1. ISIS Introduction – Level Types
So we’ll talk about the report’s introduction to the ISS in this section. So where we’ll see some basic features of issuance and then an overview of ISS, we’ll also see the metric calculation in ISS protocols and the different levels, like some areas, and finally we’ll see some addressing and how the addressing is done in ISS protocol. Okay, so let’s start with the ISS protocol. ISS is a protocol that is similar to OSPF, which has the same features, because both are link-state protocols that are going to maintain the link-state information of every route. So ISS was initially developed by OSI (Open Standard Interconnection), and because it is an OSI-based protocol, it initially worked with the material in the OSI protocol. Later on. This protocol has been modified to support your TCP and IP protocols. This means that the most recent ISIS protocol we use, known as integrated ISS, has been modified to support your IPV4 and IPV6 traffic. This means it will support your TCP/IP traffic as well, because we only use the TCP/IP protocol nowadays.
So ISS has been modified to support these features. So it was initially developed by Digital Equipment Corporation, which was standardised by ISO in 1992. So which is going to communicate between the networking devices defined by ISO? So it’s a link state protocol, classless, which is going to support your FLSM VLSM and all the similar features that we discussed in OSPF. It also uses the same algorithm that we use in the OSPF dexter algorithm for incremental trigger updates, and updates can be sent as a unicast or multicast. A metric is slightly different when you compare it with OSPF. We’ll see metric in the next class, and in the next set of slides, we have a metric also administered. The distance is 115 miles. Generally, ISS and OSPF are the two major protocols used inside the service portal network. They are primarily used because they are Linkstead protocols. They are going to maintain the linkage information for each and every possible role. So there are the main IGP protocols inside the service for the network. They are proprietors, they are standard protocols, and they are also going to maintain the links to information for each and every route. Okay? The advantage of ISS is that it is protocol-independent. It supports not only your TCP/IPX and AppleTalk protocols, but we mostly use TCP/IP here. So here the term “ISS” is going to refer to a router.
So you’re saying “ISS intermediate system to intermediate system communication” but we’re saying “router to router communication.” So how are we going to communicate from router to router? So ISS is going to stand for intermediate system to intermediate system routing exchange protocol. It was originally designed as a dynamic routing protocol for connection-less network protocols. That is one protocol inside your OSI. As a result, it was initially intended to run over the CLNP protocol. Now it has been a little bit modified to support your TCP IP also, but it was initially developed to support your CLNP protocol, which is an OSI-based protocol. We can say it’s a link-state protocol similar to your OSPF, and there are no major differences between them, but there are some similarities as well as some variations when we compare OSPF and ISS. So, as previously stated, the OSPF is now based on a modified ISS known as “dual ISS” or “integrated ISS.” So, initially, ISS was used as an OSI layer external gateway protocol; later, it was modified to support TCP/IP, which we call “integrated” or “dual” ISS.
So dual ISS works with the new features; it functions similarly to your standard IGP protocol, as well as the OSPF protocol, which will support much faster convergence when compared to OSP of the default hello parameters. It sends hello every 10 seconds, and the default daytimer is 30 seconds, so it will always send hello three times. So it’s a more stable protocol similar to OSPF that is going to efficiently utilise your bandwidth, memory, and CPU resources. So now the ISS protocol that we are going to discuss here is your integrated ISS, where we are going to run this ISS over our IPV6 protocols and also see how to run this protocol on IP Version 6 as well. The metric in ISS is the same; it’s a simple thing; it uses one link by default and the default metric of ten. Now in the case of OSPF, the metric will be calculated based on ten to four or eight divided by bandwidth. Whatever the bandwidth you have, it will be automatically calculated, and it is going to generate a value called cost. So, primarily in OSPF, the metric will be calculated based on the bandwidth. But in the case of the ISS, there are no bandwidth calculations, whatever the interface; each interface will be considered with a default metric of 10. It can be your faster than interface, orit can be your Seal interface or itcan be your gig Ethernet interface.
So whatever the speed of the link, the default metric will be 10 on every interface. If you want, we can even change it to any other number, but the default metric is faster than an interface, or it can be a sealed interface; whatever the speed of your link, it doesn’t make a difference. As a result, the default metric remains ten in this case. So the next thing we need to understand in the ISS is abortion levels. We have some border routers, just like in OSP; we have internal routers in a similar way; the ISS is defined in different levels, and we mostly have three different levels. We have level-one routers, which are similar to your internal routers inside the area. As a result, level 1 routers are also known as intra-area routing routers.
And we have level-two routers, which are considered your external routers and are responsible for exchanging routes between the two different areas. So we typically call them as a level two.And finally, we have the third category of routers. We have level-one and level-two routers that have both features, which means they can communicate with internal routers as well as external routers. So this is the basic difference we have in OSPF: we have some area zero, which is considered a backbone area. Here we have something called level two, which will be considered similar to your area zero. So we’ll come to these different areas in detail.
