In BGP, what characterizes the open sent state?

• A. The router received agreement on the parameters for establishing a session.
• B. An open message was sent with the parameters for the BGP session.
• C. The router found a route to the neighbor and has completed the three-way handshake.
• D. Peering is established and routing begins.

Answer: (B)

OpenSent represents the moment BGP starts negotiating the session parameters. After the TCP connection is up, the speaker sends an OPEN message that carries the session details: BGP version (usually 4), its own AS number, the hold time, the router ID, and any optional capabilities. This is the step where the parameters for the BGP session are proposed. The router then waits for the neighbor’s OPEN and, once validated, moves toward OpenConfirm and finally Established. The other statements describe later stages or different events (receiving the neighbor’s parameter agreement, TCP handshake, or actually establishing the peering and starting to route), which occur after OpenSent.