3 ms·

This may be a dumb question, but why does one need with a /60 ? Isn't a /64 already ridiculously huge to the point that I could never possibly use it all?

snagglegaggle 7y ago
Not with that attitude.
oarsinsync 7y ago
IETF recommend a /64 as the smallest subnet size to use, as stateless auto address configuration (SLAAC) only works with that subnet size. Any user that wants more than a single subnet at home is supposed to receive a /48 by the same recommendation base. A lot of ISPs settled on /56s. Comcast is a bit more stingy than some. That introduces a whole other set of problems.
zaphoyd 7y ago
Not a dumb question at all! The smallest IPv6 subnet is /64, so a /60 lets you split your network into multiple subnets without all the software that assumes a subnet is /64 (like address autoconfig) breaking. Why might you need multiple subnets? Lots of reasons, common ones are for security. It lets you do things like split up a home office network from home from guest wifi from IoT/home automation. Also allows new services to be created that use that capability.
cfallin 7y ago
The RIPE guidelines at [0] line up with what I've heard as justification before: basically, /64 is the smallest you can go without lots of manual configuration (the way that SLAAC auto-assigns addresses from Ethernet MACs or random bytes only works when the host part of the address is 64 bits). There may be valid technical reasons to want > 1 subnet at a customer site. And finally, the space is huge -- an ISP would typically get a /32 at least (Whois says that Comcast is using a /26 just for the Bay area), so if every customer gets a /60, that's 2^28, or 256M, delegations. (With the /26, Comcast could hand out 16 billion /60 delegations to their SFBA subscribers.) [0] https://www.ripe.net/publications/docs/ripe-690#4--size-of-end-user-prefix-assignment---48---56-or-something-else- https://www.ripe.net/publications/docs/ripe-690#4--size-of-e...
anticensor 7y ago
I only need a /100. More internet addresses than Europe has in IPv4. I can statically assign devices their own individual addresses.

snagglegaggle 7y ago

Not with that attitude.

oarsinsync 7y ago

IETF recommend a /64 as the smallest subnet size to use, as stateless auto address configuration (SLAAC) only works with that subnet size. Any user that wants more than a single subnet at home is supposed to receive a /48 by the same recommendation base. A lot of ISPs settled on /56s. Comcast is a bit more stingy than some. That introduces a whole other set of problems.

zaphoyd 7y ago

Not a dumb question at all! The smallest IPv6 subnet is /64, so a /60 lets you split your network into multiple subnets without all the software that assumes a subnet is /64 (like address autoconfig) breaking. Why might you need multiple subnets? Lots of reasons, common ones are for security. It lets you do things like split up a home office network from home from guest wifi from IoT/home automation. Also allows new services to be created that use that capability.

cfallin 7y ago

The RIPE guidelines at [0] line up with what I've heard as justification before: basically, /64 is the smallest you can go without lots of manual configuration (the way that SLAAC auto-assigns addresses from Ethernet MACs or random bytes only works when the host part of the address is 64 bits). There may be valid technical reasons to want > 1 subnet at a customer site. And finally, the space is huge -- an ISP would typically get a /32 at least (Whois says that Comcast is using a /26 just for the Bay area), so if every customer gets a /60, that's 2^28, or 256M, delegations. (With the /26, Comcast could hand out 16 billion /60 delegations to their SFBA subscribers.) [0] https://www.ripe.net/publications/docs/ripe-690#4--size-of-end-user-prefix-assignment---48---56-or-something-else- https://www.ripe.net/publications/docs/ripe-690#4--size-of-e...

anticensor 7y ago

I only need a /100. More internet addresses than Europe has in IPv4. I can statically assign devices their own individual addresses.