[Starlink] Info on IP country ranges

Alexandre Petrescu alexandre.petrescu at gmail.com
Wed Dec 13 05:33:45 EST 2023 

Le 12/12/2023 à 11:50, Sebastian Moeller a écrit :
> Hi Steven,
>
>
>
>> On Dec 12, 2023, at 11:33, Steven via Starlink <starlink at lists.bufferbloat.net> wrote:
>>
>> Hi Alex,
>>
>> Thank you for the further detail, my apologies if I misunderstand your line of inquiry. I had interpreted it to mean that you were still not convinced it was native from the perspective of the end-user visible components.
>>
>> You are right that there may be some IPv6-in-IPv4 encapsulation occurring within the Starlink network that is undetectable to end-users. That said I would be surprised if that was the case but as you highlight can't say conclusively, not having inside knowledge as to their architecture.
> 	One easy thing to check would be MTU/MSS to arbitrary internet end points, as any encapsulation typically takes up some space and not every operator id courteous enough to enlarge the tunnel MTU such that the inner internet visible effective MTU is 1500 bytes. Sure, not a guarantee but at least an easy to check hint.
>
>> If it helps, the latency and throughput I have measured of IPv4 vs IPv6 on Starlink is comparable, so if encapsulation is occurring it doesn't appear to be having a noticeable performance impact.
> 	Or both IPv6 and Iv4 user packets go through the same type of tunnel set-up to get to their home-base station?

Indeed, if tunnelling is used within the starlink network (like GTP a 
3GPP network) that would presumably encapsulate both IPv4 and IPv6.  A 
tunnel elimination technique within the starlink network would 
presumably reduce the latency both of IPv4 user packets and of IPv6 user 
packets.

There is also the mobility aspect of the tunnels.

A tunnel within 3GPP network (GTP) is used, among other reasons, to 
support mobility.  The 'mobility', among some interpretations, is to 
maintain a constant IP address for a moving end user.

Surprisingly, the URL 
https://support.starlink.com/?topic=1192f3ef-2a17-31d9-261a-a59d215629f4 
explains that that kind of mobility is not supported in starlink, i.e. 
the end user might get another IP address if going to some other area.  
It is surprising in that in other starlink.com URLs they offer starlink 
service for automobiles, and these typically move a lot.  Maybe the 
starlink-connected automobiles do change their IP addresses a lot, but 
the end users dont care that much.

To support mobility within a starlink network - maintain constant all IP 
addresses in a car - maybe one would try the DHCPv6 CONFIRM message to 
try to maintain the same allocated /56 but it another area.  Maybe the 
starlink DHCPv6-PD server will satisfy that CONFIRM, or maybe not.

Or maybe there is a need of some other protocol in starlink, or in user 
equipment connected to starlink (Dishy, third party router), to offer 
that mobility.  But without adding new latency, of course.

(this mobility aspect is on topic of the IP country ranges - 
cross-border areas would ideally not break connectivity).

