Re: nested prefixes in Internet

[Owen DeLong <owen () delong com>]

Assuming that there is a PNI A<->C assumes facts not in evidence.

Owen

> On Oct 19, 2016, at 11:27 AM, Martin T <m4rtntns () gmail com> 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 <owen () delong com> wrote:
> > > On Oct 10, 2016, at 14:59 , Baldur Norddahl <baldur.norddahl () gmail com> 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