So before we get into this particular layer of hierarchy, the first thing we need to understand are the different types of routers we have in our ISS here. So, let us examine the differences between these various types in greater detail. The first thing we are starting with are level one routers. Level-one routers are the routers that will connect to the neighbouring network using only level-one routers or level-one and level-two routers. So it is more equivalent to your internal router. So it’s just like your stub. Also, we’ll see these things when we come to the lapse. By default, it will not allow routes coming from a different area. so different an area to get into that. It generally generates a default route. So this behaviour will be seen by default when we get into the labs here. So it is going to maintain the database only within the same area. We only keep the level one router database, just like we keep the level one routers. Okay? So by default, it is going to generate a default route. I’ll also show you the default. I’ll discuss these two points, the stop and the default root points, when we get into the lab.
Okay? So L1 should be continuous within the area, which means the L1 routers can only establish communication with other level 1 routers. Like here, I’ve got a diagram here. So I purchased a level-one router. And this level-one router will only exchange routes with another level-one router that is in the same area. Let’s take an example. This is one area, and in this area, level one routers exchange the routes only with level one routers, and level one routers also exchange the routes with another type, that is, level one and level two. Because this level one and level two are going to be supported, they will exchange routes with level one and level two. So these level-2 routers are actually exchanging routes with another router that is in a different area. Like here. In my example, this level-one router is communicating with the router that is outside the area as well as communicating with the router inside the area. As a result, your border routers will mostly be level 1 or level 2 routers that exchange routes between internal and external areas. So, when we talk about level-two routers, level-two routers, or the routers, these routers are typically in charge of exchanging routes between routers in different areas.
Like you can see, this router is in a different area, which is either area one or area two. Level 2 routers only exchange the route between the various areas. Suppose if you have a level two router, thislevel to router exchange or form the neighbour shipor exchange the route with only level two routers.And this level two router also exchanges routes with level one and level two because it is going to support level two also. However, because level-one routers are internal within the area, these level-two routers will not form a neighborship or exchange routes with them. So level one will exchange the routes. Level one, level one, and level two exchange the routes. But level one and level two routers will not exchange routes, and they will not form the neighborhood. Okay, so this is one thing we need to keep in mind. This level mismatch, in particular, is what we call a level mismatch if it occurs. In that case, they will not form a neighborship, and they will not exchange routes. Now, for the last type of router, we have something called level one or level two routers. And these routers are actually communicating with both the internal routers. So it is communicating with your internal router, which is communicating based on level one, and also communicating with your level two router, which is in a different area. You can see it is communicating with the other router on level two as well. So this router is going to maintain level one.
The level two router will keep both the level one and level two databases up to date. So it’s going to maintain two separate databases, which are a level one database and a level two database. And these are typically your border routers, like here, which are actually connecting to external routers that are in different areas and also connecting to internal routers. And these routes, these routers, are taking the route from the other area and then sending it to all the internal routers. And, by default, whenever you configure ISS, every router will behave normally. But if you want, it can changea specific router to level two.Or if you want, it can change a specific route to level one depending upon the requirement. Depending on the situation If my router is only communicating with internal routers, then I can change it to level 1. If my router is communicating with all the external routers and there is no internal router, In that case, we can use the level-two route. Level-two configurations, but they are not compulsory.
2. ISIS Adjacency – L1-L2
The next thing we need to understand is how our routers behave in different adjacency situations. As an example, I have a router that is level one and a router that is level one; both are in the same area. So they will automatically form a neighbour ship.
There won’t be any problem with them communicating. Okay? So this is very important to understand, especially when you are troubleshooting, because if you misconfigure these levels, in that case, it is going to affect your neighbourhood ship and also your exchange of routes. When troubleshooting ISS, the first step is to ensure that the routers are configured with appropriate levels so that they can exchange the route. So this will work because both routers are in the same area and are level 1. And if you take this example, both routers are at level 2. Level two in the same area also works because level two is similar to your backbone area, just like area zero. Levels 2 and 3 form the neighbourhood when designing within the area.
The neighborship is also formed by level one. But in this scenario, if you configure one router as level one and the other as level two, you can see that one router is configured as level one and the other as level two. They will not form a neighbouring relationship in this scenario. Why? because there is a mismatch of levels here. So this is not going to work. And whenever you see this type of scenario where both the routers are in the same area but they are not forming a neighbour relationship, there is definitely a mismatch of levels here. So we’ll see in detail in the next slide how we need to identify whether they are in the same area or a different area. So first let us figure out which particular configurations or levels—the different types of levels—match and which levels do not match here. For example, if you configure levels two and one, level two, this will work because they are in the same area. Okay, same area. Level two works because here we are using level one and level two, which means it supports level one as well as level two. So they both exchange the routes based on level-two information. Then, in the following diagram, if both routers are level 1 and the other router is level 1, the neighborhood is still formed using level 1 information. So level one and level two are types that are going to support all the different levels.
