Firstly my apologies for the lateness of this review. This is a very well written draft, and can proceed as is. Useful clarity might be added to Section 4 (dataplane) by the inclusion of some figures. I say this as someone that finds it easier to take in information in that format, so that is a personal preference comment, the text is correct and technically sufficient. There is an intriguing piece of text in the dataplane section "While this may be useful in certain scenarios, it may provide unintended results in other scenarios." which I think might be usefully expanded to give at least one example of a use, and an unintended consequence. In the introduction it says: "In [RFC3107], this feature was controlled by a BGP Capability Code that has never been implemented, and is now essentially obsolete." which left me wondering whether there was the intention to formally deprecate the feature through the RFC system.