Current Consensus on IPv6 Customer Allocation Size

Tim Densmore tdensmore at
Thu Aug 2 18:29:55 CEST 2012

On 8/2/2012 6:56 AM, Daniel Roesen wrote:
> There is a big disconnect between real needs and policy for certain
> larger scale residential ISPs today, if you actually want to leverage
> operational advantages of IPv6 (read: having more bits for nice
> addressing and aggregation schemes).

Hi Daniel,

This point really hit the nail on the head (though we'er certainly not 
"larger scale"), and is really the main reason for my concern. BCP seems 
to dictate that we subnet at nibble boundaries and assign the smallest 
POP the same block size as the largest.  This is obviously an 
inefficient use of resources, but it does make for a much cleaner and 
more easily understood routing table.  It seems unlikely that I'll be 
able to summarize in IGP shorter than /40s in any case (based on current 
network topology), and I've read some arguments that this is a good 
reason to simply use /40 as a starting point, since it also allows for 
fewer idle subnets at smaller POPs and does away with my concern that 
I'd eventually run out of /48s in some POPs.  I'd rather follow the /32 
=> /36 => /40 scheme for my core/agg network, though.  Still mulling it 

Thanks for your input!


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