I’m working on updating the BGP communities that are processed and used in my routers and I was interested as to what some of the common BGP communities that I might want to implement parsing for might be.
As I understand it, it is somewhat required that no export, no advertise and no export subconfed are implemented. I believe that there is also a no peer option which asks that a prefix not be announced over a peering relationship, only transit and downstream.
I do have my own informational prefixes for source location and peering vs transit prefixes so it would not be a stretch to add a version to allow for restrictions on where a prefix is announced and possibly prepending as well. I am aware that action communities exist for blackhole and setting of local preference but I can not find a consensus as to what those communities may be.