OSPF 18 Intermediate Level

right this topology is going to be used to learn multiple features that we have in ospf we have a multi area here between one two row two so between round one throughout the six got three areas we got reachability as well let me show you ping 6.646.6 which is a low back interface of r6 serves 1.201 which is an ip address on the lubeck interface of r1 we are able to reach let me show you the database show ipospf database you can see type 1 say see this area this area has got three routers rotor 1 203 so you are seeing three entries three routers and this router of this area also have got two lan segments two different subnets i told you for each internet segment there will be one designated router in in that case i should see 2dr yet between router 1 and 2 mr two is the designated router because of the highest router id between router two and three three is the designated router because of the highest router id and the below ones are the other area routes these okay this 3.3.3.3 is in area 0. it's in area 0. we have put the loopback interface of this router in areas here it is not in area 1 that is why it is listed under type 3 let's say summary let's say what do you mean i'll show you show ib ospf interface brief if you see here the lubeck 0 is an area 0. that's the reason why it is displayed under type three obviously these things are other area roots five five five six six six thirty four which is three and four areas zero network where it is here 45 56 all or from other areas we don't have type 4 and 5 the reason is we do not we don't have asbr we don't have any asb anymore anywhere so far we'll come to this later we have a lot of other things to do before now let us focus on the virtual link first virtual link [Music] now what it is i was telling you if this area 3 did not connect to area 0 router if it is not going to connect there is no chance of r7 learning the routes of r2 r3 r4 5 6. r7 cannot even learn the standard 12 network because tender 12 is in area one area three can learn about area one or any other area only via it is zero but there is no connection to area zero image really you have to put a virtual link you have to put a virtual link between r1 and r3 only then that is possible not only r7 all right also cannot learn about any other area our six will never learn any network from r3 sorry area 3 r2 r3 r4 or 5r6 from r2 to r6 they will not be aware of any network from area 3 if you don't put virtual link so virtual link is a virtual wire a logical wire unseen wire that connects this r1 and r3 so that r1 will feel that it has got connection as if r2 and r3 is connected see r2 and r3 is connected same feeling r1 will get with r3 r1 will feel that i am connected to a area border router r3 will get a feeling that okay i have connected to area 3. but not via ethernet 0 but via virtual link bl 0 but as one of you said in the previous class this is the physical path by which the packets are going to be pushed the updates ospf updates the route updates from area 3 lsa type 3 from area 3 will be given to area 0 via this physical link but the packets won't get delivered to any of the middle router it gets delivered only to the virtual tunnel endpoint that happens to be router 3 in our case that's the logic this is just used as the forwarding plane r2 is used as just a forwarding plane between aroon and r3 the update sent by r1 the lsa type 3 of area 3 sent by r1 has got no stop in the middle it gets straight to r3 and get delivered in r3 which is an abr and r3 only will take the update and generate lsa type 3 and send to area 1. so area 3 updates are learned on area 1 not from r1 but from r3 likewise the other radius so virtual link is like you connect a wire between this router and this router it's like that now you see r1 is connected to a backbone router but sorry armin i'm not that rich i cannot offer a wire for you but i'll give you a virtual link are you happy okay to an extent but i'm not fully satisfied you know i'm okay yes virtual link is not a permanent solution it's not a happy solution why the type 3 lsa of area 3 reaches area 1 but area 1 can't use it it is simply forwarding it directly to r3 and only area 0 can send the update to r2 which means updates go to area 0 and come back to area 1. the band utilization of the route update is doubled if you do lot of summarization here then okay okay okay but not best one it's okay you know so it is a temporary solution to connect area 3 to area 0. the best solution is as i was putting a physical cable between r1 and r3 you need to do that if possible otherwise you just plug this r8 r7 this entire area from r1 move it to this location i'm connected to r3 directly connect re directly to r3 you know this is easy in three in real world i tell you sometime it will take months to move the little blocks even in our house to move a small domestic router from one route one one room to another room uh it never happens you know five years so you know ten years of seven years back one hole was done on the wall and the fiber was coming in i i want to move it to another hall i don't want that wi-fi device anymore there but i'm just only thinking because i need to put another hole in another direct another part of the building and you call the guy bring him the tool necessary towards the fiber one so and then he will come and crimp it with the special machine the fiber i do not want to take that risk just in a small home or for a domestic router if it takes that long just think about a big organization the policies of digging the ground laying the cable uh procuring new cables fiber cables approval to very difficult i have seen that in many companies it never happens so seeing the design change the design extend the area 0 up to r2 extend r1 up to r7 extend area 1 up to ourselves do something like that or move it fine let us now go to virtual link i'm going to quickly configure the necessary things show ip interface brief on r1 if you see ethernet 0 0 is