MANRS (Mutually Agreed Norms for Routing Security)
acronymnetworkinggovernance & risk
A community agreement on baseline routing hygiene: filter announcements from your customers, prevent traffic with spoofed source addresses from leaving your network, keep your public routing data accurate, and coordinate with other operators.
It is not a standard or a protocol but a published set of commitments with a participant list, which makes it a reputational instrument as much as a technical one. That is the point - most routing incidents are caused by an operator not doing one of four unglamorous things, and no protocol change can force them. When a network is asked why it accepted an impossible announcement, the answer is almost always that nobody had made filtering someone's explicit job.
Also known as: routing security norms, prefix filtering, anti-spoofing