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


From: Dmitry Cherkasov <doctorchd () gmail com>
Date: Tue, 29 Nov 2011 13:46:39 +0200

Owen,

Currently I research on IPv6 provisioning systems and I need to decide
whether the ability to use longer then /64 prefixes should be
supported in them or not. If we restrict user to using /64 per network
we need to have convincing reasons for this. Best practice and common
sense stand for using /64 but this may be not sufficient for some
people.

Dmitry Cherkasov



2011/11/28 Owen DeLong <owen () delong com>:
You can probably do it, but, what do you gain by doing so?

Owen

On Nov 28, 2011, at 3:37 AM, Dmitry Cherkasov wrote:

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



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