I know this hasn't come up yet - but isn't it easier to implement fast-path tunneling than it is to implement fast-path tunneling with routing headers just because of the placement of the addressing information in the PDUs. Routing headers are fine for slow path signaling but probably not for fast-path operations. Encapsulation can be accomplished with simple pointer manipulation on packets. Routing headers require some block moves. Isn't that the real reason why this ID is here? Why don't people just come out and say it?
My2cents,
Glenn
