On Thu, 26 Oct 2017, Jason Lixfeld wrote:
Absolutely. I understand the "Prepend to Network blah” use case. The case I don’t get is where the ISP makes no distinction in their policy document about how the prepending of their own AS is applied to their upstream announcements, implying that it’s announced to everyone.
The "prepend to everybody" communities are usually implemented as "prepend to all peers", excluding customers, and for some variable definition of "all". YMMV, caveat emptor, et cetera -- in most cases you'll need to experiment. I've used "prepend to all peers" communities a few times to avoid saturating transit links that are being consolidated but still under contract, in order to keep the link viable and in use by the immediate neighbor and their customers, but otherwise make it less attractive to the rest of the world under normal conditions. -Rob