4A0-114: Nokia Border Gateway Protocol Fundamentals for Services

A BGP peer whose TCP session is not established can be in Idle, where BGP is awaiting a start event or has reset after an error, or Active, where it is retrying the TCP three-way handshake. Connect is the state awaiting completion of that handshake, whereas OpenSent is reached only after TCP has been established. Cisco documents that a session which is not up can vary between Idle and Active.