It will communicate with both levels one and two. And also, it will communicate at level 1. Level two raptors So it will communicate with every type of level rafter in general in ISS, and this scenario also works as if you have a level one, level two, level one, level two neighborhood, which is by default. So, with the exception of this scenario, all of the remaining options will work and will form the neighborhood. So the next thing, we have some other combinations here likehere also I got some few combinations like you can see,I got one router in level one and other roles inlevel one but they are in different areas.In that case, they will not form the neighborhood. Because the router must be either level two or level one in order to extend the route between the two different areas. So far, this scenario is not going to work. So in a similar way, if both the routers are in different areas here and here, in this case, this is going to work because both the routers are in different areas, and to extend the routes between different areas, it must be either level two or level one. Level two so this is going to work.
This is not going to work here. In a similar way, here also, if your router is at level one and level two, meaning level one is not going to exchange routes with different areas, it will not work. In a similar way, this is also not going to work; in fact, here, this will not work because level one will only exchange routes with routers within the same area. So it’s not going to work here as well.And in a similar way, level one will not work for different areas. Simple thing: level one will not work for the exchange of routes in different areas, and level two will not work for the exchange of routes in the same areas. So in a similar way, this is going to work here. So these are some of the combinations of different levels. We need to understand this so that we can easily design the ISS networks here. So, let’s look at some sample diagrams to get a better idea of what levels should be present. Now here are some simple diagram samples showing which routers must be level one and level two. Like here, you can see this border router, which is actually communicating with internal routers; here, it is also communicating with external routers. So now this router must be configured as level 1. Level two. Assume you change this router to level two instead of level one so we can even out the levels: If I change this router to level two instead of level one, it will be able to exchange routes with these two bordering other area routers.
But it will affect the exchange of routes with the internal routers. So in this scenario, this router must be configured as level 1. It must be level 1. And, once again, because it exchanges routes with both internal and external routers, this router must be level one or level two. Similarly, if you take the example of this router, it is also communicating with internal external routers, which is level two, and it is also exchanging routes with level one. So it must be level one, level two.Now, the three routers I mentioned earlier must be configured as levels one and two; if you change them to level one, they will not exchange rods with other routers in different areas. And if you change them to level two, it is also not going to work because it will affect the communication exchange of the routes or the neighborship between the routers inside the areas. So it must be conference level one or level two; that is mandatory. So in a similar way, if I take one more example here, this router, you can see this area as having three routers. As a result, this router can be configured at level two or level one or level two. Why? Because this router is only exchanging routes with other routers that are in different areas, So there is no internal router connecting to this router. So in this type of scenario, you can use this router as level two or it can be level one or level two; it’s up to you. But in this type of scenario, it’s recommended to use just level 2 because we’ll minimise the size of the database by just maintaining this router and only maintaining level 2 databases.
However, the other routers that I discussed must be level one, level two, and similarly, if itry to see some specific routers like this router here, I can now configure this router as level one. Why? because it is only exchanging routes or communicating with the other routers that are in the same area. So now we can change this to level one. But I cannot change this to level one because if I change this to level one, it will affect my communication with the other routers in a different area. Okay, so now you need to figure out which routers work with Level 1, which work with Level 2, and which routers we should use. Level one, level two Now that I have this router, I can set it to level one. It is going to work because it is exchanging routes only with routers within the same area. So it can be level one, level two, or I can even change to level one. Also, it is going to work. So depending upon the scenario So this simple design, this diagram, is going to give you some more clarity on understanding the different levels—when we should use level one, when we should use level two, and when we should use level one, level two, and we can even change the levels. We’ll see that when we come to the labs. Okay, now I’ll try to take one more scenario here. As you can see, this is one more design that is slightly different when compared with the previous one. Now, this scenario is also valid, because in OSPO, we have some area zero. like we have an area zero router that is communicating with area one, area two, area three, and area four.
So whenever you want to connect area one to area two, you have to go via area zero. So this is the default design in OSPF. In the same way, we can do the same thing in ISS. However, there is no specific area zero on the ISS. So we need to maintain contagious routers with area zero. So if you’re maintaining all the routers at level 2 in this scenario, it’s going to work because level 2 routers are going to generally be considered your backbone routers or backbone area, which is similar to area 0. Now whenever you want to exchange theroutes between different areas then we needto configure the contiguous this middle area.The transit area must be designated as level two. So when you do that, it will allow you to exchange the routes between the different areas because level two will allow it to happen. You can connect any non-backbone area to any other area via this backbone area. As a result, two will be considered your backbone region. We usually refer to it as a level two. So in a similar way, like we have Area 0, which will be considered your backbone area, So here, level two will be considered the backbone, whereas all the level one areas will typically be considered the non-backbone, or normal, areas. We can say similar things about OSPF. This is a slight change in the terminology when we compare it with OSPF.
