Welcome back to the Cisco Introduction to Networks lecture series. Today we will be covering Module 12, IPv6 Addressing. If you would like to learn about the previous modules, I will leave a link for the playlist in the description and you can go ahead and watch those lectures.
In this lecture, we will cover IPv4 related issues, Hence why we came up with the IPv6 addressing scheme, the IPv6 address representation, the IPv6 address types, GUA and LLS static configuration, dynamic addressing for IPv6 GUAs, the dynamic addressing for IPv6 LLS, IPv6 multicast addresses, and the subnet and IPv6 network. IPv4 issues. IPv4 is running out of addresses. I have mentioned this previously on my previous lectures.
Unlike IPv6, the IPv4 addresses are limited in number of addresses we can issue. So the IPv6 is the successor to the IPv4. IPv6 has a much larger 128-bit address space.
The development of IPv6 included fixes for the IPv4 limitations and some other enhancements. With an increasing internet population, a limited IPv4 address space, the issues with network address translation, and the IoT devices the time has come to transition into ipv6. As I mentioned before the ipv4 is pretty much been exhausted and we have been using NAT as a temporary solution for keep going with the ipv4 addresses.
Remember I have described what NAT stands for, network address translation and what it does with ipv4 by separating the private ipv4 addresses from the public ipv4 addresses and one of the reason why we went with that overhead is because we literally ran out of ipv4 global addresses and the solution right now is to go with the ipv6 addressing scheme with 128-bit address space on the right hand side of this screen you will see the ipv4 exhaustion In other words, that we are running out of the IPv4s like in North America, we are running out around July 2015. And in South America, we are running out in April 2011. And in Europe, we are running out in September 2012 and so on and so forth. We are literally running out of the number of IP addresses we can give out in the IPv4 space. And that's why we came up with IPv6 scheme. IPv4 and IPv6 coexistence. Both IPv4 and IPv6 will coexist in the near future and the transition will take several years.
I would say transition would take several decades like it probably gonna take one two or three decades probably to completely move on to IPv6 addressing schemes. The IETF has created various protocols and tools to help network administrators migrate their network to ipv6 these migration techniques can be divided into three categories they are dual stack tunneling and translation dual stack the devices run both ipv4 and ipv6 stacks simultaneously this is the most common category that you're going to see in your network administration carrier especially in 2022 you because we are still in the phase of transitioning and then tunneling is a method of transporting ipv6 packets over ipv4 network the ipv6 packet is encapsulated inside an ipv4 packet this is also something that you may see in your field work translation is the network address translation 64 which is the nat64 that allows IPv6 enabled devices to communicate with IPv4 enabled devices using a translation technique similar to NAT that we have for IPv4. Remember in IPv4 the reason why we came up with the NAT is because we are running out of public IPv4 addresses so we need the network address translation between the public and the private IP addresses.
And the NAT64 is actually used not because we are running out of IPv6 addresses but because we are using that NAT64 to communicate between the IPv4 devices and IPv6 devices. This is an important concept for your exam so just remember that. Note that the tunneling and translations are for transitioning to native IPv6 and should only be used where it is needed. So, dual stack you will see a lot, tunneling and translation you see only where it's only needed.
The goal should be at the end to use native IPv6 communications from source to destination. IPv6 address representation. The IPv6 addresses are 128 bits in length and written in hexadecimal. IPv6 addresses are not case sensitive and can be written in either lowercase or uppercase.
So like for example if you have like 0db8 this db can be capital lowercase or uppercase it doesn't really matter. The preferred format for writing an IPv6 address is we have a value here and we have two dots like this and then we have value here and dot and those notations and then on go on from left read from left to right with each x consists of four hexadecimal values so when you read from left to right each of these x's contain four hexadecimal values in ipv6 a hex stat is the unofficial term used to refer to a segment of 16 bits or four hexadecimal values example of an ipv6 address in the preferred format can be seen here for example we have 2001 and then we have a value here and then we have value here value here value here value here and each of them are separated with all of this particular notation which is of each of these section position containing a 4 hexadecimal value. So we're going to look at some rules related to writing down or representing IPv6 addresses.