Alex

>
> Regards
> 	Sebastian
>
> P.S.: All wild speculation, feel free to ignore ;)
>
>
>> Regards,
>> Steven
>>
>> On Tue, 12 Dec 2023, at 9:22 PM, Alexandre Petrescu wrote:
>>> Le 12/12/2023 à 03:43, Steven a écrit :
>>>> Thanks for this reference that explicitly states it is IPv6 native.
>>>>
>>>> https://support.starlink.com/?topic=1192f3ef-2a17-31d9-261a-a59d215629f4 is another Starlink resource that confirms that a /56 is provided. This one doesn't explicitly mention native, but as mentioned I am confident it is.
>>> Thanks for the pointer.  It clarifies indeed almost all my questions
>>> about IPv6 to starlink end users.  It is clear about that /56 to end
>>> users.  You also provided confirmation that is with DHCPv6-PD, and not
>>> tunnelbroker nor 6to4.  This is already very good.
>>>
>>> What I further asked (is IPv6 encapsulated in IPv4?) might probably not
>>> be within the reach of non-starlink administrators, not visible to
>>> starlink end users.  Sorry for having given the impression that I might
>>> doubt the skilfullness.
>>>
>>> For example, in 3GPP networks, it is also said, and generally agreed by
>>> very skilled persons, that almost all IPv6 is provided as native IPv6.
>>> In that context, it means that the packets from smartphone to a core
>>> network entity are not encapsulated in IPv4. But, it is also agreed that
>>> within that core network, that IPv6 is encapsulated in the GTP protocol,
>>> which is an UDP/IPv4 protocol. This encapsulation of IPv6 in IPv4 is
>>> invisible to end users, even if the encapsulation is there.
>>>
>>> For 3GPP, the use of GTP is very much dedicated to supporting mobility -
>>> a user keeps a same IP address while changing base stations and S-GWs or
>>> SGSNs.  In starlink, on the contrary, it is probably not the case that
>>> the GTP protocol is used for mobility (I dont know?), because starlink
>>> says that the IP address might change during mobility (that URL you
>>> point to says "Our system is dynamic where moving the Starlink to
>>> another location [...] may cause the public IP to change."); so maybe
>>> IPv6 is not encapped in UDPv4.  Still, another role of GTP in 3GPP is
>>> that of providing a notion of 'circuit', for needs such as AAA: one such
>>> 'circuit' is associated to one authenticated and billed user.  And
>>> starlink users _are_ authenticated and billed, too.  Thus, one might
>>> wonder what other than 3GPP's GTP protocol is starlink using to provide
>>> that notion of 'circuit'-per-user.  Maybe that starlink-circuit protocol
>>> is using tunnels, and that tunnel might be an IPv4 tunnel; it might also
>>> be an IPv6 tunnel.  Maybe it is using MPLS. Maybe something else.
>>>
>>> It is  worth considering about standards work, interoperability with
>>> others, a probable NTN-TN convergence, and similar.
>>>
>>> Alex
>>>
>>>> Cheers,
>>>> Steven
>>>>
>>>> On Tue, 12 Dec 2023, at 1:29 PM, J Pan wrote:
>>>>> yes. https://starlink-enterprise-guide.readme.io/docs/ip-addresses
>>>>> "Starlink is IPv6 native network. Using IPv6 is more flexible and
>>>>> future-proof." starlink has greatly improved tech docs
>>>>> --
>>>>> J Pan, UVic CSc, ECS566, 250-472-5796 (NO VM), Pan at UVic.CA, Web.UVic.CA/~pan
>>>>>
>>>>> On Mon, Dec 11, 2023 at 5:10 PM Steven Honson via Starlink
>>>>> <starlink at lists.bufferbloat.net> wrote:
>>>>>> Hi Alex,
>>>>>>
>>>>>> As an experienced network engineer with extensive experience with IPv6, I'm confident this is native IPv6.
>>>>>>
>>>>>> Cheers,
>>>>>> Steven
>>>>>>
>>>>>> On Tue, 12 Dec 2023, at 2:30 AM, Alexandre Petrescu wrote:
>>>>>>> Steven,
>>>>>>>
>>>>>>> Thanks for the clarifications. It is indeed very advantageous to use
>>>>>>> DHCPv6-PD from a Client in home to starlink Server, and obtain a /56.
>>>>>>>
>>>>>>> But to be native IPv6, it would need the IPv6 packets to travel natively
>>>>>>> (sit directly on the link layer) between home and starlink network.  If
>>>>>>> these IPv6 packets are encapsulate in IPv4, then there would be a risk
>>>>>>> of additional latency compared to v4.
>>>>>>>
>>>>>>> A possible way to find out whether it's IPv6 native (and hence no
>>>>>>> additional latency) is to browse speedtest.net from an IPv4-only client
>>>>>>> vs from an IPv6-only client.  An IPv6-only Windows client can be made by
>>>>>>> unchecking the IPv4 box in interface Properties window.
>>>>>>>
>>>>>>> Ideally, if it is IPv6 native, the latency reported by speedtest.net is
>>>>>>> approximatively the same on IPv4 vs on IPv6 (sometimes the IPv6 latency
>>>>>>> is even lower than on IPv4).  If the latency reported on IPv6 is higher
>>>>>>> than on IPv4 it could be for many reasons, and one of them could be that
>>>>>>> IPv6 is not native, but encapsulated in IPv4.  The IPv4 encapsulating
>>>>>>> endpoint could be on Dishy.
>>>>>>>
>>>>>>> Alex
>>>>>>>
>>>>>>> Le 08/12/2023 à 13:24, Steven a écrit :
>>>>>>>> Alexandre,
>>>>>>>>
>>>>>>>>> Are you sure the DHCPv6-PD server is in Starlink network and not on the
>>>>>>>>> MikroTik router?
>>>>>>>> That would be quite the unusual setup, and even so would require that I obtain said /56 from elsewhere (such as via a tunnel) to then delegate back to myself...
>>>>>>>>
>>>>>>>>> It could be that the MikroTik router runs tunnelbroker, obtains a /56
>>>>>>>>> from HE, splits that /56 into multiple /64s and puts it on the DHCPv6-PD
>>>>>>>>> local server config files.
>>>>>>>> I am confident this is not the case since I configured these routers from scratch.
>>>>>>>>
>>>>>>>>> It could also be that the DHCPv6-PD server is run on the Dishy.
>>>>>>>> It is unlikely that it is on the Dishy, as the latency to the DHCPv6 servers IP address, as well as the first IP hop, indicates the usual Ground->Space->Ground latency I'd expect.
>>>>>>>>
>>>>>>>>> It could also be that the DHCPv6-PD server is run on the starlink ground
>>>>>>>>> network: maybe on the teleport, maybe deeper on the starlink network.
>>>>>>>> Yes, this is the most likely place they are running this, likely the PoP you are being routed through.
>>>>>>>>
>>>>>>>>> Do you know the IPv6 address of your DHCPv6-PD Server?
>>>>>>>> The DHCPv6 server address is a Starlink IPv6 address, the same one as my default gateway (`2406:2d40:xxx:xxx::1`). The /56 I am being allocated is also from the same /32 as this DHCPv6 server, with the /32 being 2406:2d40::/32, which you'll note is allocated to Starlink.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Steven
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