nanog mailing list archives

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


From: "Howard C. Berkowitz" <hcb () netcases net>
Date: Wed, 4 Feb 2009 19:38:34 -0500 (EST)

Patrick W. Gilmore wrote:
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 $@#%'ing way we will EVER use THAT many...."


Ah, but RFC 760, before 791, did assume "more than 253 networks? Nahhh..."



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