On Thu, Oct 26, 2017 at 2:47 PM, Jason Lixfeld <jason+na...@lixfeld.ca> wrote:
> Hi Bill, > > > On Oct 26, 2017, at 2:37 PM, William Herrin <b...@herrin.us> wrote: > > > > BGP routing is based on "distance". Distance in BGP is primarily > calculated as the number of ASNs in the AS Path. Prepends make a path more > distance, encouraging routers to choose a different path if one is > available. > > I understand how prepends fit in the context of best path selection, but > my question was more the difference between a customer signalling the ISP > to prepend their AS using a BGP community stamped to a prefix vs. the > customer prepending their own AS instead. > > blame shifting? avoiding instances where a third party filters: <ispasn> ?$ vs <ispasn> .*$ or just people's particular picadellos.
