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> However, that only works with a /64 prefix Well it should be redesigned so it works all the way down to individual addresses.
by londons_explore 3y ago
> However, that only works with a /64 prefix
Well it should be redesigned so it works all the way down to individual addresses.
- greyface- 3y agoYou can use DHCPv6 instead of SLAAC if you need autoconfiguration on sub-/64 prefixes.
- scheme271 3y agoSome systems like android don't support anything but SLAAC
- ale42 3y agoIMHO it means that they are not fully IPv6 compliant. Corporate networks often have DHCPv6 rather than just SLAAC.
- bert64 3y agoThey are fully compliant, SLAAC is part of the standard whereas DHCPv6 is an optional extra. DHCPv6 also does not work without RA. DHCPv6 just assigns an address, a routable prefix, dns servers etc, it does not assign a subnet or any routes, you need route advertisements for that.
- ale42 3y agoSeen like this, you can also argue that DHCP is an optional extra for IPv4, but it almost essential in most networks. Sure, IPv4 has no SLAAC that can be a valid alternative, but still, given that SLAAC doesn't solve every use case...
- lmm 3y ago> Well it should be redesigned so it works all the way down to individual addresses. Why? What's wrong with how it works at the moment?
- Kab1r 3y agoI actually have the issue where my ISP gives me a single /64 and it makes it difficult to split between multiple LANs.
- lmm 3y agoPublished guidance says they're meant to give out at least a /56. I don't know that making autoallocation work on smaller subnets would help with this problem - ISPs that currently give out the smallest possible subnet would probably just switch to whatever the new smallest possible subnet was.
- Kab1r 3y agoThere probably is a way to ask my ISP for a larger block, but I think it would be nice to be able to subnet a /64 regardless.
- lmm 3y agoCIDR and the resulting address space fragmentation was the problem that IPv6 was originally meant to solve; allowing splitting into random-sized subnets makes routing more complex and worse. And if you made the routable part of an IPv6 address longer than 64 bits then that makes the routing much more compute-intensive. 64 bits in the local part of the address is sort of overkill, but a 128 bit address isn't really any harder to use than a 96 bit address, and it means things like, well, being able to automatically assign the local part based on the MAC address, which only works if the local part of the address is more than 48 bits.
- londons_explore 3y agoYou can still use a shorter hash of the Mac address. Collisions are very unlikely, and a quick ARP packet should detect them if they do happen.
- pantalaimon 3y agoThere was a proposal for that: https://www.ietf.org/archive/id/draft-mishra-6man-variable-slaac-08.html https://www.ietf.org/archive/id/draft-mishra-6man-variable-s...