Hello Daniel
Concerning statically assigned IPv6 addresses, it depends upon the host you are assigning it to. In general, if you are addressing a server, a printer, or some other device that you want access to, then it is a good idea to use a statically assigned address, keeping in mind that you are certain that the address will not change.
However, this is a little bit of an “IPv4” mentality and is not completely based on the capabilities of IPv6. IPv6 has been designed to be less hands-on and more automatic and intuitive. The use of EUI-64 to obtain an IPv6 address saves time in the configuration as well as determining subnets and addressing. And it will always be unique because the MAC address from which it is derived is unique.
Yes, that is correct. But even if you don’t calculate it yourself, you can always see what address has been assigned simply using show
commands.
The only thing to keep in mind is that if you are using subinterfaces, all subinterfaces of the same physical interface will adopt the same MAC address. So you cannot configure two subinterfaces to use EUI-64 with the same prefix. If you try to do this, you will get the following result:
R3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#inter gig 0/1.10
R3(config-subif)#ipv6 enable
R3(config-subif)#ipv6 address 2001:192:168:12::/64 eui-64
R3(config-subif)#inter gig 0/1.20
R3(config-subif)#ipv6 enable
R3(config-subif)#ipv6 address 2001:192:168:12::/64 eui-64
%GigabitEthernet0/1.20: Error: 2001:192:168:12:5054:FF:FE1B:42A8/64 is in use on GigabitEthernet0/1.10
R3(config-subif)#
Because the same MAC is used, it would result in the exact same IPv6 address. So there you would have to use another prefix (meaning the subinterfaces would be in different subnets, which would be the case most of the time) or you would have to statically assign one of them.
I hope this has been helpful!
Laz