ipv6 subnet reserves 2 addresses in allocation pool

[Kirill Shileev]

consider this table:

125::/125 | {"start": "125::1", "end": "125::6"} |
126::/126 | {"start": "126::1", "end": "126::2"} |
127::/127 | |
128::/128 | |

all those subnets created with
neutron subnet-create --ip_version 6 --disable-dhcp --no-gateway NETWORK CIDR

You see that ::0 and the largest address in CIDR are reserved.
This is similar to ipv4 where we have network address and broadcast address, while
according to http://www.iana.org/assignments/ipv6-interface-ids/ipv6-interface-ids.xhtml there should be no this reservation for ipv6.
Situation for prefixes 127 and 128 even worse, no addresses at all.

[Sagi (Sergey) Shnaidman (sshnaidm)]

I suggest such solution:

1) According to IETF all "not /64" subnets in IPv6 are risky, so no strict reservations should be done for them. Also no need to reserve broadcast address for them as it doesn't exist in IPv6. Subnet-router anycast address makes sense in all networks except of /127, /128:

 A) If network mask is between 64 and 127, reserve only subnet-router anycast address, all others should be allocated for hosts.
 B) If network mask is 127 or 128, don't reserver anything.

2) In all /64 and bigger networks all reservations according to "Interface IID" document should be done: http://www.iana.org/assignments/ipv6-interface-ids/ipv6-interface-ids.xhtml

[Armando Migliaccio (armando-migliaccio)]

This bug is > 365 days without activity. We are unsetting assignee and milestone and setting status to Incomplete in order to allow its expiry in 60 days.

If the bug is still valid, then update the bug status.

[Launchpad Janitor (janitor)]

[Expired for neutron because there has been no activity for 60 days.]