3. NSAP Addressing
So in this video, we’re going to continue with the basic ISS. Now here we are going to understand the addressing how it is done in ISS. Now, typically, we don’t use normal addressing like we do in OSP. For ISS, we don’t use a normal IPV, so we still use a normal IPV for IPV six addresses, but the ISS must be configured with something called an NSAP address. We call it a network service access point address. We need to configure this address in order for any specific device, especially the routers, to be identified in our routing process.
But when you get into the inside of your OSI, we have something called AFI ID and then DSP values, which are collectively referred to as your area address, and then we have some System ID and N selector addresses. So let’s try to understand these valueshere what exactly these values defines.So an NSAP address consists of different fields, like the first field we called the AFI field. So AFI is a value that will define that it is an authority format identifier, a one-byte value that will provide the structure and contents of the various fields available this year. So these values will tell you what content is contained within this address. In this case, the authority identifier is always set to 49. In general, when we are assigning the addresses, we generally use this AFI value, which will be set to either 47 or 49, which is going to be for private purposes. So that means whenever you are assigning the NSAP address when we are defining inside the ISS, we use 49 in the first portion, which means it looks something like this. So the address always starts with 49 here. So something called “49 dots” is OK? So we call that a 5-value. And then there’s the address format, which is the next thing we have here. I wrote 49 here, which is going to define this address as one we are going to use for private purposes. And then in this againyou got some different addresses.This portion is going to represent your system ID, as you can see here. System ID is just like your device host address—you know it is going to identify a specific device in the network, especially here where we are going to identify a specific router. So System ID is going to identify a specific device, and it is in three portions. You can see there are three portions here. It must be in three portions, as you can see, and I have three portions here. Most likely, it is a 48-bit address. We can say it must be a48 bit address written in three portions.Each portion is going to represent 16 bits. Now it’s up to you.
You can write any address in Hexadecimal, whatever the addressyou want, you can decide any address, but make surethat this address must be unique in your network.So just like your host IP address, it must be unique. So this particular six bytes—we can say six bytes or we can say 48—has a 48-bit address that is going to represent your system ID, which identifies a specific device. Now, the next thing we have here is this part. This is going to represent your area ID. Now, if this number is the same, let’s say I have two devices. One device is using one as an area ID, as is one router, and the other router is also using the same area ID. The system ID must be unique; it must be different everywhere. Now, these two routers will be considered as they are in the same area. So we probably refer to them as the same area because the areas of this router and this router match here. So now, for this number, there is no specific length for this.You have the option of writing 16 or 32 bits. You can write 48 bits. So there is no specific length. Mandatory: You should use it, but the system ID must be 48 bits. And these numbers represent your AV ID, and 49 actually represents that you’re using them for private purposes. So it must be either 47, 49, which arestandard numbers which are going to be used.And the final part you see here will be your NSN address.
We call this a “N” selector address, which will always be zeros. So we don’t write anything. As a result, if it’s separated by dots, it’ll always be zero. So when we are writing “always zero,” it is going to represent that we are implementing routing, which means zero means nothing, but there is no transport layer information carried and it is used for routing, for ISS here. So, let’s take a look at this. I wrote some things here, and you can see this is what I said just now. The N-factor address, which we call the “net address,” will always be set to zero. And, of the entire address, whatever we’re writing, 490, one will represent your area ID, and the remaining numbers will represent your system ID. And then finally, this is your NSELECTOR address. This combined address we call the “Net address” or “network entity title.” So it is referred to as network entity title address, where we always use N selector address, which is always zero. It’s a common practise where we keep it all at zero. Now, the Net address implies the routing layer for ISS itself. ISS is nothing more than a router for a router, with no transport layer information. which means that’s what this zero represents. now Finally, if we summarise here, we got the AFI address, which is going to be used as 49 dots, which is going to define it for private use. And then we are going to use Area ID. Area ID will be the next, and it should be at least one byte minimum. Depending on the requirements, you may write more.
The system ID identifies your final system. The N system represents the intermediate system of your computer, and the R system represents your routers. Okay, so in general, it will be six octaves; it must be 48 bits, which will be identified as System ID, which means I’m going to use System ID as one. It can be any number written in hexadecimal. And finally, the last number, which we discussed here, is what we call a nselector address, or NSAP selector NSEL address.
