Comments inline > On Jul 26, 2020, at 12:50 PM, Robert Raszuk <rob...@raszuk.net> wrote: > > All, > > Happy to see this draft ! Have been struggling with explaining some of those > issues and lack of such BCPs was sort of implicit prove that it is all fine > to prepend at will. > > Said this it seems clear that putting aside cases of unnecessary use or use > by errors AS-PATH prepends we are still facing no Internet wide path > de-prefernecing in BGP being commonly used other then mangling AS-PATH. > > The point is that multihoming is common and if someone needs at least to try > to influence entrance to his domain AS-PATH prepend comes as low hanging > fruit. > > Longer prefix will not work when on both ASBRs a /24 is injected.. > > So let me ask a question here ... > > Have anyone tried to document that instead of doing AS-PATH prepend across > set of upstreams (for whatever valid reason that may be) the preferred > entrance should advertise the paths with IGP or EGP origin while the other > ASBRs (which would otherwise prepend N times) with INCOMPLETE ? BGP best path > should automatically across most implementations do the right path selection.
Offhand, I don’t know of anyone who has tried to document this. But why EGP origin? EGP is a Historic protocol that is rarely if ever used. IMO, although this technique could work, it is misleading. > Anyone see any issue with that ? If that works we could actually start to > strongly discourage use of AS-PATH prepending. > > If not maybe we should think about a new attribute along the lines of cost > community to be more widely used in a transitive manner and to have single > meaning to allow to deprefer a prefix originated by given AS across number of > ISP uplinks with a numeric value (just like MED or Local Pref are used > locally). IMO, this is a better idea. > Another question the draft talks about AS-PATH prepends by actual sources ... > well suffice to just take a look at Internet tables in few places to see that > even some transit operators prepend themselves to the original paths (also > already prepended). And yes I do have captures of those. > > Thx, > R. Regards, Greg _______________________________________________ GROW mailing list GROW@ietf.org https://www.ietf.org/mailman/listinfo/grow
