It's "popular" in that it's widely deployed, but I think it's fairly unpopular in that people really don't enjoy operating it. When I worked for a high traffic

It's "popular" in that it's widely deployed, but I think it's fairly unpopular in that people really don't enjoy operating it. When I worked for a high traffic website, I was told people would occasionally reach out like "hey can we just ipv6-peer with y'all so our users don't have to talk to you over our cgnat. it's putting a ton of load on the cgnat gateway".