[192102] in North American Network Operators' Group
Re: nested prefixes in Internet
daemon@ATHENA.MIT.EDU (Martin T)
Wed Oct 19 12:27:42 2016
X-Original-To: nanog@nanog.org
In-Reply-To: <49C83B6E-C0D5-44C0-A13C-7B55F5AF5254@delong.com>
From: Martin T <m4rtntns@gmail.com>
Date: Wed, 19 Oct 2016 19:27:37 +0300
To: Roy Engehausen <r.engehausen@gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
Hi,
I made a drawing of those two best solutions: http://i.imgur.com/7NQVgUH.pn=
g
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=E2=80=A6 There are myriad reasons that the /24 might not reach=
a network peered with ISP-A, including the possibility of being a downstre=
am customer of a network peered with or buying transit from ISP-A. In the l=
atter case, not an issue, since it=E2=80=99s paid transit, but in the forme=
r (peered, not transit), again, ISP-A is probably not super excited to carr=
y traffic that someone isn=E2=80=99t paying them to carry.
>>>
>>
>> But ISP-A is in fact being paid to carry the traffic. Supposedly ISP-B h=
as a paid transit relation to ISP-A. In the case the transit link is down I=
SP-A might have to transport the traffic through a less profitable link how=
ever.
>
> Which isn=E2=80=99t really in the agreement between ISP-B and ISP-A unles=
s it was specifically (and unusually) negotiated.
>
> Also, you=E2=80=99re assuming that the leased space came with a transit a=
greement. In many cases, address leases don=E2=80=99t, so consider the addi=
tional scenario where ISP-B leases addresses from ISP-A, but has transit co=
ntracts 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 th=
e transit link down. Yes I might have to transport something out of my netw=
ork through one of my transits, but outbound traffic is in fact free for us=
because we are heavy inbound loaded.
>
> Yes, but it doesn=E2=80=99t help if it also came in on a transit link. An=
y traffic you both receive and transmit on transit costs you money pretty m=
uch no matter who you are.
>
>
> Owen
>
