<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>aexaey</author><text>The statement about IPv6 [internet] having 2^128 addresses is completely and utterly untrue, in the same way as it would be untrue to claim that IPv4 [internet] have 2^48 TCP ports.&lt;p&gt;What IPv6 have address-space-wise, is 2^64 subnets, out of which 2^61 is actually allocated to be routable over public internet.&lt;p&gt;Then comes granularity of &amp;#x2F;48 allocations (= 2^16 subnets) to end users and &amp;#x2F;32 allocations (= 2^32 subnets) to ISPs. That gives just 2^45 end users and 2^29 ISPs at best. In practice, if handing a user a &amp;#x2F;48 would become a common practice, all medium and large IPSs would start accumulating multiple &amp;#x2F;32s, then routing concerns would come back, and largest ISPs will start aggregating to &amp;#x2F;28s or &amp;#x2F;24s or whatnot.&lt;p&gt;That is still a whole lot of addresses (and IPv4 still looks laughably small in comparison), but actual, practical numbers are way, way lower then &amp;quot;340 undecillion&amp;quot; marketing figure being plastered all over the place.</text><parent_chain><item><author>msbarnett</author><text>&amp;gt; What am I missing?&lt;p&gt;A few things.&lt;p&gt;There&amp;#x27;s only 4,294,967,296 addresses in IPv4, so if you hand out giant blocks, you run out quite fast, whereas with 340,282,366,920,938,463,463,374,607,431,768,211,456 you could hand out huge IPv4 &amp;#x2F;8 sized blocks from now until the heat death of the sun if you wanted to.&lt;p&gt;But there&amp;#x27;s more to it than that. Right now only 1&amp;#x2F;8th of the IPv6 address space is &amp;quot;assigned to the internet&amp;quot;, so there&amp;#x27;s effectively 7&amp;#x2F;8ths being held in reserve for the foreseable future -- this is partially to accommodate realistic router memory limits in the near term. IPv6 also has a more efficient hierarchical routing scheme than CIDR (which was kind of bolted on to IPv4 after-the-fact), which helps keep router tables from consuming terabytes of RAM. And IPv6 is designed to be more easily renumberable when we &lt;i&gt;do&lt;/i&gt; make mistakes with assignments, with a clear separation between subnet prefix all that requires is changing the routing prefix.&lt;p&gt;At the end of the day, with 340 trillion trillion trillion addresses, handing out too many isn&amp;#x27;t ever going to be a big worry in the foreseeable lifetime of...anything, really.</text></item><item><author>thaumasiotes</author><text>I have a hard time seeing how IPv6 solves this problem. If we allocate them all individually, we have a world-shattering routing table problem. If we allocate them in gargantuan blocks, we have the same problem we have now with IPv4 -- we can&amp;#x27;t reallocate because routing becomes an impossible task. What am I missing? We&amp;#x27;re certainly not going to get the allocation right by doing it all at the beginning.</text></item><item><author>msbarnett</author><text>Because address allocation is inefficient and it is impractical to address this inefficiency in IPv4.&lt;p&gt;ARIN is out but your ISP has extras. Why doesn&amp;#x27;t your ISP sell its extras, since a scarce resource should have monetary value?&lt;p&gt;&lt;i&gt;Routing tables&lt;/i&gt;.&lt;p&gt;Selling individual IPs off piecemeal isn&amp;#x27;t practical because routers simply do not have enough RAM to handle the enormous routing tables that would resultantly be necessary in order for packets to find their destinations.</text></item><item><author>lordnacho</author><text>If IP addresses are scarce, why does it not seem to cost me anything to get one? I&amp;#x27;ve had a bunch of online servers that came with a static IP, and an ISP service that came with one, at various times. It seldom seemed to be explicitly priced, and when it was the price was not really something worth considering.</text></item></parent_chain></comment><story><title>ARIN Finally Runs Out of IPv4 Addresses</title><url>http://www.networkworld.com/article/2985340/ipv6/arin-finally-runs-out-of-ipv4-addresses.html</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>Sophira</author><text>The fact that only 1&amp;#x2F;8th is assigned to &amp;quot;the Internet&amp;quot; right now is worrying. After all, we know how that worked out with the 240.0.0.0&amp;#x2F;4 range in IPv4 - it was reserved for future use, but was never able to be used because by the time it would have been useful, everything classed it as non-routable. It&amp;#x27;s a huge swath of addresses that just can&amp;#x27;t be used.</text><parent_chain><item><author>msbarnett</author><text>&amp;gt; What am I missing?&lt;p&gt;A few things.&lt;p&gt;There&amp;#x27;s only 4,294,967,296 addresses in IPv4, so if you hand out giant blocks, you run out quite fast, whereas with 340,282,366,920,938,463,463,374,607,431,768,211,456 you could hand out huge IPv4 &amp;#x2F;8 sized blocks from now until the heat death of the sun if you wanted to.&lt;p&gt;But there&amp;#x27;s more to it than that. Right now only 1&amp;#x2F;8th of the IPv6 address space is &amp;quot;assigned to the internet&amp;quot;, so there&amp;#x27;s effectively 7&amp;#x2F;8ths being held in reserve for the foreseable future -- this is partially to accommodate realistic router memory limits in the near term. IPv6 also has a more efficient hierarchical routing scheme than CIDR (which was kind of bolted on to IPv4 after-the-fact), which helps keep router tables from consuming terabytes of RAM. And IPv6 is designed to be more easily renumberable when we &lt;i&gt;do&lt;/i&gt; make mistakes with assignments, with a clear separation between subnet prefix all that requires is changing the routing prefix.&lt;p&gt;At the end of the day, with 340 trillion trillion trillion addresses, handing out too many isn&amp;#x27;t ever going to be a big worry in the foreseeable lifetime of...anything, really.</text></item><item><author>thaumasiotes</author><text>I have a hard time seeing how IPv6 solves this problem. If we allocate them all individually, we have a world-shattering routing table problem. If we allocate them in gargantuan blocks, we have the same problem we have now with IPv4 -- we can&amp;#x27;t reallocate because routing becomes an impossible task. What am I missing? We&amp;#x27;re certainly not going to get the allocation right by doing it all at the beginning.</text></item><item><author>msbarnett</author><text>Because address allocation is inefficient and it is impractical to address this inefficiency in IPv4.&lt;p&gt;ARIN is out but your ISP has extras. Why doesn&amp;#x27;t your ISP sell its extras, since a scarce resource should have monetary value?&lt;p&gt;&lt;i&gt;Routing tables&lt;/i&gt;.&lt;p&gt;Selling individual IPs off piecemeal isn&amp;#x27;t practical because routers simply do not have enough RAM to handle the enormous routing tables that would resultantly be necessary in order for packets to find their destinations.</text></item><item><author>lordnacho</author><text>If IP addresses are scarce, why does it not seem to cost me anything to get one? I&amp;#x27;ve had a bunch of online servers that came with a static IP, and an ISP service that came with one, at various times. It seldom seemed to be explicitly priced, and when it was the price was not really something worth considering.</text></item></parent_chain></comment><story><title>ARIN Finally Runs Out of IPv4 Addresses</title><url>http://www.networkworld.com/article/2985340/ipv6/arin-finally-runs-out-of-ipv4-addresses.html</url></story>