IPv6 prefixes longer then /64: are they possible in DOCSIS networks?

[Dmitry Cherkasov <doctorchd () gmail com>]

Hello everybody,

It is commonly agreed that /64 is maximal length for LANs because if
we use longer prefix we introduce conflict with stateless address
autoconfiguration (SLAAC) based on EUI-64 spec. But  SLAAC is not used
in DOCSIS networks. So there seems to be no objections to use smaller
networks per cable interfaces of CMTS. I was not able to find any
recommendations anywhere including Cable Labs specs for using
prefixes not greater then /64 in DOCSIS networks. Some tech from ISP
assumed that DHCPv6 server may generate interface ID part of IPv6
address similarly to EUI-64 so MAC address of the device can easily be
obtained from its IPv6 address, but this does not seem like convincing
argument. What do you think?


Dmitry Cherkasov