Introduction to IPv6

Size of IPv4 is 32-bits only, while IPv6 is 128-bits and it is represented in hexadecimal numbers in the form of X.X.X.X.X.X.X.X which X consists of 16-bit value. Example expression of IPv6 is 2000:0000:1234:ABCD:0000:0000:FACE:00006. This can be written as 2000:0:1234:ABCD:0:0:FACE:0006 or simplified to 2000::1234:ABCD:::FACE:6. If we find the address is 2000::A, it is also can be written as 2000:0:0:0:0:0:0:000A.

            Let’s take a look at this example of CIDR X:X:X:X:X:X:X:X/64. It means that the network is 64-bit, and we can calculate like Figure 1, and hence we get N.N.N.N.H.H.H.H. IPv6 does not have broadcast and network address translation (NAT). However, similar to IPv4, IPv6 has unicast and multicast. IPv6 is faster because of no broadcast. It can access anywhere, and everyone gets public IP. The differences between IPv4 and IPv6 are summarized in Table 1. We will discuss further the range of global unicast, link-local and multicast in the next volume.

Figure 1 CIDR in IPv6

Table 1 IPv4 vs IPv6

IPv4	IPv6
32-bit (decimal)	128-bit (hexadecimal)
Public IP	Global unicast 2000::/3
Private IP	Link local FE80::/10
Loopback 127.0.0.0 => 127.255.255.255	::1
Multicast 224-239	Multicast FF00::/8

IPv6 can be anycast i.e. one to nearest. Same IPv6 can be assigned to many hosts. Refer to the Figure 2, if we are in Malaysia and we do not have the server in Malaysia, we can anycast to the nearest, and it is Singapore server.

Figure 2 IPv6 anycast

Reference: CCNAX Training Materials

Written by SIti Sara Rais