Problems with removing NAT from a network

[matthew at matthew.at (Matthew Kaufman)]

On 1/6/2011 5:48 PM, Owen DeLong wrote:
> Doesn't all of this become moot if Skype just develops a dual-stack capable client
> and servers?
>
Not really. Imagine the case where you're on IPv6 and you can only reach 
IPv4 via a NAT64, and there's no progress made on the detection problem. 
And your family member is on a Skype-enabled TV plugged into an 
IPv4-only ISP.

Now you can't get a direct media path between you, even though their ISP 
is giving them IPv4 and your ISP is *claiming* you can "still reach the 
IPv4 Internet".

Skype can still make this work by relaying, but in order to protect the 
relay machine's bandwidth it will rate-limit the traffic, and so your 
A/V experience will suffer. And that's assuming there's enough 
dual-stacked relays... if there aren't, it won't be possible to find a 
relay that they can reach over IPv4 and you can reach over IPv6 that has 
available bandwidth.

Matthew Kaufman