CCNP : understanding OSPF LSA types ( by sikandar CCIE(RS/SP) #35012 )

yeah so now in this video we will be discussing on OSP of a lesser types okay so that is the main topic so in the previous videos we have seen the OSP of design implementations using multiple areas OSP a virtual links and then the behavior of the OSP of in broadcast networks so now we're into the last part of the OSPF where we'll be discussing more in detail on a lesser types now in this video we'll be discussing on different let's say LS a stands for link state advertisement the meaning is its it's a normal ordered as mints which happens in OSP or process so there are multiple illicit types you can see the table here which defines LS a one two three four five six seven eight nine ten eleven so you got many types of Alice's so majorly we'll be discussing it on seven Alyssa's which are most common Alice's Nautilus is 6 because LS l 6 is multicast OSPF I will get into this individual Alice's whereas LSA eight nine ten level or generally very advanced Alice's where we can say LS 8 you used in external be external attributes in BGP and some LS n 9 10 level general we call them as opaque Alice's which are used in MPLS traffic engineering in some advanced implementations so we'll be discussing as per our CC and P we'll be discussing one of seven in essence so probably the main Alice's we can say the first file Isis of the main Alice's which are used so when you refer some documentation cisco dogs or any other Cisco press books when you find you will find a lot of theory covering these illicit types so so I am going to make a little bit simplification of these illicit types and we'll try to understand what is exactly élisa élisa is just an advertisement and we'll try to understand when and how these elicits occurs and how it happens okay so I got a simple diagram here so first we'll be starting with LS a one so I will be starting with a let's say 1 here the first type of ELISA I can simply say as LS a1 so a1 is a normal ELISA which happens within the area within the area means one router arousing to other louder within the area we call it as LS a1 so if we if you just take the diagram here so I got some diagram very simple diagram here I got three areas area 20 connecting to area 0 and connect into area 10 so I got three different areas this is one area area zero area 20 and area 10 and also I got some external routes external routes nothing but the routes which are learned from other than oh is pure protocol and they are getting redistributed into the OSPF so these are external dots these are we can say redistributed routes so we did some redistribution classes also so we know how to do a distribution between different routing protocols and the router which is doing redistribution we call it as autonomous system borders router so this is your ASB router which is redistributing the routes into into a OSPF and then these are your area border routers you can see ABR which are actually connecting multiple areas so here I got very simple diagram with three areas and the routes coming from eh-eh-eh are P or it can be our IP whatever the routing protocol okay so LS a1 is a normal advertisement sent by one internal router to another internal router so if I take an example here so this is the router this router is having some network called tend on inhalation assume that this is a network or tender network now this router is authorizing its own network to some other louder inside the same area so let's second example there is one more out were here so advertising to other router inside the same area so we call this as Allah say at the link stated Iseman nothing but the normal attachment but we call it as LS a1 which means any router informing to any other router within the area means the diamonds which car happening within the area we call that as LS a1 and generated by the internal outer one internal outer informing and update to another internal outer sending in a bit another internal lot so it can be any link it can be a point-to-point link or it can be HDL ceiling PPP link or HDL ceiling or it can be a SONET link whatever the type of connection you have in between the links so I got some notes very much in detail it says generated by the internal router they say one so it is going to - to absorber inside the area so it also includes some more information apart from network it also includes some network information as well as IP prefix and whatever the network type link type means it can be Ethernet or PPP hdl-c whatever the time so when utilizing the any network like a neural network it also advertises this information along with that update so it's floods within the area so it's floods within the area means this update will be sent only within the area it will not go outside the area which means so now this router is authorizing tend on it work to another router inside there so similar with this router arises to other router instantanium this router does this to other router so the advertisements whichever happens inside the area and only internal router is advertising to another internal router we call that as LS a1 okay and they say one is a normal advancement generated by the internal router one internal out or informing to another internal router ok so we call those masts LS a one ok so generally we can say Oh routes if you remember routing table or outs represents our outs coming from the same area which means whatever the road osment's happening inside the area and generated by any other in any internal router we call those paths or outs so output wise when you show IP