/64 addresses for IPv6

[mammador]

/64 is a series amount of nodes for a subnet. Why not simply have options for /80, /96, or even /112?

There should be this option, since not even firms with large networks need a /64 subnet. That's about 4 billion hosts in itself.

 

[Gryz]

Because the guys who designed IPv6 (the protocols, the Best Current Practices and everything else) were pretty clueless.

One practical reason is, I guess, the fact that if you autoconfigure hosts with their MAC address as host part of an IPv6 address, you need a few more bits for subnets. 48 bits in the host part, 64 bits available for your own addressing, that leaves 16 bits for subnets at home (or in your small company). It's kinda like giving everyone a class A IPv4 range.

 

[mammador]

Well from what I understand, /32 is for organisations, and /48 is for LANs/VLANs. so even if there are 65,000 or so LANs per organisation, it means each of these subnets has a shitload of hosts. Per LAN, it's way too much than most firms ever need.

Even in a, say, /80, yes there would be more subnets available, but it simply means a lot more subnets can be conserved. I could live until 100, and I doubt I'd see a subnet with 4 billion hosts in it.

 

[imagoon]

Because the guys who designed IPv6 (the protocols, the Best Current Practices and everything else) were pretty clueless.

One practical reason is, I guess, the fact that if you autoconfigure hosts with their MAC address as host part of an IPv6 address, you need a few more bits for subnets. 48 bits in the host part, 64 bits available for your own addressing, that leaves 16 bits for subnets at home (or in your small company). It's kinda like giving everyone a class A IPv4 range.

I would love to hear your justification for "pretty clueless."

At the moment they could assign every person on earth a /64 and not even break out of "0001" in the first octet pair.

Other than fe80: ARIN hasn't assigned a distribution date for "0002" and above.

/64 is also needed for autoassignment to operate.

 

[imagoon]

Well from what I understand, /32 is for organisations, and /48 is for LANs/VLANs. so even if there are 65,000 or so LANs per organisation, it means each of these subnets has a shitload of hosts. Per LAN, it's way too much than most firms ever need.

Even in a, say, /80, yes there would be more subnets available, but it simply means a lot more subnets can be conserved. I could live until 100, and I doubt I'd see a subnet with 4 billion hosts in it.

It isn't the 4 billion hosts thing really, it is more that using auto assignment, you would never have a conflict. IPV6 is designed for high darkspace.