In the future, since every IP (IPv6 adress) is going to be global, we don't need to use NAT. So basically, why do I need a router on an IPv6-only global network?

Why not just replace my router with a switch? then every device can get an IP adress from my ISP and then they can connect to the internet?

  • Just because it can be global does not mean it should be global. You still need a router to support IPv4 devices.
    – Ramhound
    Jul 7 '14 at 16:51

Routers are for connecting networks. NAT is just one of the functions. If we are talking IPv6 only network, yes they provide end-to-end connection, but that doesn't mean your computer knows about every device on the Internet. You still need connection to your ISP which will route your requests.

  • But they can know the computer of my ISP:s gateway? Jul 7 '14 at 17:11
  • My computer can have the same routing table as my router? Jul 7 '14 at 17:12
  • Routers are also little computers, with special properties. If you can connect your PC directly to ISP and have at least 2 NIC (Network Interface Card) then yes, your computer can work as a router and have routing table for your network. You still have your subnet in IPv6 and everything outside of your own LAN has to be routed to your ISP.
    – phandox
    Jul 7 '14 at 17:17
  • So every computer on my LAN can't have an individual connection to my ISP? they can't "know" the way to my ISP? Jul 7 '14 at 17:20
  • There must be some connection to your ISP - usually you get 1 cable and then, you can connect it to anything. We use routers because they are then set as default gateway for computers in LAN and this router is the only one who knows the way to ISP (it's directly connected).
    – phandox
    Jul 7 '14 at 17:31
  • A router will provide security from many link local attacks.
  • Your ISP may not be willing to maintain per computer state such as DHCP leases, PPP connections, and bridge forwarding state.
  • Your ISP connection may be something other than Ethernet, such as PPP over ATM.

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