<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>swsieber</author><text>Playing Nintendo Switch online doesn&amp;#x27;t work if you&amp;#x27;re double NAT&amp;#x27;d unless you go through some router hoops. It seems small, but it&amp;#x27;s quite aggravating if you&amp;#x27;re not tech oriented like the majority of the people on this forum.</text><parent_chain><item><author>throw0101a</author><text>Because there are &amp;#x27;only&amp;#x27; 2^32, roughly four billion, IPv4 addresses. There are also over eight billion people on this planet, and many of them have multiple computers (smartphones, tablets, laptops, desktops, etc).&lt;p&gt;As a &amp;#x27;temporary&amp;#x27; measure, Network Address Translation (NAT) was introduced so people could get one public IPv4 address and have multiple machines on the Internet behind it.&lt;p&gt;The trade-off was the machines behind the NAT mechanism couldn&amp;#x27;t be reached from the Internet. This isn&amp;#x27;t a big deal for &lt;i&gt;most&lt;/i&gt; consumption-based computing (fetching mail, watching videos), but there are use cases where you want to be able to talk to the other system, so yet another set of technologies had to be invented to allow punching holes through NAT (UPnP, NAT-PMP, PCP, STUN).&lt;p&gt;But we&amp;#x27;re at the point in some place where there aren&amp;#x27;t even enough IPv4 addresses to give to ISP customers &lt;i&gt;even if&lt;/i&gt; they&amp;#x27;re using NAT. So you have a private IP address for your home system, and then your router gets a &lt;i&gt;private IP&lt;/i&gt; address on its &amp;quot;public&amp;quot; WAN connection, and you end up going &lt;i&gt;two layers&lt;/i&gt; of NAT. There is an entire segment of IPv4 addresses (100.64.0.0&amp;#x2F;10) reserved for telco use and doubel-NATing:&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Private_network#Dedicated_space_for_carrier-grade_NAT_deployment&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Private_network#Dedicated_spac...&lt;/a&gt;&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;IPv4_shared_address_space&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;IPv4_shared_address_space&lt;/a&gt;&lt;p&gt;We can continue this NAT-upon-NAT(-upon-NAT) silliness, or we can simply make the up-front investment and start pushing out IPv6 in more places. Your router still provides firewall protection, but reachability is a lot more straight-forward because the (potentially double) address translation goes away.&lt;p&gt;Edit: fix a bunch of typos.</text></item><item><author>distalx</author><text>ELI5: Why does IPv6 adoption matter? What would happen if these sites don&amp;#x27;t migrate to IPv6?</text></item><item><author>quaintdev</author><text>It&amp;#x27;s crazy that major web sites still do not support IPv6.&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.amazon.in&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.amazon.in&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.paytm.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.paytm.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;twitter.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;twitter.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.flipkart.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.flipkart.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.hotstar.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.hotstar.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.primevideo.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.primevideo.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.reddit.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.reddit.com&lt;/a&gt;&lt;p&gt;Edit: Removed google.co.in, the website[1] reported it that it does not support ipv6, Now I tried again and google is in green.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;ipv6-test.com&amp;#x2F;validate.php&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;ipv6-test.com&amp;#x2F;validate.php&lt;/a&gt;</text></item></parent_chain></comment><story><title>India is leading IPv6 migration with 61.67% adoption</title><url>https://www.aelius.com/njh/google-ipv6/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>WanderPanda</author><text>&amp;gt; NAT-upon-NAT(-upon-NAT)&lt;p&gt;But there is also a fundamental limit of 2^16 = 65536 concurrent connections, right?</text><parent_chain><item><author>throw0101a</author><text>Because there are &amp;#x27;only&amp;#x27; 2^32, roughly four billion, IPv4 addresses. There are also over eight billion people on this planet, and many of them have multiple computers (smartphones, tablets, laptops, desktops, etc).&lt;p&gt;As a &amp;#x27;temporary&amp;#x27; measure, Network Address Translation (NAT) was introduced so people could get one public IPv4 address and have multiple machines on the Internet behind it.&lt;p&gt;The trade-off was the machines behind the NAT mechanism couldn&amp;#x27;t be reached from the Internet. This isn&amp;#x27;t a big deal for &lt;i&gt;most&lt;/i&gt; consumption-based computing (fetching mail, watching videos), but there are use cases where you want to be able to talk to the other system, so yet another set of technologies had to be invented to allow punching holes through NAT (UPnP, NAT-PMP, PCP, STUN).&lt;p&gt;But we&amp;#x27;re at the point in some place where there aren&amp;#x27;t even enough IPv4 addresses to give to ISP customers &lt;i&gt;even if&lt;/i&gt; they&amp;#x27;re using NAT. So you have a private IP address for your home system, and then your router gets a &lt;i&gt;private IP&lt;/i&gt; address on its &amp;quot;public&amp;quot; WAN connection, and you end up going &lt;i&gt;two layers&lt;/i&gt; of NAT. There is an entire segment of IPv4 addresses (100.64.0.0&amp;#x2F;10) reserved for telco use and doubel-NATing:&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Private_network#Dedicated_space_for_carrier-grade_NAT_deployment&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Private_network#Dedicated_spac...&lt;/a&gt;&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;IPv4_shared_address_space&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;IPv4_shared_address_space&lt;/a&gt;&lt;p&gt;We can continue this NAT-upon-NAT(-upon-NAT) silliness, or we can simply make the up-front investment and start pushing out IPv6 in more places. Your router still provides firewall protection, but reachability is a lot more straight-forward because the (potentially double) address translation goes away.&lt;p&gt;Edit: fix a bunch of typos.</text></item><item><author>distalx</author><text>ELI5: Why does IPv6 adoption matter? What would happen if these sites don&amp;#x27;t migrate to IPv6?</text></item><item><author>quaintdev</author><text>It&amp;#x27;s crazy that major web sites still do not support IPv6.&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.amazon.in&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.amazon.in&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.paytm.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.paytm.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;twitter.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;twitter.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.flipkart.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.flipkart.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.hotstar.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.hotstar.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.primevideo.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.primevideo.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;news.ycombinator.com&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.reddit.com&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.reddit.com&lt;/a&gt;&lt;p&gt;Edit: Removed google.co.in, the website[1] reported it that it does not support ipv6, Now I tried again and google is in green.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;ipv6-test.com&amp;#x2F;validate.php&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;ipv6-test.com&amp;#x2F;validate.php&lt;/a&gt;</text></item></parent_chain></comment><story><title>India is leading IPv6 migration with 61.67% adoption</title><url>https://www.aelius.com/njh/google-ipv6/</url></story>