It will be always set to zero forISS when you’re implementing on the routers.So this is generally how the addressing is done. So, whenever you want to configure ISS, or run ISS on a specific router, we must enable this address with a command called net inside the router mode. Then we had to type the NSAPaddress, or the full address, or whatever you chose. And then we need to tell like this, okay?So in this, as I said, this particular six bytes isgoing to represent your System ID which must be unique.And this portion, whatever the portion means, must be at least one byte or eight bits. You are allowed to write more than that; it represents your area ID. And this is your AFI address, which will always be set to 49, which defines your private address. And your NSAP selector address will always be zero. So when you define this address, then we can understand that the router is enabled with ISS. So now the router will be identified in the network with this network address, or net address. And after that, we need to enable some commands under the interface to advertise. But this is something that is mandatory for you to do to enable ISS on any specific router.
So now let’s try to understand some addressing examples here, like the ones I put here where it is going to define the routers in the same area or a different area. For example, I have all of these routers in the same location. So I’m going to use System ID as 4, 4, 4 for this router, a specific router, and 3, 3, 3 for another router. And for this router, it’s not written here, but I’m going to use it as 490 zero, two, and then I’m going to use 222-22-2222 some zero zero. And if you see one thing common among these three routers, you have the same area ID. Now, based on this number, we can identify whether the routers are in the same area or a different area. So when you see this number is not the same, in that case, you have to understand they’re in different areas. And if you notice that these numbers match and are the same, we call them being in the same areas. Obviously, the system ID must now be unique. And in a similar way, if I take this example here, I’m musing on 490 0 1 as my area ID for these routers, and you can see the system ID is different here, okay? Similarly, if I use this example, the correct answer is five five five. Because the system ID must be unique, I believe it displays five. And here, these two routers are in the same area, but the area ID is 0004, and this router is in a different area using the area ID of 3. So, based on the areas, we can easily distinguish whether they are in the same or a different area by looking at this portion. Now we need to define the levels. Also, if you remember, we discussed the different levels. Now if I configure this router as level 1, it is going to work.
One thing to remember is that level one is the default level and it works with all router types. This means it will communicate with both internal and external routers. But it’s recommended to specifically define the routers as either level one or level two, or level one and level two, depending upon the requirement. So as of now I can use this router, I cannot usethis router as level two because if I make this router aslevel one, in that case these two will not communicate.So we need to ensure that either I need to change it to level one, or if I change to level one, it will not communicate on this side. So what is the condition here? I had to use it as level one and level two because it will exchange, forming a neighbour shift with both an internal and external router. In a similar way, if I take this router, it must be level one or level two, and in a similar way, if I take this router, we can make it level two only because it does not have any routers outside the area. And if I take this router, it must be confident at level one, confessed at level two, and only level one can be configured. And I can only configure this router as a level 1 device. So this is going to work, okay? Or you can make all these routers part of level two. So now either you can do it like this or there is one more slight change we can make: we can make all these routers Level 2 devices, just all routers. If you make this a level two area, it becomes a backbone area just like area zero. It’s not Area Zero here. We don’t write in area format like we do in OSPF, but it will become a backbone area. And now I can exchange the router from this area, which you can see here. I can now set this router to level one, level two, level three, and now level two. So this is also one simple scenario that is going to work, which you can try. So, when you have multiple areas, such as you have going through, you must ensure that any one area acts as a backbone area or transit area, just as the OSP of Area Zero does.
So this is something basic we need to understand. And once we understand the addressing, the first thing we need to understand are the levels, and the next thing we need to understand is how they will be identified as being in the same area. If this number matches, we consider the same area; if it doesn’t match, it will be considered a different area. So understanding the NSAP address means understanding these two basic things before we get into the labs. Because when we are conferring the ISS on any specific routes, the first thing we need to do is define the NSAperters, and then once we define them, we need to ensure that the level type should be the same for all. As a result, we must adjust the levels based on the situation. This is especially true when troubleshooting. So these levels are an important thing to check because if you misconfigure the levels, you may encounter errors such as not seeing neighbours or exchanging routes. The first thing we need to do is check the NSAP address; that’s the first thing. And the next thing we need to check is the level types—whether they are according to the scenario or not.
4. ISIS Configuration – IPv4 – IPv6
So now once you understand the different level types, the first thing we have seen, if you remember, is that we tried to understand the basics. The first thing we need to understand is the addressing part, how to configure the addressing inside the INSEPaddress, and the next thing is understanding the different levels. So because we are configuring them in multiple areas, we need to ensure that different levels are correct in order to have a proper exchange of other routes. So now that you understand this, we’re ready to start our labs, and we’ll see some basic configuration commands. So if you want to configure ISS on any specific router, the first thing we need to do is configure ISS with this command. So we need to go to configuration mode, and then we need to say router ISS. And there’s something called process ID in most of the new iOS. You can even define a process ID similar to OSPF here. So you can run multiple instances of ISS, each with its own name or number.
