John, I am determining technical requirements to IPv6 provisioning system for DOCSIS networks and I am deciding if it is worth to restrict user to use not less then /64 networks on cable interface. It is obvious that no true economy of IP addresses can be achieved with increasing prefix length above 64 bits.
As for using EUI-64, unlike random or sequential generation it provides predictable results that may be desired, e.g. for tracking some device migration between different networks. Dmitry Cherkasov 2011/11/29 Brzozowski, John <[email protected]>: > Dmitry, > > > You could consider the use of prefixes longer than the /64 on CMTS > interfaces, however, it is not clear to me why this would be done. > Further, most DHCPv6 implementations do not require that the generated > IPv6 address be eui-64 based. A randomized algorithm could also be used. > Another consideration is what happens after IPv6 is used for addressing > cable modems. What happens when you want to address CPE or CPE routers? > You are right back to /64 or shorter depending on the type of device being > provisioned. > > FWIW - we have found that there are distinct benefits to using IPv6 beyond > the amount of addresses that are available. The use of /64 is tightly > coupled with these benefits. > > Can you elaborate as to why one would want to or need to use prefixes > longer than /64? > > John > > On 11/28/11 6:37 AM, "Dmitry Cherkasov" <[email protected]> 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 >> >
