Am 16.04.2014 13:08, schrieb Jeroen Massar:
More specifics are evil and give weird routing in various locations.
Not always. When Init7 started to propagate more specifics to it's four /19 and /18, about 2gig of inbound traffic switched from transit links to peering links. This is real money and IMHO a valid reason to propagate selectivly more specific prefixes (i.E. two /20 for one /19).
Massiv deaggregation however is indeed evil, and there are just too many networks out there which do it unconsciously in a very stupid way.
Init7 is filtering away more than 10000 more specific prefixes from transit. To explain this a bit further I'd like to point to a presentation I gave a while ago during NANOG 54.
https://www.nanog.org/meetings/nanog54/presentations/Monday/Kuenzler.pdf