nanog mailing list archives
Re: What's the point of prepend communities?
From: Rob Foehl <rwf () loonybin net>
Date: Thu, 26 Oct 2017 15:56:17 -0400 (EDT)
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
Current thread:
- What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? Christopher Morrow (Oct 26)
- Re: What's the point of prepend communities? Job Snijders (Oct 26)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? Rob Foehl (Oct 28)
- Re: What's the point of prepend communities? Jason Lixfeld (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- RE: What's the point of prepend communities? Naslund, Steve (Oct 26)
- Re: What's the point of prepend communities? William Herrin (Oct 26)
- Re: What's the point of prepend communities? Brett Frankenberger (Oct 26)
- Re: What's the point of prepend communities? Steve Dodd (Oct 28)
- Re: What's the point of prepend communities? Leo Bicknell (Oct 26)
- Re: What's the point of prepend communities? Clinton Work (Oct 26)
- RE: What's the point of prepend communities? Naslund, Steve (Oct 26)
- Re: What's the point of prepend communities? Leo Bicknell (Oct 30)
- Re: What's the point of prepend communities? Michael Hallgren (Oct 30)