still not configured interface ethernet 0 slash 0 boom [Music] zero zero and i p o o spf ipospf one area three all right is done show ip interface show show ip interface brief okay show ip ospf interface show ipo spf interface brief i can see this area 3 member and i'm very happy let's go to rotate interface ip ipo spf one area 3 interface ethernet 0 1 ip address 10.18 dot 0.8 if the subnet mask don't match the hello packets will not be accepted the neighborship will come so keep an eye on this net mask always all right we see a neighborship between r8 and r1 but i would not take the updates of our eighth and give it to our two because r1 is not having membership with area zero so alvaro has got no rights no rights to forward the update of area 3 to area 1 even though it's a neighbor sure ipo spf r1 is a neighbor you know r1 will know about aw data data let me show you r1 please tell us show ip route e dot dot ah i know i know i know i need to go to router 8. see it shows it says that i learned through ospf see 110 i know i know but our one won't give iron won't give this update to r2 see sure if you ospf neighbor r102 are really very good friends but i don't want you sure i'd be route he already directed it it says no idea who is this guy he did that's why you need virtual link only area 0 router at least one interface should be a member of area 0 in r1 only then r1 can push the update to other areas that's why we are we are creating that one link the one port at least one port need to be connected to area zero but physical port i don't have a physical connection is not possible i need virtually all right we'll do that let's finish the other route r7 r7 console show ip interface brief no ip address so let us put ip address interface lubeck 0 ip addresses 7.7.7.7 0.0 ipo sp1 area 3 and then interface ethernet zero zero 1078 10.78 255.255.0.0 ipo spf 1 area 3. and that's all i'm expecting a neighbor if the neighbor is not coming i have done some mistake on r8 unknowingly i might have put in areas zeros instead of three show ip ospf interface brief uh i know it's right then what happened 78 uh-uh on r8 i did not configure this e00 interface show ipinterva is brief i didn't even configure interface no ip address 10.78.0.7.8. five zero zero ipo spf 1803 883 333 show ipo spf interface brief all right now will never come yeah why not let's come long back means a little not too long a few minutes okay so if you see r1 knows about r7 also show ip route 7.7.7.7 he says ah i know i know i know very well through ospf i can even ping mr 7777 which is an area three with a source no in the source you cannot be you can't bring in the gutilla you know why this 1.1.1.1 is in area one it won't be advertised it won't be advertised area 3 without area 0. but if you don't source with the lubeck then the thing will happen the reason is is using the exit interface which is is which is in area 3 itself all right r1 even though it knows about 777 can't be pinged with any interface you can ping only with the ethernet 0-0 interface remember this is very important i see a road in my routing table it's not my router router fault it is your outer fault you see my routing table is good i'm not able to ping means it's not my fault ignorance it's ignorance even if you have route in the routing table sometimes you won't ping because the data plane is not established you've got the control plane good now this knowledge is very important for understanding all tunneling concepts like npls layer three vpn and so on so remember one thing that because i have root in my routing table it is not guaranteed that i will be able to reach those destruction i got the layer 3 roots through ospf for some layers rerouting protocol what about layer 2 what about the data plane if it's not formed if it is not in sync with layer 3 it will not be this is one example someone has got requested yes so aaron if let's say r3 right now it is in area 0 correct so no no no not r3 [Music] please focus on the topology we are not speaking about area 0. we are speaking about our one thinging 777 which is our seven here between these two okay between these two when r1 thinks 777 with the interface which is in area 3 the thing happens r1 let me show you in r1 when it is simply pinging without any source command the source ipheres of the packet will be the egress interface which is e00 thing happens okay because r7 knows about 10.18 network which is on e0 but when i source with lubeck 0 okay that is in different area which is in area 1 yes r7 has got no idea about area 1. so r7 cannot reply r7 will receive the packet but when it tries to reach one one one one there is no root you see where someone check show ip root there is no root for one one one one debug ip packets please pay attention now i'm going to ping one more time you see this guy will receive the packet look at this he receives the packet but he receives the packet from router one but when he when he's trying to root the packet back when he tries to respond back when he when he tries to reply back the routing table says i don't know i have one question here so type 3 let's say will go to everyone type 3 will be given only by abr what is type 3 route information of other area now one one one one is the route of area one right oh yes there is abn r1 no r1 is not abr only when you have area 0 it becomes an abr because this is there as the border between r3 and r1 it is not an abr okay okay i thought any router can be a abr no it needs to be a member of area 0 only area 0 can be a transit between two different areas you know without area 0 two different area can't share any update okay all right fine that's a good question that's why we are going to put the virtual link so let us now connect a virtual link between r1 and r3 i am going to put a wire between r1 and r3 but not physically then how do we put that wire to put the wire you need to know the router id of those two edge routers you are going to put a wire between r1 and r3 now what is