address which is actually the ip address that the clients are going to point to so the clients are going to connect to a virtual router but the traffic is going to be forwarded by what's called the active router and then we'll have a standby router so in this example router 1 and there's an election to determine who becomes the active router in this example let's assume router 1 is the active router it will forward the traffic on behalf of that subnet or that hsrp group if router 1 fails then router 2 will forward the traffic but let's prove that so on router 1 i'm going to change the ip address to 10 1 1 2 5 so give it a different ip address so back on the pc i'm going to clear the arp cache and let's see if it can still ping pc2 and as you can see it can't ping pct i've cleared the op cache because i don't want the pc to remember the mac address of rada1 so at the moment it's not able to ping pc2 so on the router standby specify a group number ranges from 0 to 255. i'll specify group 1. i need to specify the hsrp ipv4 virtual ip address so ip and i'll specify 1011254 i've used the command term mon or terminal monitor to make sure that we're monitoring what's going on we've been told that the console already monitors and notice hsrp state has changed from standby to active so if i type show standby you can see that for group 1 state is active virtual ip address is this notice the virtual mac address this is a virtual mac address for hsrp and the group number that we've specified is group one at the moment the local router is the active router there is no standby or backup router the priority is 100 and that becomes important because we can change priorities the higher the priority the more likely a router is to become the active router by default it's 100 good number to remember if i want to force one router to become active i can increase its number and we'll do that in a moment but notice now before we do anything else can pc1 ping pc2 and the answer is yes i'll clear the screen i'll type ip neighbor notice this mac address is reachable that is the hsrp mac address we told that this mac address is stale let's have a look at the router show interface gigabit zero zero that mac address ending in one f a one is the physical mac address of router one notice the ip address so pc1 is seeing the virtual ip address as reachable and that ip address and mac address is what's going to be used when sending traffic to pc2 okay but that still doesn't help us because if router 1 goes down we still can't send traffic from pc1 to pc2 so what we're going to do on router 2 is do something similar standby make sure the group number is the same make sure that you configure the same ip address and what we should see is the router goes through an election process it's already learned who the active rider is standby right is unknown state is listen at the moment it's gone to speak it went from speak to standby so the state has become standby active routers rather one a local router is the standby router on router 1. shows standby active right is local router 2 is the standby rider now in hsrp the way the election works is highest priority wins if the priorities are the same then typically the highest ip address wins but in this example because router 1 started up without router 2 being there it became the active and rider 2 is not forcing itself to become the active router by basically forcing control to itself so for the exam the answer is is that the rider with the highest priority wins but that's not always true typically it's the first router on the segment that goes to the active state and if another router joins later this router remains the active router but if they both join the segment at the same time so let's say they're both reboot they both come up they're sending messages to one another and then the router with the highest priority will become the active router okay so let's see if this actually works on router one show run interface gigabit zero zero that's the configuration on router one show standby gigabit zero zero this is the group configured on gigabit zero zero state is active local router is active standby router is router two current priority on the local router is a hundred we see something similar on router two show run interface gigabit zero zero that's the command that enables hsrp show standby gigabit zero zero we can see that the local router is the standby router active router is router one okay so on pc1 can we ping 8.8.8.8 which is pc2 on router 1 i'll shut the interface down so active state has gone to init on router 2 notice router 2 is active and on the pc the pings are continuing notice we lost i'll just pause that notice here we lost one ping so sequence number nine dropped 10 sequence 11 worked so one ping was lost in the changeover from router 1 to router 2. now in the next video i'll talk about hsrp in more detail so i'll show you how to set priorities i'll show you how to set up preemption i'll also show you how to monitor an interface so that and if an interface goes down you can reduce the priority of the hsrp router or the active router so that the standby router becomes active hsrp has many many options so we'll look at some more options in a separate video hope you enjoyed this video if you did please like it please consider subscribing to my youtube channel and clicking on the bell to get notifications i'm david bomble and i want to wish you all the very best

Channel: David Bombal

Views: 21,126

Keywords: hsrp, ccna, hot standby router protocol, cisco, ccnp, vrrp, glbp, fhrp, ccie, networking, free ccna, first hop redundancy protocol, virtual router redundancy protocol, gateway load balancing protocol, ccna 200-301, ccna training, cisco ccna, new ccna, ccna certification, ccna 200-301 full course, ccna full course, cisco training, ccna course, ccna study, cisco certification, ccnp switch, cisco certifications, ccna routing and switching, what is vrrp, cisco training videos

Id: zu8wQPffQ8o

Length: 12min 37sec (757 seconds)

Published: Sat Jan 09 2021