Linux doesn't have a big "enable IPv6" switch, so it's not clear what you mean. The only way I can think of getting the behaviour you describe is if you config

Linux doesn't have a big "enable IPv6" switch, so it's not clear what you mean. The only way I can think of getting the behaviour you describe is if you configure the network to hand out v6 addresses and routes to hosts, and then just black hole the packets. What you have then is a broken network.