Current Consensus on IPv6 Customer Allocation Size

Tim Densmore tdensmore at
Wed Aug 1 21:17:20 CEST 2012

Hi Folks,

I have read through multiple threads regarding this issue (though most 
of them are years old), and know it may be a can of worms, but I need 
some insight into what people are actually doing in 2012. ARIN 
"suggests" a /48 for all customers or sites as far as I can tell, though 
apparently in the past they also had language including /56 assignments 
in some docs.  I'm trying to come up with a reasonable numbering plan 
that can accommodate /48 customer assignments from our /32.

Basically, here's how I'm looking at things in a nutshell.  We currently 
have 8 POPs that need subnets allocated, but obviously I want to leave 
room for future growth.  This leaves me with /36 or /37 per-POP (yes, I 
know that the idea of /37 might bother some folks) which would allow me 
16 or 32 POPs respectively.  Some POPs are obviously smaller than 
others, but I don't want to get into variable sized allocations 
per-POP.  Even with a /36 per-POP, when using /48, this allows me a 
maximum of 4096 allocations before having to add a second /36 to the 
same POP.  This is fine for business connections, but kind of dicey for 
residential services. Obviously we could go back to ARIN for another 
allocation if we end up in a bind down the road, but there is a real 
cost associated with changing designation from a "small" to "large" org 
(we actually qualify as a medium org, but nibble boundary allocations) 
that I'd prefer to avoid.

Is the current (again, 2012 - most threads and books that I have read 
are al least a few years old) consensus that a /48 per-residential-user 
really justified?  Opinions or pointers to current Fine Manuals to read 
would be most appreciated.



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