There is no specific number range here. So you can use any name. So most of the time in your recent configurations, you may be using the process ID name. So, in my lab, I’m not using process ID; I’m just using a regular router ISS, which is a default process, but you can use multiple ISS processes running on the same router, similar to your OSPF. So once we configure the first command, which is the router ISS, So this command will enable the protocol, and once in router mode, we need to configure the network net address, the network entity title address, which, remember, must begin with 47. 49 AFIaddress and will be defined as a private purpose. Then we need to define the area, which can be whatever you want. And then we need to define the system ID—any number, it’s up to you, you can use it. I just make it simple like this, and then we finally need to tell Nselector’s address, which must always be zero. So this address must be defined inside the router mode with a command called net. So it is going to start with “net,” and then we need to type the address. And once you enable this, your ISS starts working. These are the bare minimum of commands that must be added to the router mode. And there is no network command once you do this to advertise any interface, say I have a land interface and I want to advise this interface. Instead of a network command, we just need to go to the interface, and under the interface, we need to give the command called IP router ISS. If you want to die as your IPV-4 address and also use IPV-6, we must use the IPV-6 router ISS command. So, depending on the situation, when you enable these two commands, you can also enable V-6, which we’ll be doing in our labs. So in this lab, we are going to run ISS for both IPV4 and IPV6, and then we are going to do some troubleshooting on that and some additional configurations as per the requirement.
So we are not doing it separately. We are running both IPV-4 and IPX at the same time, but only the ISS will be used for both IPV-4 and IPV-6. Unlike your OSPF, if you know OSPF, we have two different versions. We have OSP of V2 for IP version 4, and OSP of V3 for IP version 6. However, when it comes to ISS, the same ISS net address, or common ISS, can be used for both IPV-4 and IPV-6. So the neighborship table, the database table, everything is common for both, but if you want, we can make the shortest path algorithm, the SPF algorithm, also common for both. We can even change it to separate if you want by using some advanced multitopology options. We’ll get into those things in future classes. But as of now, the ISS is something common for both IP version 4 and IP version 6. So these are the minimum configurations we require if you want to run ISS on your specific routers. So we are ready to start our lab here. So, in this lab, I’m going to use several routers. You can see I have six routers here. So now I’m going to read the task here. The task is to set up ISS for both IP versions 4 and 6. So I’ve got three router sets here, like three router sets here, three router sets here, and three router sets here. I’m going to configure these three routers in one area and the remaining three routers in a different area. And finally, after that, we are going to exchange the route between the different areas. And then also in the next task, we’ll be adding some more, some additional advanced commands, optimization commands, and we are also going to verify them as well. So this will be a major task in our lab here. So first, we’ll be starting with the task here. You can see that the first task is to ensure that your routers, router one, router three, and router four, are all in the same area, and the area ID should be 40-913, which can be any number.
So I’m going to use router one here, router three, and router four here, as you can see. So these are the default routers I have, so I’m going to use them in a single area. So first thing I am going to see how to configurethe routers in the same area and after that we’ll bemoving on different areas also and the system ID must beconfigured with some address like area ID is this and thesystem ID must be zero, zero zero, all zeros and finallyyou have to say X so X represents router number soin order to make sure that it is unique on therouter one I’ll use one and on the router three I’lluse three and on the router four I’ll use four systemID must be unique so I’m going to use all zerosn one as system ID and the N selected address isall zeros so where X is your router numbers covering router134 and I’m going to advertise all the loopback interfaces soall my interfaces are preconfered with IP addressing like all theother sync in my diagram series I’m using ten dot zeroXY x so X represents suppose this is the link, thisis router three, router four or router three router one soit will be like ten 00:13 so if it is routerthree so I’m going to use router one, two, three link,I’m going to use it as ten 00:13 three if itis router one I’m going to use 1013 one like thisand all the connected interfaces I’m using the similar type ofaddressing and each and every router interface having one loop backinterface which I’m using for testing so it is actually preconfigured with addresses like in case of router one it isone one there is a default address with 32 subnet mask and on the router two, I’m using two; similarly, on the router three, I’m using three; like that, these are low-back addresses that I’m using for testing purposes, so this is the default topology that I’m using in my labs. So, for the most part, this topology is designed for my CCI service for classes, which is a service for the core network, which is running six routers with multiple links, so we are connecting router one router, so we are going to use a similar topology, it’s the same topology that we are using for implementing and testing over ISS. Also, we’ll configure these three routers in one area, 491-0134, and these three routers in the 49 00:25:06 area, and then we’ll see how to exchange routes between these areas. So, before we start our lab, I want you to have some basic ideas on I processing, as well as some basic knowledge of the connected interfaces that will be using them, starting with ten dot zero dot XY dot x with a slash 24 subnet. It will be one. One. If I’m using Router 2, it will be like that. So I’m using loopback interfaces. I don’t have any LAN interface, so I just want to test loop-back zero to loop-back zero testing, assuming that it’s my LAN interface. So we need to ensure that our low-back channels ping each other based on that. So, I don’t need low-back one or low-back two in this lapse, but perhaps in advance, for the classes, we could use these specific loopbacks in the future. Following that, the default IPV-6 addressing, which will be similar to that one, will be 2001.
