I'm curious if these routers / gateways that block IPIP (protocol 4)
traffic might successfully forward GRE (protocol 47)?
GRE is significantly more modern and hopefully, more "allowed" on some
of these networks. If it's indeed more "available", I wonder what would
be the climate to see if we could get everyone to switch from IPIP to
GRE. I imaging that Linux-bsaed systems (and Mikrotik, Cisco, etc)
platforms be configured to act as a protocol bridge for any legacy
applications running on it. The biggest challenge would be for folks
that are using some legacy NOS applications that only support IPIP.
Thoughts?
--David
KI6ZHD