3 ms·
Why does it all start with "2"? e.g. 2000 -> 2f00? Where are the other prefix segments?
by nvahalik 4y ago
Why does it all start with "2"? e.g. 2000 -> 2f00? Where are the other prefix segments?
- Melkman 4y agoBecause IANA started delegating prefixes starting with 2. And haven't done enough delegations to go to 3. Prefixes starting with 0 of F are also in use for mapping IPv4 addresses to IPv6, link local and multicast adressing and other special needs.
- nibbleshifter 4y agoAs yet unissued, according to the page.
- throw0101c 4y ago> Where are the other prefix segments? Currently not needed. The IETF/IANA folks were a bit cautious, so only 2000::/3 is officially designated to be assigned. If, a few years down the road, they find out that a mistake was someone made in address allocations, they can then 'start over' from the lessons learned, and start assigning things from 4000::/3. If they made a mistake again, they can start over again with 6000::/3. And then 8000::/3, a000::/3, and c000::/3. * https://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml https://www.iana.org/assignments/ipv6-address-space/ipv6-add... So that's why all global unicast addresses start with 2: they're to be 'conservative' in what is usable so that if there are problems there is room for corrections in the coming years/decades/centuries. We don't want to have to go through another IP protocol transition.