Why does my ISP sometimes give one IPv6 and another with a different subnet?

Comments

• hades@feddit.uk ⁨1⁩ ⁨week⁩ ago

  One is probably link local the other is global, that’s pretty normal. en.wikipedia.org/wiki/IPv6_address#Address_Scopes

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  • tdTrX@lemmy.ml ⁨1⁩ ⁨week⁩ ago

    one my openwrt router WAN IPv6 shows 2 IPs. IPv4 does get linklocal though

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    • Zikeji@programming.dev ⁨1⁩ ⁨week⁩ ago

      If your ISP is doing to right IPv6 should be setup for SLAAC, in which case they would give you an entire /64. I don’t use OpenWRT, but I assume it’s showing you the IPv6 /64 for reference, and the /128 of the router in case you need to hit the router using it? If it’s SLAAC your client devices should be getting two IPv6 addresses as well. One is for privacy, that’s the one websites will see when you connect but can’t be hit, and the other is the one you would use to reach your computer from another device.

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• just_another_person@lemmy.world ⁨1⁩ ⁨week⁩ ago

  [deleted]

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  • tdTrX@lemmy.ml ⁨1⁩ ⁨week⁩ ago

    How can I tell if IPv6 is CGNATed ?

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    • cmnybo@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

      CGNAT is a nasty hack to work around the shortage of IPv4 addresses. It’s not used with IPv6.

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    • Mondez@lemdro.id ⁨1⁩ ⁨week⁩ ago

      IPv6 should never be behind NAT which is a hack to extend the address space of Ipv4.

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    • just_another_person@lemmy.world ⁨1⁩ ⁨week⁩ ago

      It all is if you’re getting both. You’re sharing IPs with many different devices at the same time. That’s how it works.

      Read up on it.

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• undefined@lemmy.hogru.ch ⁨1⁩ ⁨week⁩ ago

  Are both subnets public?

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  • tdTrX@lemmy.ml ⁨1⁩ ⁨week⁩ ago

    one is 128 and other is 64

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    • Zikeji@programming.dev ⁨1⁩ ⁨week⁩ ago

      Ah - yeah the /128 is what the ISP used to route traffic to your router. I believe that’s IPv6 PD (prefix delegation) - the router uses DHCPv6, gets given that /128 it’ll use for the ISP, then the ISP delegates the /64 (or other sizes) to the router.

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• thelittleblackbird@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Are both of them ula addresses? (both of them starting with 2). If they are not the same then the ISP is providing an internal unique address for isp internal configurations.

  If so, are they having the same network? ( The first 48 bits) if not, then is probably a miss configuration but probably in their side. But with no practical effects. You could ignore it.

  If yes again, then it is a miss configuration and it shouldn’t happen, but this time it could be in your side, check that the dhcpv6 daemon doesn’t try to give an ipv6 address To your Wan port

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