v6 subnet size for DSL & leased line customers

Deepak Jain deepak at ai.net
Thu Dec 20 21:42:58 UTC 2007

> Why not a /48 for all? IPv6 address space is probably cheap enough that
> even just the time cost of dealing with the occasional justification
> for moving from a /56 to a /48 might be more expensive than just giving
> everybody a /48 from the outset. Then there's the op-ex cost of
> dealing with two end-site prefix lengths - not a big cost, but a
> constant additional cost none the less.

And let's not ignore the on-going cost of table-bloat. If you provide a 
/48 to everyone, in 5 years, those allocations may/may not look stupid. :)

Right now, we might say "wow, 256 subnets for a single end-user... 
hogwash!" and in years to come, "wow, only 256 subnets... what were we 

Its up to the ISP or LIR with minimum recommendations.
"RIRs/NIRs are not concerned about which address size an LIR/ISP 
actually assigns. Accordingly, RIRs/NIRs will not request the detailed
information on IPv6 user networks as they did in IPv4, except for the
cases described in Section 6.4.4 and for the purposes of measuring
utilization as defined in this document."



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