Which action is one of the MANRS core actions that helps ensure legitimate BGP sessions are established?

• A. Authenticating BGP sessions.
• B. Global monitoring.
• C. Filtering and rejecting bogus routes.
• D. Preventing route leaks.

Answer: (A)

Authenticating BGP sessions is about making sure a peering session is with the intended neighbor and that the session data isn’t tampered with or spoofed. By requiring credentials or trusted mechanisms on the TCP connection between peers, a router will only form or sustain a session with a neighbor that proves its identity. This directly prevents attackers from impersonating a legitimate peer or hijacking a session, ensuring that BGP conversations happen only with trusted partners.

Global monitoring, while valuable for detecting anomalies across the routing ecosystem, helps observe what’s happening rather than guarantee who is establishing the session. Filtering and rejecting bogus routes protect the content of the routing updates once a session exists, not the authenticity of the session itself. Preventing route leaks addresses how routes are shared or restricted between neighbors, not whether the peering session is legitimate.