Florian: as I told in my initial e-mail, ISP-B is multi-homed, i.e connected to ISP-A(who leases the /24 to ISP-B from their /19 block) and also to ISP-C. ISP-B wants to announce this /24 both to ISP-A and ISP-C. That's the reason why either solution 1 or 2 in my initial e-mail is needed.
However, I would like to hear from Roy and Mel why do they prefer a third option where ISP A announces the /19 and the /24 while ISP B does just the /24. thanks, Martin On Wed, Oct 5, 2016 at 11:50 PM, Florian Weimer <[email protected]> wrote: > * Martin T.: > >> Florian: >> >>> Are the autonomous systems for the /19 and /24 connected directly? >> >> Yes they are. > > Then deaggregation really isn't necessary at all. > >>> (1) can be better from B's perspective because it prevents certain >>> routing table optimizations (due to the lack of the covering prefix) >> >> What kind of routing table optimizations are possible if covering /19 >> prefix is also present in global routing table? > > The /24 prefix could arguably be dropped and ignored for routing > decisions.
