v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space (IPv6-MW)]

Patrick W. Gilmore patrick at ianai.net
Thu Feb 5 00:16:36 UTC 2009

On Feb 4, 2009, at 7:08 PM, Seth Mattinen wrote:
> Patrick W. Gilmore wrote:

>> Second, where did you get 4 users per /64?  Are you planning to hand
>> each cable modem a /64?
> That was the generally accepted subnet practice last time I had a
> discussion about it on the ipv6-ops list. I'm not an ISP, but I have a
> /48 and each subnet is a /64. Some devices will refuse to work if you
> subnet smaller than a /64. (Yes, poorly designed, etc.)

I Am Not An ISP either. :)

I guess I was thinking about v4 modems which do not get a subnet, just  
an IP address.  If we really are handing out a /64 to each DSL & Cable  
modem, then we may very well be recreating the same problem.

And before anyone says "there are 281474976710656 /48s!", just  
remember your history.  I was not there when v4 was spec'ed out, but I  
bet when someone said "four-point-two BILLION addresses", someone else  
said "no [email protected]#%'ing way we will EVER use THAT many...."


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