I recently noticed that my ISP doesn't like routing native SCTP traffic over the Internet, unless it's tunnelled through UDP. A bit of a pain, but I solved the issue by using tunelling.
This issue got me thinking - other than TCP and UDP, which transport layer protocols are (generally) allowed to be routed properly across the Internet, over IPv4? Is the "normal" policy to allow all forms of IPv4 traffic, regardless of the protocol?