Assuming that there is a PNI A<->C assumes facts not in evidence. Owen
> On Oct 19, 2016, at 11:27 AM, Martin T <[email protected]> wrote: > > Hi, > > I made a drawing of those two best solutions: http://i.imgur.com/7NQVgUH.png > > As much as I understand, both solutions require no special changes > from "ISP C". Only advantage of solution B over solution A, that I can > see, is that at the time when link between "ISP C" and "ISP B" is up, > the traffic from Internet towards "ISP B" prefers the "ISP C" > connection. > > > In case the link between "ISP A" and "ISP B" goes down, then traffic > from "ISP A" addressed to this /24 will use a private peering link > between "ISP A" and "ISP C" so the transit costs are not an issue. > > > thanks, > Martin > > On Wed, Oct 12, 2016 at 1:58 AM, Owen DeLong <[email protected]> wrote: >> >>> On Oct 10, 2016, at 14:59 , Baldur Norddahl <[email protected]> >>> wrote: >>> >>> >>> >>> Den 10/10/2016 kl. 22.27 skrev Owen DeLong: >>>> Not true… There are myriad reasons that the /24 might not reach a network >>>> peered with ISP-A, including the possibility of being a downstream >>>> customer of a network peered with or buying transit from ISP-A. In the >>>> latter case, not an issue, since it’s paid transit, but in the former >>>> (peered, not transit), again, ISP-A is probably not super excited to carry >>>> traffic that someone isn’t paying them to carry. >>>> >>> >>> But ISP-A is in fact being paid to carry the traffic. Supposedly ISP-B has >>> a paid transit relation to ISP-A. In the case the transit link is down >>> ISP-A might have to transport the traffic through a less profitable link >>> however. >> >> Which isn’t really in the agreement between ISP-B and ISP-A unless it was >> specifically (and unusually) negotiated. >> >> Also, you’re assuming that the leased space came with a transit agreement. >> In many cases, address leases don’t, so consider the additional scenario >> where ISP-B leases addresses from ISP-A, but has transit contracts with >> ISP-C and ISP-D but no connection at all to ISP-A. >> >>> I know that if ISP-A was my network I would be making money even with the >>> transit link down. Yes I might have to transport something out of my >>> network through one of my transits, but outbound traffic is in fact free >>> for us because we are heavy inbound loaded. >> >> Yes, but it doesn’t help if it also came in on a transit link. Any traffic >> you both receive and transmit on transit costs you money pretty much no >> matter who you are. >> >> >> Owen >>
