I seem to be getting easy documents of late. This document describes how to run BFD over LAGs. Multiple l2 links are combined into a larger l2 link for better throughput and load balancing and redundancy. >From the standpoint of /l3 these all appear to be a single interface. If you look at it funny and futz your tables so BFD gets to treat these interfaces as distinct, you can use BFD to make sure members of the LAG are up. If the universe valued good abstraction layers, entire civilizations would crumble in disgust every time you send one of these packets. However, it is a useful hack for performance and code re-use. The document claims that there are no new security considerations. As far as I can tell, that is true. I have no concerns.