pmeerw's blog

Sun, 21 Aug 2022

IPv6 tunnel adventures

Salzburg AG Cablelink sucks. After an upgrade of the cable modem (Technicolor CGA2121 to CGA4233, both crap), my Hurricane Electric ( IPv6 tunnel stopped working. It turned out that the new modem (likely) blocks all protocol 41 IP traffic (which is used for encapsulate IPv6 inside IPv4 packets). It's a prerequisite to use's tunnelbroker service.

Salzburg AG offered to set the modem into bridge mode, but then likely telephone service will not be available. What are the alternatives? There are other protocols used for tunneling, in particular wireguard, which is a modern protocol which passes traffic over UDP. Wireguard is supported by my Mikrotik router (ROS version 7 required), but not Let's look into other tunnelbroker services, such as route48 and route64.

              +-------------+        +--------------+
              |  Cablelink  |        |   Mikrotik   | <----> VLAN1 (
Uplink <----> |    modem    | <----> |    router    | <----> VLAN2 (
              | |        | |
              +-------------+        +--------------+

route48 worked immediately, there is a nice tutorial to configure an IPv6 tunnel with Mikrotik. They hand out a /48 which makes it easy to divide into subnets for local consumption.

route64 is similar, but here you have IPv6 addresses for the gateway, and a separate /56 subnet. So far, I could not get it to work, the remote gateway host tells me that "Destination unreachable: No route", hm.

posted at: 01:35 | path: /configuration | permanent link

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