All addresses begin with and I’m going to use XY. For example, if I connect router one to router three, the result will be 2001 with 13 colons and colon X. So in the case of router 1, it will be one; in the case of router 3, it will be three. So this is the default addressing I’m using for connected interfaces. And for my loopback interfaces, I’m using 2001 colon colonxx.I think I’m using this address, which you can see has a slash value of 128, the default, for the loop back. So in case of router one, I’m using theloop bag zero addresses, 2001 colon, colon one.It is two, three, and four in the case of Router 2. Like that, it will go on. So these are the default configurations, which I already have preconfigured in my topology and am using here. So if you want, you can just refer to these addresses. I documented some addresses here. You can even use this for the address part. You can refer to them for your basic IP addressing and IPV6 addressing configurations. So this part is already done. So I’m not getting into basic IP addressing and IPV6 addressing. So I’m ready to directly get into our lab, where we’re going to configure specific routers in a specific area. So as per our task, here is what we discussed just now. Our task is to configure these three routers. Router one, router three, and router four are in area 490139 00:13, using ISS for IP versions 4 and 6. Okay?
5. ISIS Configuration – IPv4 – IPv6 – LAB
So let’s get started with our lab here. So, first and foremost, I’ll begin with router one. So, router one, if you see the first thing I’ll do is verify my IP address, they’re already set up. So I just tried to verify my IP address. It is the same or not for connecting one and two by zero by zero. I’m using twelve and S one by zero to connect one and three, one three and S one by one to connect one and 414. Finally, there’s the loopback interface, which I’m using. So similar way, if I go to my other routers, whichis my router three and router four swipe interface brief.
So these are the default addressing which I’m using.In a similar way, if you want, you can even verify IPV six addresses, which are again preconfigured here. So they are mostly preconfigured in case they aren’t forming the neighbour ship; perhaps there is an IP address misconfiguration, which we can easily troubleshoot. But hopefully there are no errors here. So all the routers are preconfigured with the exact IP addressing scheme. What you will see over there is some extra addressing, which I will also be using in my advanced MPLS classes. But these addresses are preconfigured here, even the low back. You can also see it here. So let’s get started with our basic configurations. On router one, I’ll start with this one here.So the first thing we need to do is configure outer ISS inside my router mode, and you can define the processID here, similar to an area tag, and we can use it. I’m not using it here, so I’m just leaving it blank with the default process ID here. And then we need to define the network address and the network entity title address. It must be as per the question. As per the question, we are using 49.34 as your area ID. And then we are going to define the systemID as being all zeros and 10 zeros. so exact area ID. So it’s not necessary to use all zeros; you can also use all ones; it’s entirely up to you. But it must be unique. So I’m just using it the same way. So once we define the network ID, the next thing we need to do is enable the interfaces with IPV6 and IPV4 router ISS commands. So, as per our diagram, if you see here in my diagram, I’m using this interface, these two interfaces, and then I’m using the lowbag zero interface—three interfaces I’m using. Still, we have not come to this interface, so we’ll see that in the later tasks. So I’m connecting to my router three by entering my interface one by zero. I’m going to say IP router ISS commands to enable IPV 4 ISS and then IPV 6 router ISS commands. Similarly, I’ll enable it on another interface, IP router ISS, and IPV six router ISS, and then on the loopback interface, IProuter ISS, and IPV six router ISS. So, if I want to verify, we’ll verify the neighbour ship after we add this command. The next step is to configure the same commands on routers two and three. So, if we just look at the history commands, I can go straight to routers and configure. If you can only use Notepad to modify these commands, it’s up to you to save your time, but if this is the first time, I suggest you configure all the commands so that you have enough practice. So 0134 is an area ID, and then all zeros, and router3 is three, and the next set of addresses is zero. And then I’m going to my router number three.