the router id of r1 1.1 let's go and verify show ip ospf you should see okay one more thing i want to show you when i was typing this output i i got some thing to show you see it says i got a area one member i got an area 3 member nowhere it is mentioned abr do you see anywhere a b are mentioned nowhere in this output you see abr okay nowhere i see this is the route right he was talking about nowhere you see mentioning about avr but if i'll show you the same output on r3 see are one is in between area 3 and area 1 likewise r3 is in between area 1 and area 0 but you will see some difference there when you go to 803 then type the same comment show ip ospf all right this says i have area one and i have a backbone area connected as a result this becomes an abr is there any mentioning okay but anyway it shows that i'm connected to a backbone that is what it means abr but in one of the ios i've seen it will even show abr i was expecting that here all right yep so that is coming in the back bracket in this ios backbone backbone is mentioned which is not seen without backbone you cannot communicate between two areas so you need a backbone area let me try one more command show ip ospf interface you do not see the what sure if you protocol okay it's the difference in ios you know in some and i was in one of the hours i've seen oh here it is look at this it's an area border router this ios is very clear i didn't expect this clear i used to see abr keywords but here it is slightly different it is an area border router you don't see this one when you type on r1 let me show you on r1 r1 do you see this show ipo spf show ip protocol is the thumbnail you see the same ospf router you see nothing no mentioning about you see right below the default four the ospf stats and then below the router id you should see what it's an area about it you don't see that here you see even though it's a member of two different area it is not a area border router to to get that qualified ebr it needs to have membership with area 0. all right so i think i made thing clear if it's not clear please let me know let us talk more about it thank you right welcome let us now put the virtual link i told you you need to know the router id repeating again i'm emphasizing you need to know the route writing if you know this iprs of r3 you cannot form virtual link i know this router one night iprs standard 12 round zero not one i know the iphone's off router three it is standard 23.003 not enough to form virtually you need to know the you need to know the you need to know the router id of the two edge routers so the router id of r3 is 3333 let me show three you here three now this one is needed on r1 when you configure r1 you need to put this r3's route already how let me show you router ospf one have a close look please i'm saying virtual link sorry area one i'm not saying area three i'm not saying area three see you may be putting this virtual link for area 3 that's not necessary for a r1 to know r1 needs a connection to area 0 you put virtual link for area 3 or 30 or 333 that doesn't matter correct so you no need to keep area 3 in your mind when you configure a virtual link you want area 1 to be considered as a wire so you say area 1 i want it to be a virtual link okay this virtual link is from where r1 because i am right now configuring r1 till where till this route that's all that's all you go to r3 and do the opposite router ospf 1 area 1 is a virtual link till where till 1 1 1 1 that's all now you see a new neighbor comes r3 and r1 they are not directly connected even though they are not directly connected a new neighbor has come why you know there is a new wire called vl0 which runs ospf on it is how r3 can find a neighbor [Music] all right let's verify show ipo spf look at this it says full relationship because it it is a virtual link it will be like a point-to-point link so no dr media election and it's not a physical wire it's ospf virtual link you can type this command and say show ip route sorry show ip ospf interface virtual link it's okay i have another comment just simply type hit enter so you will see virtual link yeah i think i have to type this one to see show up your interface that's anyway it's not coming i'm getting this i simply hit enter uh it is a point to point link the virtual links are point to point link so the virtual link is a network type is virtual link type and the status point to point there is no drbdl relation all right so what is next there is no erpd reduction let's move on to r1 r1 i want to also see if someone is asking a question yeah i have just to make sure so virtual link read it on area one so virtually we configured on r1 and r3 telling that mr r1 you have area 1 member no that member direction via the direction you need to form a tunnel okay but area one has a backbone area right from r3 yeah area one has got a backbone area that is right correct so why don't r1 cannot perform the connection i mean r1 has the idea of the all this is going to backbone area right r1 r1 knows that i have r3 which is a backbone router because it is sending type 3 lsa yes i agree what you said is correct but r1 will also say that i have poor mr router eight you'll please locate where his road rate in third row voltage one will say i have this poor guy outraged i'm helpless you know i can't help him because i am not directly connected to area 0. i need a direct connection for for becoming an abr i need a direct connection i want to help him but i can't i know where is area 0 it is in router 3 but what is the quality to qualify myself as an ebr i need to have a connection okay aaron what if i have a physical interface as a router id on r1 let's say e0 come again please what if i have a router id on physical interface e 0 0 give that one keep that one as the virtual link id neighbor so that will be area 3 right that doesn't matter router id is just a name that router id can be a id which is not even in the router repeating again here i have given 3.3.3.3 as a