The one at the link you gave me. It doesn't list any products at all and says that protocol draft is expired.
Scroll down and check out some of the neato commercial products.
Then tell me you live in a free country.
By the way, some common LI protocols are X1_1, X2P, and X3P. These are XML-based. Funny how they do not show up in the product documentation. No need for the sheeple to know how easy it is for Big Brother to listen in.