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Ownership of Routers on Both Ends of Transnational Links

Thank you so much for your insightful replies. We are asking the right

I checked the rest of them, they all seem to be /30 or /31s. jax-b1-link.telia.net telconet-ic-337544-jax-b1.c.telia.net las-bb1-link.telia.net
* chinaunicom-ic-302366-las-bb1.c.telia.net adm-b4-link.telia.net riot-ic-303251-adm-b4.c.telia.net sjo-b21-link.telia.net  <http://sjo-b21-link.telia.net>
* chinaunicom-ic-127288-sjo-b21.c.telia.net. 0.xe-1-2-1.GW7.LAX1.ALTER.NET chinaunicom-gw.customer.alter.net 0.xe-1-0-0.gw2.lax1.alter.net
*  chinaunicom-gw.customer.alter.net. ix-xe-0-3-3-0.tcore1.sqn-san-jose.as6453.net
*  ix-xe-8-2-5-0.tcore1.sqn-san-jose.as6453.net  ix-xe-2-1-3-0-0.tcore1.lvw-los-angeles.as6453.net
* ix-ae-2-611.tcore1.lvw-los-angeles.as6453.net

How about the two IPs(, that don't have a
reserve DNS name? Since they don't have any PTR records.

Pengxiong Zhu
Department of Computer Science and Engineering
University of California, Riverside

On Tue, Apr 16, 2019 at 1:50 PM Ross Tajvar <ross at tajvar.io> wrote:

> I think it's clear that the IPs belong to Telia, but I understood James's
> point to be that the router using the IP in question may belong to China
> Unicom. (I agree with that, I was not thinking clearly this morning.) As
> this is an interconnect link, one side must belong to Telia and the other
> to China Unicom. The question, then, is which side are we looking at? Well,
> first I want to know how big the subnet is. I assume either /30 or /31. So,
> I do a reverse DNS lookup on all the IPs in the surrounding /30 block:
> - sjo-b21-link.telia.net
> - chinaunicom-ic-341501-sjo-b21.c.telia.net
> - las-b24-link.telia.net
> - chinaunicom-ic-341499-las-b24.c.telia.net
> That looks like two /31s. Only one IP in each has the name of China Unicom
> in it, so that one is probably in use by China Unicom, and the other is
> probably in use by Telia.
> On Tue, Apr 16, 2019, 3:50 PM Christopher Morrow <morrowc.lists at gmail.com>
> wrote:
>> On Tue, Apr 16, 2019 at 10:59 AM James Jun <james.jun at towardex.com>
>> wrote:
>> > More likely, thease routers are China Unicom's routers in their US POP,
>> not managed by VZ/Telia.
>> > The /30s in this case are unmanaged IP transit hand-offs, coming in as
>> Nx10G or 100G.  When your
>> > IP transit provider assigns the /30, your router looks like it belongs
>> to your upstream, common
>> > mistake when interpreting traceroutes[1].
>> >
>> $ nslookup
>> name = sjo-b21-link.telia.net.
>> if you model (as james says) each interconnect as a /30 or /31 ...
>> look for the adjacent ip and see the PTR for that ip.
>> (the above is your first link example's peer ip)
>> > [1]: see Page 22 on
>> https://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute_N47_Sun.pdf
>> >
>> > James
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