On the router three, I have two interfaces, one by zero, which connects to my router one, and the other by zero, which connects to my router four. As a result, the IP router ISS command and the IPV6 router ISS command In addition, we are recommending our loopback interface so that we can test connectivity between all of the routers. Instead of using a LAN interface, we are using loopback to achieve loopback reachability. Done. So now, in a similar way, we need to do the same thing on the router 4 as well. So let’s go to router four router ISS network ID 4934 because I want them to be in the same area.So the area system ID is all zeros, and then finally, the router number is 4. After that, interface, interface. On the router four, I’m connecting interfaces zero by zero, which is connecting between routers three and four. Similarly, I’m connecting each interface between one and four one by one. So IP router ISS, IPV6 router ISS, and IP router ISS commands And finally, on the loopback interface also, I need to enable the same IPV6 router ISS to enable the So once we did this, we completed the initial configurations as per the requirement. We configured all the routers as per our diagram.
You can see all the routers. You can find the steps here. In a similar way, we just configure every router. similar way on the router 3 also, and we did the same thing on the router 4 also. After that, the next step is to confirm the neighborship and ensure that it will be established. So, to confirm the neighborship, I can use either the “show ISS neighbors” or the “show CNS neighbors” commands. So I prefer to use ISS neighbors, and then after that, we’ll verify the database, and then we’ll do some basic verifications as well. Let us try to go to router 1. So to verify, I should see the neighbour ship show ISS neighbours you can see; I can see routers three and four are my neighbors, and by default the routers are running level one and level two, so the default type is level one and level two, and through which interface I’m connecting, and the state is up. Now, in a similar way, if you want, you can even use “Show CLNS neighbors.” Also, it’s going to define the same thing, but with a slight variation in the outputs.
After that, if I try to check the database with show ISSdatabase, you can see these routers are by default running levels one and two, so they are going to maintain the database for level one as well as the level two database. So it’s a router’s default behaviour because we didn’t assign any level type to our routers. When you don’t confirm any level types, it runs by default as level one and level two, which means it is going to maintain the default database of level one and level two. So in a similar way, if I try to check on other routers, like routers 3 and 4, for any one router, I’m getting into router 3. Show ISS neighbors I can see the neighbouring ships on router three; I only have one neighbor, router one, and I can see router four as a neighbor. But now there’s a slight difference in the output here. If you try to see here, the difference is here. By default, you form a neighborship with your point-to-point interfaces. So by default, you have only one neighbour for both. But when you’re forming the neighborship with broadcast networks like Ethernet or faster interfaces, you have a separate neighborship for level one and a separate neighbourhood for level two. So that’s what you’ll see here. For router 4, it is showing me two neighbors, two different neighbors: one for level one and one for level two. So don’t get confused here. So it’s actually the same router, but it is differentiating the neighbours with level one and level two because both routers are running level one and level two. So that’s the default behaviour here.
The same thing I listed here By default, all the routers are level one or level two. So each router maintains a separate database forlevel one, level two, and in case ofEthernet broadcast networks, ISS maintains a separate neighborsfor level one and level two.The next part is verifying the routes. I should be able to see the routes for IP version 4 as well as be able to ping, and I should be able to see the routes for IP version 6 as well, and I should be able to ping between these three routers. That’s our next step to verify. So let’s go to router 1. On router 1, I should be able to see the routes coming from three and four. As you can see, because they are in the same area, I can see the route from level one. So I’ll get the routes in the form of level 1, and I can see the routes coming from routers three and four. And in fact, I can also ping them. If you want to ping from the source for testing, or ping from loopback to loopback, you can use the source address. Okay. For testing. And I can even say “four four.” I can ping them in a similar way if I try to verify my IPV6 routing table. As you can see, no IPV6 routes are coming here. Now, any specific reason? Here’s a simple thing: we enabled IPV6 unicast routing here. There’s a reason for this: IPV6 routing is not enabled by default in all iOS routers. So please enable IPV-6 unicast routing and allow me to do the same on router 3.
IPV has six unique identifiers. So, now that I’ve enabled this, let’s give it some time to settle, okay? So I was trying to check with OSPF, weare not running OSPF, we are running ISS.So we should be able to see IPV6 over Route ISS now. I can see the routes coming from router three, and I can see the routes coming from router four as well. And if you want, you can try to ping those IPV-6 addresses on the router 3 with source interface lowbackzero; you can see it’s pinging as well as when I try to ping router 4 as well. It should be pinging. So now there is no separate neighbourhood for IPV. For IPV6, you have a common neighbourhood for ISS by default. So we don’t have separate neighborship commands for ISS. So the only thing we need to check is your route exchange for IPV4 and IPV6. If your IPV4 is correctly configured, you’ll see that IPV4 routes will be coming, and if you enable and configure IPV6 properly, then you will be able to see your IPV6 routes also coming into our routing table. So this is a very basic lab that we performed here, where we ran a standard basic ISS with a single area. So now, probably in our next sections, we’ll be getting into much more detail, like some basic optimal, like understanding some other options relating to our ISP.