Slashdot: UK ISP PlusNet Testing Carrier-Grade NAT Instead of IPv6

Lee Howard Lee at
Fri Jan 18 18:31:24 UTC 2013

On 1/18/13 1:03 PM, "Joe Maimon" <jmaimon at> wrote:

>Lee Howard wrote:
>> If an ISP is so close to running out of addresses that they need CGN,
>> let's say they have 1 year of addresses remaining.  Given how many ports
>> apps use, recommendations are running to 10:1 user:address (but I could
>> well imagine that increasing to 50:1).  That means that for every user
>> NAT, you get 1/10 of an address.
>> Example:  An 10,000-user ISP is growing at 10% annually.  They have
>> addresses left, so they implement CGN.  You say to assuming 90% of them
>> can be NATted, so next year, 100 get a unique IPv4 address, the other
>> share 90 addresses.  At 190 addresses per year, CGN bought you five
>> I think your 90% is high.  If it's 70%, you burn 370 per year.
>> That doesn't include the fact the increased support costs, or alienated
>> customer cancellations, or any of the stuff I talked about in TCO of
>> Lee
>2-5 years from a currently one year supply?
>Factor in the current base and growth for at least another decade is
>If it works for the new subscribers, it will work for the existing ones.

It is difficult to change an existing customer's service.  Good luck.

>Does anybody doubt that successful CGN deployment easily translates into
>many years more of v4?

Yes, I doubt it.  Although if you define "successful" as "many more years
of IPv4" my doubts vanish solipsistically.

>We understand that there are hosts of theoretical and practical impacts.
>What we do not yet know is how the public and providers at large will
>react or adapt to these impacts.
>If just the right balance of CGN negativity and resulting v6 adoption is
>the result, then we will all muddle through more or less ok.
>Otherwise we will be seeing either frantic v6 migration everywhere or
>even slower pace then what we have now.

Fear, uncertainty, doubt.  Possible frantic migration.
These sound bad to me.



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