Hi All!
I'm trying to get a feeling for how often ISPs announce a prefix from
different origin ASes intentionally.... (and why...)
I asked this question on my peering survey (*grin*), but I thought i'd hit
a wider audience...
Thanks.
-abha 
Abha,
One of the origins 
of inconsistent routes is improper multihoming --
a network is multihomed but no public ASN is assigned to it; some private
ASN is used and stripped off (by remove-private-as) at the edges of
the both (or many) ISPs, which results in multiple origin ASs for the
network prefix. I don't know how intentional this practice is, though
The question about how bad inconsistent routes are was also addressed
on this list.
Hi Dima...
One of the origins
of inconsistent routes is improper multihoming --
a network is multihomed but no public ASN is assigned to it; some private
ASN is used and stripped off (by remove-private-as) at the edges of
the both (or many) ISPs, which results in multiple origin ASs for the
network prefix. I don't know how intentional this practice is, though
Yeah. I know about that origin of inconsistent ASes. I'm more curious
about other creative occurences...
Thanks!
-abha 
Yeah. I know about that origin of inconsistent ASes. I'm more
curious about other creative occurences...
Some Exchange Point LANs don't have a well-defined origin AS, so if
multiple ISPs want to provide transit to the LAN, they'll announce it
from their respective AS and it will show up under multiple origins.
198.32.162.0/24 (Oregon-IX) and 194.42.48.0/24 (TIX Zurich) are two
examples of this.
Some Exchange Point LANs don't have a well-defined origin AS
as they are layer two LANs, this is reassuring. <grin>
randy