route a wisp you will see them as a-rod's so they are flooded with in the area and they do not cross the area border router which means whatever the advertisement is happening inside there it can be any area it can be area 20 or it can be area 10 or it can be really row so any advancement happening within the area we call it as LS 7 so we can say this router arising to this router generally we can say it as LS a1 okay so similar way we got another ELISA ELISA - generally technically recorded as a network a lesson so dr informing to other router so if you remember in the previous sessions we discussed something called DRB dia elections in the broadcast networks so whenever you are connecting any network you have a routers connecting to a broadcast or bartender means each on its network so where there is a possibility of broadcast so whenever whenever you will see this type of networks like I got one network here router connecting to and Ethernet switch here and again it is connecting to some other routers so in case of broadcast networks that is something called dr media elections so DRB elections is actually a loop prevention mechanism so they will elect any one router as a dr designated router so if any router is having any update they have to send to the TR so he assumed this is a dr and assume this is your media media nothing but backup this internal okay so in this type of scenarios where you have a broadcast network and where there is a dr VD elections so assuming this is your dr designated router assuming this is your backup - no problem so there is an update so this router receives an update and it is going to inform that update to the dr so once the dr receives that update the job of the dr is to make sure that it sends to other routers inside the same network so it is going to inform to other routers inside the other routers generally we call it as LSA - unless you two is also same like LSA one it's a normal document generated by the internal router okay and generally read by the internal router it also referred as or routes so when you compare LSA one elicit two both are similar it's almost same except one difference the difference is when you have a dr BD elections in the broadcast networks it is sending the update to other router other than dr PDR this type of advertisement we call that as link state advertisement - LS a - so technically we call it as LS a - okay so that is a basic difference there's only difference so normal advancement normal iseman means if you are using a point-to-point link there is no dr BL if you're using HDFC there's no dr BD elections so there is only LSA one so when you have dr vidya elections and updates sent by the dr to other router we call it as a lizard okay so LSA one and ELISA 2 both are the updates are realize mints which are sent only within the area means whatever the heisman happening inside though is pure inside the same area can be LSA one or can be elicited so now coming to Alyssa 3 the third option now LSA one may have seen ELISA - also we have seen ELISA - also the same only difference is the dr sending the update to other the delivery called a solicitor so now we will talk about LSD 3 LSA 3 is something generated by the area border router now who will generate this advertisement area bought a router informing about the routes from one area to another area exchanging the route between the areas so now in general if you remember the process process is very simple in over sphere so whatever the advertisements happens like take an example here so now this router receives some updates it will send to this router this router every router will participate in the road as nodes so all the routers inside the same area exchange routes in the form of a let's say one or a lizard right that's what we discuss just now each router updates every other router inside the same area in the form of ELISA one ELISA to normal advancements now even the border order also will participate and receive the result from this routers all the routers from the same area now what is the job of this border router bottom router is a router which is connecting both the areas and this border router is responsible for exchanging the route between the two areas right that is the job of the border router so now border router is going to receive all the routes for our advancements from one area in the form of ls7 ELISA - and then it is going to send the same update from one area to another area and when it is sending the updates exchange route between two different areas we call those type of advertisements as ELISA three or dozens link's Jasmine tree I think technically we call as summary LSM so we called as summary elicit somebody let us say is you can see here this diagram will give some clear idea there is a aryabhata's router there is area one there is area zero in the area but a router is exchanging the routes between the two different areas so my diagram will give some more clear idea you can see this so this is the router which is responsible for exchanger or business so bottle outer you know we learned in the basic year who is process that water order is going to maintain the database of both the areas the border router is going to participate in the algorithm of both the areas and also border order is responsible for exchange the route between the two areas right now whatever is exchanging they generally we call those type of advertisements as illicit three ERA documents so the same case happens between this two it any two area so I am not specifically saying it is between between area zero and area 20 it can be