there is already some kind of tagging in IP: tos value. unfortunately, pf can not handle tos value for own purposes. from the other side, tos width is 4 bits only so it can not handle much of useful information (pf tags, for example). additionally, the way, the routers over the world can interpret tos value, is unpredictable.
How about if i use IP-V6? would that give me more space? comparible to space i have using pf-tagging? (in comparison to the 4 bits given by TOS)
IPv6 has a 20bit flow label. See http://zvon.org/tmRFC/RFC2460/Output/ sections 3, 6, and 9.
