[AusNOG] SMH: "No room at the internet"

[Chris Edwards]

On 20/05/2010 2:08 PM, Matthew Moyle-Croft wrote:
> 
> On 20/05/2010, at 12:56 PM, Kevin Karp wrote:
> 
>> Hi David
>> 
>>> Most users need very few ports, ...
>> 
>> Very true, but even a few ports can hurt a lot.
> 
> For the ISP world we're not talking much overloading for CGNAT.   My
> view is that if you can achieve a 1:2 or 1:4 utilisation of IPv4
> addresses then that buys you a lot of time to get to a point where v4
> connectivity is just a "need to make things work occasionally".   In
> that kind of world each "service" can get, say, 16000 odd ports
> ((2^16)/4) and pretty much live an okay life providing that IPv6
> starts to take it's share of the load.   Even at a 1:8 ratio we're
> talking ~8000 ports/service.

Unless a service is directing all its connections to the same
address:port pair, you can reuse the same (externally visible) port for
multiple connections as far as I can see, meaning you're unlikely to
ever run out of ports with even a 1:4 ratio if implemented this way. You
could even share ports between services, but that might upset law
enforcement?

I'm eagerly awaiting a Melbourne ipv6 LNS for my Internode connection
though :-) Sadly (or perhaps happily) I don't think I'm missing enough
to justify the extra latency at the moment

Chris

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