IPv6 Part III: Types of IPv6 Addresses (Unicast, Multicast & Anycast) | CCNA
In this video tutorial, I have explained different types of IPv6 Addresses.
There are three types of IPv6 Addresses. They are Unicast, Multicast and Unicast.
Any address that we can assign to any networking device in a network address is unicast address for one-to-one communication.
Multicast address is something like Class D address as in IPv4 address which can be used for multi-casting services. Multicast addresses identify a group of interfaces in such a way that a packet sent to a multicast address is delivered to all of the interfaces in the group. There is no broadcast address in IPv6, that’s taken over by multicast address.
Now, an IPv6 anycast address is an address that is assigned to more than one interface (typically belonging to different nodes), where a packet sent to an anycast address is routed to the nearest interface having that address, according to the routing protocol’s measure of distance. We will talk in detail about the Unicast address in detail later on the video.
So, let’s start with Unicast Address. Inside the unicast address, there are three different categories. We can also call them the sub-categories of a Unicast address and they are :- Global Unicast, Unique local and link local addresses.
Global Unicast addresses are more like public addresses. If you remember public IP, it’s a globally unique IP address and is routable in the internet. You can assign any public IP, which is globally unique on any interface and that is routable on the internet. So, global unicast address is more like public IP address.
Any address that starts with 2000:/3. The /3 represents that the first 3 bits will always be constant. When we have 2 and if we convert it to binary, we get 0010. Here the first three bits or the 001 is constant which is assigned by IANA. IANA stands for Internet Assigned Numbered Authority, it is the global body to regulate Internet Addresses like IP address.
The first three bits which in my case is 001 is fixed, it will not change. If I write the another possible value, I can write 001, because I cannot change it, and I can write the last value also to 1. Because, in binary, either I can write 0 or 1. And all the remaining bits I can change except the first three bits.
So, if you write this in hexadecimal value, it will be 2. And if you write it on hexadecimal value, it will 2+1= 3. So, whichever IPv6 address, that starts with 2 or 3 in the first portion, we have to understand that these addresses are Global unicast addresses. This is something defined by IANA, it’s the standard.
Now, the second category of Unicast Address is unique local. Unicast unique local address is more like private IP address and it’s routable. IANA has decided that FC00::/7 is the Unicast local address. Which means the first seven bits of the address is constant or fixed.
Unique local addresses are not routable in the IPv6 internet same as IPv4 private addresses. Remember IPv4 private IP addresses are not routable in the internet but they are routable in the local area network. And any address whichever starts with FC or FD in the first two are identified as the unique local addresses.
Same as the global unicast address calculation process, the link local address starts with either FC or FD.
Now, the third category of IPv6 unicast address is link local address. Link local address is the default IPv6 address which is enabled on every IPv6 interface. The link local address is not routable. T
So, unicast addresses are the addresses that are most commonly used by the network administrators while setting up an IPv6 network.
Multicast address is more similar with Class D IPv4 addresses. When a copy of packet is sent to multiple devices at the same time, then that’s multicasting. Networking devices on IPv4 network, use class D address for multicasting.
But in IPv6, multicast address will start with FF and by default FF00::/8 which is defined by IANA. The /8 means the first 4 bit and the second 4 bit will remain constant. They can’t be changed. Any address that starts with FF in the first block is multicast address.
Finally, we have Anycast address. Anycast address is quite similar to multicast address, but the difference is it sends only one interface whichever it finds first or whichever is measured as the nearest interface.
So, an anycast address is an address that is assigned to a set of interfaces that typically belong to different nodes where a packet sent to an anycast address is routed to the nearest interface having that address, according to the routing protocol’s measure of distance.
Anycast address is more commonly used in scenarios where you implement multiple gateways acting as a single gateway.
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