So the first rule is omit leading zero. So this is to help reduce the notation of IPv6 addresses so by omitting the leading zeros of a address. An example would be if you have a value of 0 1 a b that can also be represented as 1 a b.
0 9 f 0 can be represented as 9 f 0 and so on and so forth. So if you have 0 0 a b it can be just represented as just a b because the leading two zeros are not needed. This rule only applies to leading zeros and not to trailing zeros because the trailing zeros do play a part in the value itself so if you look at the preferred address we're going to have an ipv6 address example here with 2001 0 db8 0 0 0 0 1 1 1 1 1 0 0 0 0 and zeros here and 0 and 2 0. now what we're going to do we're going to remove the leading zeros based on the rule number one So in here there are no leading zeros because these zeros are in between two numbers And if you go to the next value next next position the value has a zero at the lead So we're going to remove that and we're going to end up with db8 in here We have four zeros in this position.
That means except for that last zero Everything else the leading zeros doesn't matter So we're going to drop all of those zeros and just leave the zero the last zero there there are no zeros here and again we have the same thing here as here we have zero three leading zeros at the front and then we're gonna drop all of those three zeros and we're gonna leave that final last zero at the end and same here and same thing here and in here we have a leading zero we have a value and we have two uh trailing zeros remember we cannot drop the trailing zeros so we're gonna drop the leading zero and then we leave the trailing zero so we end up with this ipv6 address from the preferred format ipv address So, that's one of the first rule of representing IPv6 addresses, omitting the leading zero. These rules are very important concepts for your Cisco Netacad exams and Cisco CCNA and CCNP exams. So, make sure you understand that. So that's one of the first rules that we do, which is called the omit leading zero.
The second rule is double colon rule. In IPv6 address, the double colon can be represented. can replace any single contagious string of one or more 16 bit hex texts consists of all zeros.
So what does that mean? So that basically means if you have an IPv6 address in this example we have 2001 DB8 CAFE 10001 these zeros can be dropped so basically a double colon can be replaced any single a string of one or more 16-bit hextechs consist of all zeros so because these are all containing zeros what we can do is we can to put two double colons and we can have 2001 colon db8 colon CAFE colon 1 and now when we come to these three zeros we're gonna put two colons So double colon and then we're gonna put one so we basically drop all of those zeros because it doesn't need to be represented We know those zeros exist there the double colon can only be used once within an address Otherwise there would be more than one possible resulting address So what that basically means is if you have another set of zeros like this in the same same IPv6 address you can't just use double zero twice. So you can't have a double zero here if we have a bunch of zeros here you can't have double colon here and a double colon here because that's going to be resulting in confusing IPv6 addresses.
So it can only be used once. An example here shown with 2001 DB8 000 111 zero two zero what we're gonna do we will drop these values these zero values and use double colon to represent it so the same preferred ipv6 address format can be represented as 2001 colon db 8 colon 0 colon quadruple 1 so 1 1 1 1 now we have double colon here and then 200. remember we use both rules now rule number one and rule number two we drop the leading zeros for example 0 db8 is represented by db8 and these four zeros is represented by just a zero and we also use a rule number two which is using the double colon and we remove those zeros and we put the double colon and then finally 200 by dropping the leading zero so that's those are the two rules of representing ipv6 addresses especially on your papers and documentations as well as when you are entering into some of the devices in devices manually typically we don't actually use a manual entries of ipv6 addresses for end devices we typically use a dscp but if you have to manually enter to a device you can use this notation to enter it to a device ipv6 address types So we have unicast multicast and anycast. These are the three types of categories for ipv6 addresses.
Unicast uniquely identifies an interface on an ipv6 enabled device and multicast is used to send a single ipv6 packet to multiple destinations and anycast is any IPv6 unicast address that can be assigned to multiple devices. A packet sent to an unicast address is routed to the nearest device having that particular address. Unlike the IPv4, the IPv6 does not have a broadcast address.