between any two areas okay so now let's say one and lesser two harassments happens within the area and now they are exchanged with the different area in the form of velocity so next type of LSA we need to understand is LSF for the four type of Alice's so LSS is simple basic theory topic we need to understand it is little bit useful especially when you face interviews and technically you will be tested on these illicit types understanding so if you find documentation books you'll find them written in little bit more complicated with so but these are actually very simple just you need to understand that resonance so there is no much practical into it it's all about theory we need to understand now LS F 4 is also generated by the Aryabhata model so which means LS f 4 is generated by the idea what a router may sell as a fold will generate this messages but there is a difference between LS III and LS f for ELISA 3 is something which is exchange of the route between two different areas but LSA 4 is also an advertisement which is going to advertise the information about who is autonomous system border router so I'm just using my simple terms for understanding in simple Interop using technical terms Alessa 4 is going to advertise and saying that who is hanuman system bar chart so now if you remember we learned something called a SB ras vr is nothing but autonomous system borders router the router which is responsible for which is doing redistribution of external router external dots means it can be EHR P it can be our IP it can be BGP any other protocol other than the native protocol native protocol is OSPF here we are distributing them into the OSPF that router we call as a SBR router autonomous system water router so assume this autonomous system borders router name is name without ready we can say it's F it can be any name so let's say this is 11.1 not 1.1 assume that is the ID router ID of asbr so now this border router is going to inform to all the internal routers saying that the information is BR is f means the a ID or we can say is VR is lemon not 1.1 or own so the border router is going to advertise to all the internal orders how to reach external outs or who is autonomous system border router and who is actually doing redistribution of external routes into SPO ok so that's what this rail is safe forever - mentals NSA forever ties mints provides the information of autonomous system waters router so if we call it as summary élisa élisa 3 sorry let's say 4 is not some where a listen just a minute let me so in sir LS a 4 is used to read as the SBR information to all the other areas inside the rams atom system means nothing but inside all the whispure so they are actually generated by the ABR router and they are regenerated by the subsequent a BRS and flooded throughout the autonomous system number so which means so from this diagram we can see here I can explain you a little bit more better so you see the diagram here here as per this diagram you have some external routes external roads means the routes which are coming from our IP here GRP and this is your ASB router so SBR is advertising external routes to normal router normally is advertising to some other router here now once these routes are coming from here reaches the border router so in our example this is not the border router this is the internal router so it will not generate Alyssa for so these routes reaches the border router so this border daughter is going to arise to other routers saying that who is SB ras BR information this is your SBR and it is called LSA type 4 so every router which means it will address this information to all the routers inside the same area also it will orders to other side Badolato so now this border router is again rejecting the same message to other routers so it will go on to another area similar way it can go to other a july that whatever the number of areas you have it will subsequently move on or regenerated by every water route or inside the ATM so we call this as elisa for advertisements okay and then finally we have something out LS fi which is again LS fi is generated by autonomous system bottle order which means who will generate is Alyssa five messages Alyssa five messages are generated by autonomous system border router so this is the water out ESB a router so it will it is going to receive the routes and then redistribute them into the wispy of so generally whatever the routes or whatever the advertisements or whatever the messages relating to external routes getting redistributed into the OSPF we call them as lsfr so technically we call them as zoe one were you - if you remember we did in redistribution you want oh you two represents external routes if you remember we have seen four types routes or odd something but the routes coming from the same area if you remember the outputs when we did OSP of labs we will see different types of outputs like over outs Oh a routes and also we'll see Oh II won or a e2 so so the routes coming from the same area will be listed as oh oh rocks and when we when we see the routes coming from a different area different area means we are in area zero so if you are seeing the routes from area ten you will see them as a way around nothing but OSPF interlayer outs nothing but the routes coming from a different area and if you see something called you 100 a - so maybe when we did when we did remedies redistribution laps we try to we have seen this type of outputs so nothing but these generally we call them as external routes external nothing but the routes are learned from other protocol other than OSPF like