My understanding is that
tcp6 is used for connections over IPv6 & tcp is used for connections over IPv4.
::ffff:127.0.0.1 is representing IPv6 address which is mapped to IPv4 address.
But when I use netstat to find open connections on a port like
netstat -anp | grep 31210
I get output as
tcp 0 0 ::ffff:127.0.0.1:64876 ::ffff:127.0.0.1:31210 ESTABLISHED 23755/java
Which means, IPv6 communication is done using tcp.
How is this possible?