If this is for use during outages, I want to know exactly what network path is used, ideally with as few hops as possible. Starlink can’t guarantee that.
From there the worst that can happen generally is that the packets spiral the wrong way around the continent
I see you haven't met Google's production backbone network(s)... We intentionally didn't connect the Middle East and India (due to a combination of geopolitics and concerns around routing instability), so any traffic between the two would go the long way around the world, incurring a 200+ ms RTT penalty.
(There was a ThousandEyes report back in 2018 that gave us a black eye. See pages 20-22 of https://pc.nanog.org/static/published/meetings/NANOG75/1909/...)
Agreed entirely on your point that if you're buying multiple redundant links, you're responsible for making sure that they're actually relying on different underlying fiber spans.
That's the point. If you want a reliable separate path, you must test it, and you must be prepared to spend time and money on fixing it. The tests include calling up the engineering manager for the separate path and verifying that it has not been "re-groomed" into sharing a path with your primary -- monthly or quarterly, depending on your risk tolerance.
Operations work does not end because the world keeps changing.
they have incentive and capability to get that traffic off the shared fate should it occur (even if that extends up to starlink serving one of their IP transit providers for OOB). that's why i question the wisdom of being overly concerned with starlink's particular paths.
In practice I don’t know how rapidly they’re able to route around damage to the ground network that could be shared, though.
That means Starlink can, in fact, guarantee communications during outages (so long as the Starlink network itself isn't down). You just need to have Starlink service at both the send and receive sides and the communication effectively acts as a direct link.