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I looked up the public IPv6 addresses on google for two devices on my LAN, and the addresses are unique (only the first 64 bits match).

I thought that the router connected to the internet has a public IPv6 address that is assigned by the ISP. Then all of the devices on this router's LAN share this public address but have their own private address within the subnet to distinguish themselves. Can someone please clarify how this works? Thanks.

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IPv6 is designed to restore the original IP feature of end-to-end connectivity. Each host can have a globally unique address. This fixes the problems caused by NAT use in IPv4.

The RFC recommends that each person be assigned a /48 (65536 /64 subnets). Most ISPs actually will only give you something less like a /56. You can easily get a /48 by requesting it from your RIR.

Most home routers can't delegate more than a /64, but that is still over 18 quintillion addresses.

  • So if I were using IPv4, then I would see the same address when I look up the public IP of each device? – user3084963 Aug 15 '15 at 15:27
  • That depends. If your router is doing NAT, you will probably see only a single public address for all the hosts because you are using private addressing on the hosts. There is nothing (except a shortage of IPv4 addresses and your ISP's policies) preventing you from using unique, public IPv4 addresses for each host. IPv6 relieves the address shortage. – Ron Maupin Aug 15 '15 at 15:33

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