In Denmark, FTTH is common. The fiber-providers each have an area that they connect. There is no overlap, unlike in the Netherlands where some households have multiple fibers sticking out of the pavement. These fiber-providers provide services for a few different ISP’s, some regional and some nationwide. These are the broadband options at my location from the “CheckYourNetwork” website, prepared by the Agency for Digitisation (Digitaliseringsstyrelsen).
My location is connected by EWII, a local energy company that also provides internet service. You have a “Fiberboks” somewhere in your house that terminates the fiber and provides an ethernet connection. I went with EWII for their internet service; not the cheapest one, but you get what you pay for.
Most providers give you the option of a fixed, static IPv4 address for 29 to 39 DKK per month extra. My 500/500 connection with fixed IP costs me 52 Euro/month. Our area is connected to the coax network as well, so there is also the option of internet via coax. But current DOCSIS will not provide me with 500MB upload.
I wanted to use my own router, since the one from EWII has very limited configuration options. Also the wiring options in my house dictated an access point separate from the router. A colleague advised me to go with either Unify Cloud Gateway or a Mikrotik router. I chose Mikrotik (E50UG) and as it turned out, that was the right choice for me.
With the Mikrotik router, IPv4 worked “out of the box” with the default factory installed configuration. Because multiple service providers share the same access-network, a VLAN is normally used on the “Fiberboks” ethernet port. But since EWII also provides the physical connection at my location, EWII’s “own” traffic is not VLANned.
IPv6 did not worked out of the box of course, so the learning and Google journey begins to collect info on the IPv6 setup used by EWII. Big advantage, I know the IPv6 delegated prefix (from the EWII provided router) and it’s fixed; static IPv4 also implies static IPv6 prefix as the reverse DNS lookup showed (2a00.8200.2176.0000.xxxx.xxxx.xxxx.xxxx.static6.ewii.dk).
The router WAN side is normally configured by DHCP and this also applies to IPv6. Since IPv4 uses NAT, there is only one address to provide, which is used on the router’s WAN port. Because of NAT, it does not matter what’s used on the LAN side. To avoid duplicate IP addresses, the LAN side uses a special private IP range that’s not used on the internet (defined in RFC1918). In general, with IPv6 the router does not use NAT. Given the vast IPv6 address space, there is no need to save on IP addresses. So now your provider needs to tell you which address range (network) to use on the LAN side. In IPv6 lingo, this process is called prefix delegation. You still need an IPv6 address for the router WAN port of course, just as with IPv4. Note that the WAN and LAN IPv6 networks can be completely different address ranges.
One improvement with IPv6 compared to IPv4 is automatic configuration. That’s all about link-local addresses and router advertisements (RA). With Apple devices on the LAN, RA is sufficient, no need for an IPv6 DHCP server. But how about the WAN side? With my provider EWII, the RA configured the WAN port and the default gateway. Then ping to an IPv6 address from the router just works. So that’s almost “out of the box”: I changed IPv6 -> Settings to Accept Router Advertisements.
DHCPv6 is used by most ISP’s to provide the prefix. This did not work with EWII. But since I know the prefix already, I just configured it manually on the router LAN port (with address ::1) and enabled “Advertise”. All clients now get a global IPv6 and the online IPv6 tests succeed. Job done? Nope…. After some time the IPv6 connectivity was just gone… Switched to provider router, all good. Switched back to Mikrotik, all good. Next day: no IPv6 connectivity. Tests then revealed that the IPv6 prefix network was not known on the internet anymore, i.e. no route to the network. Only explanation: the ISP WAN router keeps state based on DHCPv6 client requests. No DHCPv6 client requests (or renew) for some time and the prefix gets invalidated. So I must get the DHCPv6 client working…
Yes, that’s a cliff-hanger, to be continued here.