However, there is an IPv6 all node multicast address that essentially act similar to the IPv4 broadcast addresses. IPv6 prefix length. The prefix length is represented in slash notation and is used to indicate the network portion of an IPv6 address. The IPv6 prefix length can range from 0 to 128. The recommended IPv6 prefix length for LAN and most other types of networks is slash 64. So when it comes to the point of hype, IPv6 typically use prefix length it should be slash 64. that's what the recommended one. so this is actually showing that slash 64 prefix length so we have the prefix with the 64 bits and the interface id with another 64 bit that can be represented with the hexadecimal value on this the prefix like this and the interface something like that Note it is strongly recommended to use 64-bit interface ID for most networks.
This is because the stateless address auto configuration or slack uses 64 bits for the interface ID. It also makes subnetting easier to create and manage. And in terms of what is slack and how it operates we will go over that in a later lecture and as we move through these slides.
Just know that it is part of the IPv6 IP address handling protocols. Types of IPv6 unicast addresses. Unlike IPv4 addresses that have only a single address, IPv6 addresses typically have two unicast addresses. This is a very important concept that you should understand.
in terms of differences between ipv4 and ipv6. so these two unicast addresses are the global unicast address or gua and link local address which is lla. so the global unicast address or gua is similar to the public ipv4 address.
these are the global unique internet routable addresses. so these are the ipv6 addresses that are globally available for routing. And then the local as the link local address or LLA is similar to what the IPv4 have for link local which required for every IPv6 enabled device and used to communicate with other devices on the same local link.
So LLAs are not routable and are confined to that single link and the single network link while the global unicast address GUA is the globally unique IPv6 addresses that are used for internet routing so on the right hand side of this page you can see you have the IPv6 unicast addresses and we have global unicast and link local And then we also have the other divisions such as the loopback, unspecified addresses, unique local addresses and embedded IPv4. So these are the divisions that we have within the IPv6 unicast addresses. For your exams, you should be able to define GUA, LLA and how that is differ from the IPv4 and what are the items that we use in IPv4.
If you are interested in the IPv4 addressing scheme, please go and check my video on the IPv4 addressing scheme that I have posted previously. That will give you an idea about the information you need to know about the IPv4 addressing. A note about unique local addresses. The IPv6 unique local addresses range from FC00:// slash 7 to fdff double colon slash 7 have some similarity to rfc 1918 private address for ipv4 however there are significant differences a unique local addresses are used for local addressing within a site or between a limited number of sites A unique local address can be used for devices that will never need to access another network. The unique local addresses are not globally routed or translated to a global IPv6 address.
So you should know these key features of the IPv6 unique local addresses. So they are used for local addressing within a site or between limited number of sites. They are never needed, they were used for devices that never need access to the another network.
So they are like isolated devices and these unique local addresses are not globally routed or translated. to a global ipv6 address so those are the three key features that you should know about the unique local addresses please not many sites use the private nature of rfc 1918 addresses to attempt to secure or hide their network from potential security risk this was never intended use of the ula so as i mentioned before you can isolate devices using those unique The IPv6 global unicast addresses are globally unique and routable on the IPv6 internet. In other words, this is the address that can be used to connect global networks.
Currently, only GUS with the first three bits of 001 or 2000 double colon slash 3 are being assigned. Currently available GOS begins with a decimal 2 or a 3. This is only 1 8th of the total available IPv6 address space. So on a Cisco Netacad CCNA or CCNP exam, this is a question that you might get because I got this question on my exam that they will give you an IP address for IPv6 on a multiple choice and as which of these IPv6 addresses are considered as global unicast addresses. The way you remember this for your exams is that currently only GUS with the first three bits of 001 or 2000 colon colon slash three are being assigned and if you see that value of in the one of the answers for your exams and that's what you should be picking and you should also know Currently we only have assigned 1 8th of the total available IPv6 address space allocated to these GUAs for global IPv6 routing.
And this diagram below is just basically showing that in a graphical format. IPv6 GUA structure There are three parts to IPv6 GUA structure. Global routing prefix, subnet ID, and interface ID. The global routing prefix is the prefix or network portion of the address that is assigned by the provider, such as an ISP, to a customer or the site. The global routing prefix will vary depending on the ISP policies.
