A reference to additional local MIB information.
This should be the highest available related MIB,
corresponding to charSessProtocol, such as Telnet.
For example, the value for a TCP connection (in the
absence of a Telnet MIB) is the object identifier of
tcpConnState. If an agent is not configured to have
such values, the agent returns the object
identifier:
nullConnectionId OBJECT IDENTIFIER ::= { 0 0 }