Oops, I was corrected that HE doesn’t have IPv6 issues with Google, not sure why I had that in my head. Cogent certainly does but something had me thinking there’s another big name that has the same problem.
David
I think what you were remembering is Cogent/Google and Cogent/HE are both IPv6 issues where the parties can't agree on peering vs transit for the v6 relationship.
Why does cogent seem like the commonality between those 2 that you mentioned 
- Aaron
Why do people think the policy as to whether or not they can peer or have to buy transit should be different for one address family vs the other?
Why will some networks peer at an IX but refuse to make changes (like new port IPs or new ASN for the same organization they already peer with)?
Regardless, this is why it pays to multi-home and peer as much as possible. If you directly peer with the networks one of your transit providers is in a pissing match with, the issue is easily ignored.
A careful observer will note multiple fractures/rifts in the ipv6 default-free zone. It’s not as meshed as ipv4, unfortunately.
Kind regards,
Job