Subnet ID field is the area between the global routing prefix and the interface id. The subnet id is used by an organization to identify subnets within its site. Interface id basically is the ipv6 interface id that is equivalent to the host portion of an ipv4 address. You know how in an ipv4 address the last octet is acting as the host portion. In IPv6 addresses, the interface ID is pretty much doing the similar thing as the host portion of the IPv4 address.
And it is strongly recommended that in most cases, you slash 64 subnets to be used as interface IDs in IPv6 addressing scheme, which will create a 64 bit interface ID. For your Cisco CCNA CCNP exams, you should know these terms and what they actually mean so that you will be able to have a better idea about how the IPv6 GUA structure works. Note IPv6 allows the all zeros and all ones host addresses that can be assigned to a device. The all zeros address is reserved as a subnet router, anycast address. and should be assigned only to routers.
So that's a key thing that you should also know. IPv6 LLA An IPv6 link local address or LLA enables a device to communicate with other IPv6 enabled devices on the same link and only on that link. This same link or only on that link can be also described as a subnet. Packets with a source or destination LLA cannot be routed.
Every IPv6 enabled network interface must have an LLA. If an LLA is not configured manually on an interface, the device will automatically create one. And the IPv6 LLAs are in the a fe80://10 range and in the diagram below right here is describing how LLA works.
So the router use the LLA of neighbor routers to send routing updates. So the LLAs are used between the router neighbor router and routers and the hosts use the LLA of a local router as the default gateway. When we have two routers communicating between each other using routing protocols, the LLAs of the neighbor routers are used to send those updates between the two routers and the host will use the LLA of a local router as their default gateway. GUA and LLA static configuration. Static GUA configuration on a router.
Most IPv6 configuration and verification commands in Cisco IOS are similar to their IPv4 counterparts. In many cases, the only difference is the use of IPv6 in place of IP within the commands. I will do a live demonstration of Cisco labs with IPv6 and how you can assign IPv6 addresses so that you will have a better idea of what exactly this slide is talking about.
But here what you need to understand is the command to configure an IPv6 GUA on an interface is just IPv6 and then you put the IPv6 address and then you put the IPv6 address slash the prefix length. For example, uh in this example we have ipv6 address so that's the command ipv6 address and then we're going to put the address here and slash whatever the prefix length in this here is the 64. so that's what this example is showing and this particular command this particular ip address i mean is being entered into the interface gigabit zero zero zero because we are in the configuration of that particular interface and issuing the no shutdown command we basically put this interface into uh you know back onto online with that ipv6 address manually configuring ipv6 address on a host is similar to how we manually configure an ipv4 address the gua or lla of the router interface can be used as the default gateway. So in here the default gateway is the gu or the ll of the router interface.
Just like in ipv4 addresses where you put the default gateway as the interface of your router we use the gu or ll of the router interface for ipv6 default gateway. The best practice is to use the ll. But you can use either one that should work When DHCPv6 or slack is used, the LLA of the router will automatically be specified as the default gateway address.
So we can use either GUA or LLA when you manually configuring it but if you are using the DHCP IPv6 address, it will always be the LLA address that will be assigned as the default gateway. If you look at the right hand side of your screen this diagram basically showing that manually entering it. One of the key difference here I would like to point out to anybody who is studying for these classes is that in IPv4 you know you had to enter the entire subnet prefix but here we just put the subnet prefix length which is 64. Remember if this is IPv4 we'll be entering like 255.255.2550 for example in here instead of putting the slash 24 or something slash 36 or etc etc in here we just put the prefix length which is 64. this is made that way so that it is easy for humans like you and me to do network configurations configuring the llas manually lets you create an address that is record and easier to remember.
