What's the point of prepend communities?
rwf at loonybin.net
Thu Oct 26 19:56:17 CST 2017
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
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.
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