IPv6 networks and subnets
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The same prefix (2001:db8:1ad:27b::/64).
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A unique value (for the interface ID) in the remaining 64 bits of the global unicast addresses.
In the above case, if device "A" has an interface ID of 218:71ff:fedd:cf00, its complete global unicast address is:
2001:db8:1ad:27b:218:71ff:fedd:cf00/64
2001:db8:1ad:27b: Prefix
218:71ff:fedd:cf00: Interface ID
/64: Prefix Length
Traffic between hosts on the same network is switched and employs link-local addresses that include a reserved prefix (FE80::/64) and a unique interface ID generated from the device MAC address. Continuing the example from above, device "A" uses the following link-local address for switching:
However, when a packet must be sent from one network to another, where the source and destination have different IPv6 network prefixes, the packet must be routed. For example, routing is required to send traffic between the devices at these two addresses residing in different networks:
2620:0:a03:e102:218:71ff:fedd:cf00/64
1
2001:0:db8:17fd:218:71ff:fedd:cf00/64
2
1,2 Prefix