I use an IPv6 tunnel provided by Hurricane Electric to provide IPv6
access for my LAN. HE tunnels are configured statically (no DHCPv6 /
PD involved) and for the purpose of understanding what ranges are
used, assume the following:
WAN - 2001:DB8:DEAD:BEEF::/64 (local tunnel endpoint at
2001:DB8:DEAD:BEEF::2)
LAN - 2001:DB8:CAFE:BABE::/64 (note this is not a subnet of the
WAN, I think this may be important here)
I use both SLAAC + DHCPv6 on the LAN. Devices with DHCPv6 capability
are configured with IPv4+IPv6 addresses in /etc/config/network. This
has worked flawlessly in Barrier Breaker so far. After migrating to
Chaos Calmer, DHCPv6 was essentially broken. Devices that previously
were using addresses configured through DHCPv6 are now using SLAAC only.
Looking in the logs of one of the DHCPv6 clients (a laptop using
NetworkManager), I noticed that it was handed out a lease with a
preferred lifetime of just one (1) second. Consequently, it would
attempt to renew the lease it gets every second, causing intermittent
IPv6 availability (if at all) and huge CPU spikes on the router at the
times the client connected. Reverting back to the version of odhcpd
from Barrier Breaker fixed both these problems and DHCPv6 was useable
again.
Digging into the code, the following commit broke odhcpd in my router
(Netgear WNDR4300):
dhcpv6: allow flash renumbering in hybrid management mode
https://github.com/sbyx/odhcpd/commit/a5ebe69d1bc387937bc5448534751123833585fd
Neither of the following two changes to the same part of this code
fixed things:
dhcpv6: fix calculation of T1 and T2
https://github.com/sbyx/odhcpd/commit/b461334ab277b6e8fd1622ab7c8a655363bd3f6c
DHCPv6: enable flash-renumbering hack only for /64 prefixes
https://github.com/sbyx/odhcpd/commit/3b628005e66e90770b2757a4a02c1dee25ccb883
I'm not quite sure what problem these commits are trying to solve, but
it looks to me that the logic behind it is somehow not working for me.
For all intents and purposes, the IPv6 addresses I use are static, so
I see no reason why it would be necessary to renumber addresses at all.
Any thoughts?
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