LLAs can be configured manually using the IPv6 address by entering you know IPv6 address and then the link local address and then put link local command and then that will give you the LLA assigned within your Cisco router. So in Cisco ISO devices the ISO software firmware this is an example where we assign an LLA to the port the interface G000 on R1 the router one so just like before we enter the configuration mode of that port and we give ipv6 address this is the command ipv6 address and then we give that link local address and then we enter the command link local right behind it and press enter and then by putting it into no shutdown command what we do actually we put this interface online with this particular LLA address not the same LLA can be configured on each link as long as it is unique on that link so that is a very important concept the same LLA can be configured on each link as long as it is unique on that particular link common practice is to create a different LLA on each interface of the router to make it easier to identify router and specific interfaces. So if you have different interfaces it is common to create different LLAs for each interface. So if you go to gigabit ethernet 001 for example you will create another inter the LLA value for your link local so that it is unique for that each interface of that router. Dynamic Addressing for IPv6 GUAs RS and RA Messages RS is the router solicitation and RA is router advertisement Devices obtain GUA addresses dynamically through Internet Control Message Protocol version 6 which is known as ICMPv6 Messages Router solicitation or RAs messages are sent by host devices to discover IPv6 routers, while router advertisement or RA messages are sent by routers to inform host on how to obtain an IPv6 GUA and provide useful network information such as network prefix and prefix length, default gateway address, DNS address and domain name.
The RA can provide three methods for configuring an ipv6 gua those are slack slack with stateless dhcp v6 server and stateful dhcp v6 server which doesn't have the slack for this particular course you just need to know what rs and ra you know how they differ from each other and how uh each of them can provide different services within this ipv6 um you know system In my future courses we will go into depth of RS and RA. So for now we just gonna you know brush the surface of these concepts. Dynamic addressing for IPv6 GUAs the method one which is slack. So slack allows a device to configure a GUA without the services.
of a DSCPv6. Devices obtain the necessary information to configure GUA from the ICMPv6 RA messages of the local router. The prefix is provided by the RA and the device uses either EUI-64 or random generation method to create an interface ID.
So this is an important concept. So the prefix is provided by the RA. is provided by the RA and the device can create the you know device can use either the EUI-64 or random generation method to create an interface id so either one would work and this is what is shown in the diagram here So you get a message from the RA with the prefix on it and the interface id either created by the client device itself using the EUI-64 configuration method or random 64 bit number. The second method is slack and stateless DSCP.
How that's going to work is an RA can instruct a device to use both slack and stateless DHCP v6. The RA message suggests devices use the following. It will give the slack to create its own IPv6 GUA, the router LLA which is the RA source of IPv6 address as the default gateway address, and a stateless DHCP v6 server to obtain other information such as DNS server, address and the domain name so the diagram here describe how the process for slack and stateless dhcp works so we have a rs message sent from your device to the router and the router send an ra message back to the device with the dhcp version 6 information the server information and then the device get the that information get forwarded to that stateless dscp version 6 server and that's how the device can obtain the information needed to connect to the network the third method is the stateful dscp version 6. an ra can instruct a device to use stateful dscp version 6 only in stateful dscp version 6 what happened is it is very similar to gscp for ipv4 A device can automatically receive a GUA, prefix length, and the address of the DNS servers from a stateful DSCP v6 server. The RA message suggests devices use the following. The Router LLA which is the RA source of the IPv6 address for the global gateway address.
A stateful DSCP v6 server to obtain a GUA DNS server address, domain name and other necessary information. And on the bottom of the screen, it is visually describing how the stateful DSCPv6 works. So you have your device trying to connect to the network. It sends a RS message and it goes into the router and the router sends the RA message back and it will go and solicit the DSCPv6. and that's how we're going to get all the information necessary to connect to the network eui-64 process versus random generated and on my previous slide we briefly brush over what ui64 and random generation but we didn't go into depth and here we're going to explain that a little bit in more detail but again we are not going into too much detail in this class but this is all you need to know.
So when the RA message is either slack or slack with stateless DSCP version 6, the client must generate its own interface id. The interface ID can be created using two methods either UI slash 64 process or randomly generate a 64-bit number. So how it's going to work is basically we have ICMP v6 router advertisement and it goes to your end device and the end device has to use that message RA message as the prefix and then create that interface ID randomly so that it is unique to this particular device and connect to the network. So we're going to look at it in a little bit more detail about how EUI-64 work now. EUI-64 process.
