ipv6 Tcp Connection If Index
An index object used to disambiguate conceptual rows in the table, since the connection 4-tuple may not be unique. If the connection's remote address (ipv6TcpConnRemAddress) is a link-local address and the connection's local address (ipv6TcpConnLocalAddress) is not a link-local address, this object identifies a local interface on the same link as the connection's remote link-local address. Otherwise, this object identifies the local interface that is associated with the ipv6TcpConnLocalAddress for this TCP connection. If such a local interface cannot be determined, this object should take on the value 0. (A possible example of this would be if the value of ipv6TcpConnLocalAddress is ::0.) The interface identified by a particular non-0 value of this index is the same interface as identified by the same value of ipv6IfIndex. The value of this object must remain constant during the life of the TCP connection.
Back to IPV6-TCP-MIB MIB page.