Hi,
our announcement on nanog a few months ago of experiments involving BGP updates containing large AS-sets [1] caused a few flames. Now we have an in-depth document with results on the subject and would like to explain what we intended to do.
We have presented our techniques at RIPE 50, and there is a Web page on the project, with links to the full report and the slides, up at:
http://www.dia.uniroma3.it/~compunet/bgp-probing/
What follows is a brief summary of what we do, why we believe it is safe, and why it shouldn't cause problems to current operational practices. For more details, see the presentation and the report.
We will be happy to answer any further questions you might have.
Regards,
Lorenzo Colitti
Thus, to stop its announcement from being propagated by ASes 1, 2, and
3, an AS (say AS12654) might announce one of its prefixes with an
AS-path of 12654 {1,2,3}.
won't that prevent 12654's announcements from being received by, as
opposed to propagated by, 1, 2, and 3?
randy
Randy Bush wrote:
Thus, to stop its announcement from being propagated by ASes 1, 2, and 3, an AS (say AS12654) might announce one of its prefixes with an AS-path of 12654 {1,2,3}.
won't that prevent 12654's announcements from being received by, as
opposed to propagated by, 1, 2, and 3?
More or less. Technically, unless sender-side loop detection is used, the routers in 1,2 and 3 will receive the announcement, but discard it because it contains the local AS. However, the path will not be one of the candidates for route selection, so it will probably not appear in the output of a query for the prefix, which amounts to much the same.
Regards,
Lorenzo