The IEEE defined the extended unique identifier or EUI, which is a modified version of the EUI-64 process that performs the following. A 16 bit value of FFFE in hexadecimal is inserted into the middle of the 48 bit ethernet MAC address of the client. The 7th bit of the client MAC address is reversed from the binary 0 to 1. And that's how you get the EUI-64 process to obtain.
that particular value. So in this example we have a 48-bit MAC address and that would be FC994775CE0 and the UI-64 interface ID use that 48-bit MAC address and use these principles above to generate that interface ID. So it use that MAC address and it takes fc and convert that into fe and it takes this f this value they insert these two values ff and fe to generate that unique interface id so this is an important concept that you understand and how it works for your exam so if you would like to have a summary you can come back to this slide for your exams and quizzes Next, we gonna look at the other method which is the randomly generated interface IDs. So how it works is depending on the operating system, a device may use a random generated interface ID instead of using the MAC address and the EUI-64 process.
So beginning with the Windows Vista, Windows uses a randomly generated interface ID instead of one created by EUI-64. so if you are using any windows computers starting from windows vista all the way to windows 11 they all be will be using the randomly generated interface id and if you go to your windows computer and you go into command prompt and if you type ipconfig and the ipv6 address information that is showing up on your command prompt is actually created using the random generated interface ids not to ensure the uniqueness of any ipv6 unicart address the client may use a process known as duplicate address detection or dad so this is very similar to an up request for its own addresses if there is no reply and then the address is unique so what's going to happen is in this case when the randomly generated address is created by the Windows machine, it's going to use the DAD duplicate address detection process to make sure that this address is unique within that network. And if it is not unique, what's going to happen is it's going to generate a new address until it is absolutely sure that there are no duplicate addresses within that network. Dynamic Addressing for IPv6 LLAs. Dynamic LLAs are all IPv4 interfaces must have them.
So all IPv6 interfaces will have an LLA associated with it. Like IPv6 GUAs, LLAs can be configured dynamically. The figure shows the LLA is dynamically created using fe80://10 prefix and the interface id using UI-64 process or randomly generated 64-bit number.
So we have the fe80://10 so that's that's the prefix right here and we are using 64-bit value at the interface you know interface ID right down here so this is this is just diagram is just summarizing what is described above here so that's how the dynamic LLS work dynamic LLS on Windows operating systems such as Windows will typically use the same method for both slack created GUA and a dynamically assigned LLAs. So the UI-64 generated interface ID looks like this and then the random 64-bit generated ID looks like that. You don't need to know how to identify them on an exam because there's no such thing as like just identifying them between the two but just Just remember, there's UI64 generated interface ID and random64 bit generated interface ID both exist in IPv4 configurations. Cisco routers automatically create an IPv6 LLA whenever a GUA is assigned to the interface.
By default, Cisco IOS routers use UI64 to generate the interface ID for all LLAs. and IPv6 interfaces. So this is an important concept that might show up on your CCNA and CCNP exam. I got this question asking you know what is the default of Cisco ISO routers and by default all Cisco IOS routers use the EUI-64 to generate the interface ID so you should know that. And in here on the bottom of the screen is an example of LLA dynamically configured on this particular interface gigabit ethernet 000 on our R1 router.
Again you can pause this video if you want to have a look at it but what's important is not that you understand how you know how these things work in you know in detail these numbers what you need to know is how to identify those numbers on a cisco router if they give you this image or to and also to understand that the cisco iso routers currently use ui-64 by default to generate those ids that's the important thing you need to get out of this slide verify ipv6 address configuration on a cisco iso device what you can do actually you can run the show interface gigabit ethernet zero zero zero or show interface whatever the interface you're gonna have on your router it doesn't need to be gigabit ethernet zero zero zero whatever the interface you want to look at and that will show you the information related to that ipv6 configurations so if there is ipv6 configuration attached to that cisco router you should be able to look that information up uh by just going through that process The other command that you should know is the show ipv6 interface brief that will also give you some additional information about the configurations the same same information actually with the configuration related to that IPv6, so that's what this slide trying to get you and The information about here is the same as the previous slide. There's a packet tracer lab available to you on your cisco netacad if you have access to cisco netacad and go ahead and do it and it will explain how you can configure ipv6 addresses and test and verify those network connectivity the lab is titled configure ipv6 addressing and if i get hold of these labs i will post them on my website so that you have access to them if you have access to your cisco netacad you can go ahead and do them IPv6 Multicast Addresses Assign IPv6 Multicast Addresses IPv6 multicast addresses have the prefix of ff00://8. There are two types of IPv6 multicast addresses.
