6to4 tunnel on a CRS109-8G-1S-2HnD

Hello everybody,

I’m having a weird problem setting up a 6rd tunnel at two locations.
On the smaller router I’m unable to keep the tunnel running while the very same setting is working as expected on a CRS125-24G-1S.

The interface is up and running.
A soon as I enable the default IPv6 route, I can sucessfully ping or traceroute for some time.
When I try to access a web page (eg ipv6.google.com), I may sucessfully connect at first.
But then suddenly the tunnel stalls. I can still send out pings but there’s no answer.
When I disable the default route, wait for some time and the re-enable it, i can sucessfully ping again until I try to transfer real payload.

I don’t have any idea about the cause and how to fix it.

The installations at the two locations are almost identical:

  • The provider is the same
  • the router is the same, running the same firmware version (Fritzbox 7490, OS 6.83)
  • the router’s IPV6 is off
  • the CRS is plugged on the same port of the router
  • the ROS is the same: 6.39.2

The only difference I see: the CRS109 uses a bridge while on the CRS125 there’s non by default.