r.i.p HRP but they are redistributed into the wispier okay so technically we call them as LSA one routes or Alisa - rocks technical names so anyone says LSA one Alissa two routes means you have to understand the routes from the same area and anyone say Alissa three routes you have to understand the routes coming from a different area so technically we call the math Alessi three routes and external routes are technically called as LSA Phi so LSF fire routes means you have to understand these are the routes coming from different routing protocol and getting redistributed into the OSP of so this is the final summary which i really suggest you to remember it's very simple you don't need to get into much detail on this thing because when you read some documentation you'll find much complicated languages technical terms used but this is a final summary what exactly Alissa defines pour outs from the same area oh I a rocks coming from treated from inter area routes nothing but from you from different area and lsfr represents so you don't have any LSA four types of routes so probably Alissa Phi you can see them so because Alissa for is not you don't see exactly routes it's actually information LSA for provides information about autonomous system water router okay so let me just quickly give some ID on LSS six which we which we don't use in general LSS six is not used because LSA six is actually used when you are using multicast routing then will be called as mos appear there is a routing protocol when we do multi casting there is a multicast routing protocols like teams parts more dense more protocols okay so it's beyond the scope of your CCNP routing switching silver's but just a basic idea so we call it as multicast ELISA which cisco routers doesn't support so cisco routers doesn't support this protocol so we don't use this protocol in cisco routers so the most commonly used protocols are PIMs past more dense mode protocol so we don't really get into this ls6 and also there is LSS 7 which is used in NSS a updates we'll be seeing in our next session relating to that LSS 7 so ELISA 8 9 10 11 these all obey callouses which are little bit more very advanced Ellis's used in advanced optimizations like MPLS traffic engineering in that options and some BGP implementations so as per our CC and P routing switching will be discussing the 7 Alice's in that 6 will we don't really use them so the 1 2 3 4 5 lessons we have discussed now probably 7 Alyssa I can't explain you right away without understanding this Tubbs concept so probably we will be discussing stops totally stops not so stops and then you will get some better understanding once we discuss those things then again I'll explain you that LS is 7 as well ok ok so router 1 it will say 1 2 let me quickly summarize all the Lissa's so Alyssa's so I will draw the diagram here I will explain you one more time quickly what exactly we need to remember regarding the Alice's ok so you can find some technical terms used in my document and also but that is good to know at the same time you should have a very simple understanding on different types of Alice's ok so unless a1 and ELISA - generally the ELISA switch are within the area which means one router realizing and update to another a turn router but as far as it is not going out so we call it as LSA one okay so one doctor informing or sending an update to another internet router so one router sending an update to another internal router we call it as LSA one okay so unless a to is an ELISA where you have dr BD a-- elections you know dr BD elections happens when you have broadcast networks and in that div elections when the dr receives an update and it is going to send the update to another into another router other than BRB do nothing but sending it to other routers we call this as illicit so in simple I can say illicit to happens when you have a broadcast or non broadcast networks where there is a possibility of DRV diem so LSA one I listen you can see LSA one ELISA - they are only within the area so they don't really go outside the area so in simple I can say LSA one into our generally over outs the routes within the area but now once this border routers receives all the information within the area it has to make sure that it sends outside the area nothing but it has to send to other ad also and that type of red asman we call it as LS 8 3 the link-state advertisements so which is technically output wise will see them as oh I a routes the routes coming from a different area so that outs exchange from different areas we call them as LS III routes or LS III update now LS F 4 is the information provided by the border router two other routers informing about the information who is a is BR his BR is f let's say let's give some name for a s BR it can be any name generally the router IDs are name so this is the information provided to all the other routers within the a s autonomous system means this is what we call as a transition a town system means the region where you are running the same common protocol so within my company we can say that's what we call as LS l 4 and l SF 5 he is technically we call them as external tops the routes getting redistributed into the OSPF we call them as LS f eyes and output wise you will see them as Oh Oh SP of fictional crowd type 1 external doubt type 2 so this type 1 type 2 also we have seen we are discussed in OSP of redistribution redistribution topic ok you

Channel: Sikandar Shaik

Views: 164,507

Rating: 4.649507 out of 5

Keywords: OSPF LSA

Id: Um3FeqL8vn0

Length: 25min 29sec (1529 seconds)

Published: Sat Aug 17 2013