Well-known multicast addresses. Solicited node multicast addresses. Multicast addresses can only be destination addresses and not the source addresses. So those are very important concepts.
So there are two types of. IPv6 multicast addresses, well-known multicast addresses and solicited node multicast addresses. And the multicast addresses can only be destination addresses and not the source addresses.
Well-known IPv6 multicast addresses. A well-known IPv6 multicast addresses are assigned and are reserved for predefined groups of devices. And there are two common IPv6 assigned multicast groups. They are all nodes multicast group and all routers multicast group. The all nodes multicast group is associated with ff02 colon colon 1 and this is a multicast group that all IPv6 enabled devices join.
A packet sent to this group is received and processed by all IPv6 interfaces on the link or the network. the ff02 colon colon 2 which is associated with all routers multicast group and this is a multicast group that all ipv6 routers join a router becomes a member of this group when it is enabled as an ipv6 router with the ipv6 unicast routing global configuration command and these are two important things that you should know about the two common IPv6 assigned multicast groups. So let's look at the Solicited Node IPv6 Multicast. A Solicited Node Multicast address is similar to the All Nodes Multicast address.
A Solicited Node Multicast address is mapped to a special Ethernet Multicast address. The Ethernet Network Interface card can filter the frame by examining the destination MAC address without sending it to the IPv6 process to see if the device is the intended target of the IPv6 packet. The Ethernet network interface card can filter the frame by examining the destination MAC address without sending it to the IPv6 process to see if the device is the intended target of the IPv6 packet.
and this is what they are trying to explain here with this particular diagram on the right hand side i'm not going to go over it into detail you can post this video if you would like to look at it there's a lab available to you on your cisco netacad called identify ipv6 address if you have access to this particular lab through your cisco netacad go ahead and do it and if you don't i will try to obtain a copy of this lab and post it on my website so you can go ahead there and do it i would recommend doing these labs as you go through this module so that you have a better idea of all the concepts that we were going to cover subnet and ipv6 network subnet using the subnet id ipv6 was designed with subnetting in mind A separate subnet id field in the ipv6 gua is used to create subnets. The subnet id field is the area between the global routing prefix and the interface id. So we have the global routing prefix here and the subnet id with the 16 bit in the middle and we have the interface id behind it. So we have 48 bits for the global routing prefix and we have 16 bit for the subnet id. and the 64 bit for the interface id like in here a 48 routing prefix plus 16 bit subnet id equal to 64 bits prefix so that's how it gives you the 64 prefix up here that includes the subnet id given the 2001 colon db 8 colon c sorry ac ad colon colon slash 48 global routing prefix with a 16-bit subnet id we can allow 65 536 slash 64 subnets the global routing prefix is the same for all subnets and only the subnet id hextech is incremented in the hexadecimal for each subnet so that's what is showing on the right hand side of the screen here and i again i'm not going to go through this in detail in this particular course also you should realize that you don't need to know exactly how everything works with subnetting with respect to ipv6 but you should know how to subnet ipv4 so that's another important thing about this course ipv6 subnet allocation the example topology requires five subnets one for each land as well as for the serial link between r1 and r2 so this is the topology that we have down here so we have a serial link between r and r2 and then we have five subnet one two three four and plus this one right so the five ipv6 subnets are were allocated with the subnet id field 001 to 005 each with slash 64 subnet will provide more addresses than will ever be needed so that is shown here on the right hand side right here with this diagram with respect to the left hand side topology we have here. Router configured with IPv6 subnets.
