[arin-ppml] inevitability of NAT?

Benson Schliesser bensons at queuefull.net
Thu Feb 10 11:30:38 EST 2011

On Feb 10, 2011, at 10:05 AM, Jack Bates wrote:

> On 2/10/2011 9:42 AM, Benson Schliesser wrote:
>> In the meantime, until PCP is available, users should consider
>> turning off UPNP support in their gateway to make sure apps don't
>> rely on it when they're behind a CGN.
> User got a faulty DSL modem a few months back. uPNP wasn't enabled per the norm. User was unable to use some xbox functionality.
> The degree at which things are depending on uPNP has grown to making it almost mandatory. Turning it off is likely to lead to things breaking. In addition, no protocol is going to fix LSN well. I don't think any studies have really been done to see at what scale applications are currently using uPNP to (port forward, open firewall). This places practical limits on the number of people doing a certain thing while behind a single IP.

My opinion, to some extent, is that in the coming years: clients that require IPv4 but don't work well with NAT should expect to break.  On the other hand, clients with IPv6 support should experience an improved experience.

That said, UPNP (and NAT-PMP etc) just don't scale to the carrier scope.  PCP is coming, and clients should expect to migrate if they need IPv4 NAT support.  PCP will also support IPv6 pinholes (i.e. control of security in IPv6-enabled CPE), so clients should migrate regardless.

By the way, one of the PCP working group chairs is Dave Thaler from Microsoft (maker of Xbox).


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