router id because that is what used as a router id in r3 but to use as the router id i can even have some address which is not given in the router configured anywhere okay so that is not a reachable address that doesn't matter okay so my question is if i have a router id in area 3 what will be the configuration for the virtual link from area three is it area three virtual links see what do you mean you you're saying that instead of area one you have area three is it is that you are saying no no no no no no my question is the same area one sorry okay right now in this area route ride is one one one one but that is the loopback that is router ones router id and uh router 3 is not released yes so what if i have a router id on this side e 0 by 0 on area 3. it's ok ok let me do it for you because you're asking r1 please pay attention before that let us verify this and then i'll show what morally is asking so that you can see the same result only the route right is going to be different all right now you see after putting virtual link you can now ping from r1 with your low back previously when you are pinging from the loop you are not able to ping but now it will ping the reason is through virtual link r7 has learned about everyone you see it even knows router 6 which is an area to ping six or six or six third six with a source of seven seven seven if this thing happens what does it mean a router six also knows about this we are able to reach now i'm going to do whatever motley was asking i'm going to change the router id of r7 sorry r1 right now show ip protocol in ospf then outright use this i'm going to say router ospf 1 router id is i'm saying even the address which is not present also you can give but i'm just following whatever only give me i'm saying one and because it is already using another router id you have to clear so what i'll do is i'll say interface ethernet 0 1 shutdown interface ethernet 0 0 shutdown and then what i'll do is i'll clear the ospf process so that the new advertisement will go before that i'll go and clear clear ipo spf uh process an r2 as well as an r8 here ipospf process and now let's go to r1 and show ip protocol still it has not taken what i have given clear ipo spf process now show ipo spf sure ip protocol okay see this is the new router id new router id now i'm going to bring the interface up i have brought the interface up but the virtual link won't come up virtually link will start complaining why on r8 we have given one one one one as the virtual link address show ip ospf neighbor you will not have the neighborship via virtual link go to r3 and see r3 again you know it started throwing error it is because of the um virtually misconfiguration see virtual link is down okay now virtually so i have to change the address show run section router this i have to change after that the neighbor will come area one is a virtual link 10.18.0.1 now you will see the virtual look at this boom so area of the router doesn't matter router id it's just a name until let me change one more time interface ethernet 0 1 shutdown interface ethernet 0 0 shutdown i'm going to say router id something which is nowhere in this topology so router ospf 1 router id 123.123.123.123 fine and then clear ipo spf process and then i'll go to r2 and also all right so now again the virtual link will be broken uh let's bring it up okay before the let's verify show ip show ipos show ip protocol you see the new router id this is nowhere in our topology and now interface range ethernet 0 0 iphone one bring it up a new neighborship will be established between router eight and two after eight hundred two a new neighbor will come but the virtual link will not come see number two has come eight will also come come come come let's go to order two minutes it says i got a new neighbor called mr one two three one two three one two three on three like testing now r3 lost the neighbor via virtual link and i started getting the complaint again so what i should do i should again remove this area one is a virtual link one two three one two three one two three one two three now there is no more error has come up immediately so this address that you mention is just a router id to reach this router id the database will tell you need to go to 10.12.0.1 go and negotiate with the 10.0.12.1 and you get the tunnel up yes so i don't know right that is meaningless right in this design no way area three has got nothing to do with virtually area three is a poor guy he needs one abr he needs one area zero member for that only area one can provide something area one can show some mercy all right so then if we have one more different area below area please either see itself should not be here in first place it should be directly connected to the physical area 0 router this is a temporary solution this itself is not acceptable for long run so if you will have another area below below area three it will not work okay you you don't have any configuration to support that environment question never supports that okay just to make sure summary means real summary let me repeat again i want to remind you everyone somebody else just by name it is summary please remind our previous class video because it is originating from abr the summarization point avia is the summarization point if you will do summarization you will be doing well on abr so they have given a name a summary let's say unless you do summarization it will not be a summary let's say okay thank you welcome okay sorry i'm repeating again you can ask me doubt many times i have no problem i just told you that make sure that you know this very well if here is a summarization permit so it is somebody else all right

Channel: Jayachandran

Views: 213

Rating: 5 out of 5

Keywords: OSPF, ccna, ccnp, ccie, subnetting, networking, jayachandran, sathiyan, training, online, switching, stp, security, BGP, encor, nrs, nar, nokia, alcatel, lucent, sdp

Id: eY9td5yJQUQ

Length: 51min 17sec (3077 seconds)

Published: Fri Jul 09 2021