The example shows that each of the router interfaces on R1 has been configured to be on a different IPv6 subnet. So if you look at this example here we have R1 the router 1 and this Cisco IOS device. sorry cisco ios device we have the interface uh zero zero zero here and it has a particular ipv6 subnet and then the next interface have a different ipv6 subnet and the next one has a different ipv subnet see one two three is actually changing so that's what it's shown here for your module quiz and exams all you need to know is that basically you know how to identify different subnets by just looking at this sometimes but you don't need to know in detail exactly everything to go with ipv6 subnetting for this particular model but you should know the ipv4 as i mentioned before what did we learn in this lecture there are several packet tracer files and lab files available to you on your cisco netacad that will cover everything we covered in this particular lecture but if you do not have access to those labs on netacad i will see if i can get the copies of them and post it on my website so you can go ahead and do them and if you do have access to it it is called the implement a subnetted ipv6 addressing scheme and that will go over everything we just covered again there is a lab called configure ipv6 addresses on network devices that will also cover uh some of the topics that we covered in this particular lecture if you have access to them i would highly recommend doing them because it will encompass everything that we just covered so let's look at a summary of everything we learn in this lecture we learn ipv4 has a theoretical maximum of 4.3 billion addresses hence we are actually running out of those ipv4 addresses the IETF has created various protocols and tools to help network administrators migrate their networks to IPv6.
The migration techniques can be divided into three categories, dual stack, tunneling, and translation. And remember, I mentioned the dual stack is something that you probably going to see, most likely going to see in the field in 2022 as we are in the transition phase of the IPv4 to ipv6. Also, I believe that this is gonna take several decades for us to completely transfer into ipv6 from ipv4. IPv6 addresses are 128 bits in length and written as a string of hexadecimal values.
The preferred format for writing ipv6 address is shown here with those colons separating each of these positional values. with each x consists of a four hexadecimal value so each of these x represent four hexadecimal values There are three types of IPv6 addresses. Those are unicast, multicast and anycast and you should be able to describe them and how they are different from each other.
An IPv6 unicast address uniquely identifies an interface on an IPv6 enabled device. IPv6 global unicast addresses known as GUS are globally unique and routable on IPv6 internet. An IPv6 link local addresses such as known as LLAs enable a device to communicate with other IPv6 enabled devices on the same link and only on that link which can be considered as a subnet. The command to configure an IPv6 GUA on an interface is IPv6 address on a Cisco IOS device.
and then you after that command ipv6 address you can enter the ipv6 address slash the prefix length and that will allow you to configure the ipv6 gua on a cisco device a device obtains a gua dynamically through icmp version 6 messages ip version 6 routers periodically send out icmp version 6 router advertisement messages or ra messages every 200 seconds or so to all IPv6 enabled devices on the network. So remember that. A device obtains a GUA dynamically through ICMPv6 messages and IPv6 routers periodically send out ICMPv6 RA messages every 200 seconds to all IPv6 enabled devices on the network.
RA messages have three methods slack slack with stateless dhcp version 6 server and state full dhcp version 6 with no slack you should know how each one of these things works in general for your exams and quizzes the interface id can be created using the eui-64 process or randomly generate a 64 bit number the euis Process uses the 48-bit ethernet MAC address of the client and insert another 16-bit in the middle of the MAC address to create a 64-bit interface ID. Depending upon the operating system, a device may use a randomly generated interface ID or may use the EUI-64 method. All IPv6 devices must have an IPv6 LLA An LLA can be configured manually or created dynamically.
Cisco routers automatically create an IPv6 LLA whenever a GUA is assigned to the interface. That is an important concept that may show up on your CCNA, CCNP exams. Cisco routers automatically create an IPv6 LLA whenever a GUA is assigned to the interface.
There are two types of IPv6 multicast addresses. Those are well-known multicast addresses and solicited node multicast addresses. Two common IPv6 assigned multicast groups are FF02, FF02, FF02, and FF02, and FF02, is associated with all node multicast group which are used by mostly device used by devices while the ff02 colon colon 2 is used by all routers with multi in that multicast group a solicited node multicast address is similar to the all nodes multicast address the advantage of a solicited node multicast address is that it is mapped to a special ethernet multicast address IPv6 was designed with subnetting in mind.
A separate subnet ID field in the IPv6 GUA is used to create those subnets. But however, as I mentioned before, unlike IPv4 subnetting, you know, we are not going to do a lot of IPv6 subnetting in this particular course. And that will bring us to the end of this lecture.
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And until our next lecture, good luck with your exam and have a nice day.