What protocol works on all layers of OSI?

None that I can think of. After all, one of the purposes of the OSI was to separate activities into layers so that applications like SMTP and HTTP are on top and others like TCP and UDP are more toward the middle. Wikipedia actually has a nice graphic that shows where some of the various layers are situated: Wikipedia Wikipedia's OSI model. Or you can read more by checking out the series of articles I wrote about the OSI model that can be found on SearchNetworking.com: OSI -- Securing the stack.