BGP Route Leak

What is a BGP Route Leak?

The Internet Engineering Task Force (IETF) in RFC 7908 provides a working definition of a BGP Route Leak as "the propagation of routing announcement(s) beyond their intended scope. That is, an announcement from an Autonomous System (AS) of a learned BGP route to another AS is in violation of the intended policies of the receiver, the sender, and/or one of the ASes along the preceding AS path."

RFC 7908 goes on to say "the result of a route leak can be redirection of traffic through an unintended path that may enable eavesdropping or traffic analysis and may or may not result in an overload or black hole. Route leaks can be accidental or malicious but most often arise from accidental misconfigurations."

Comprehensive BGP-layer visibility can help network operators identify the upstream ISPs that most likely propagated the bad routes advertised during a BGP route leak. Route leaks can be identified by utilizing network monitoring tools that are able to conduct synthetic web application testing while visualizing or altering on BGP initiated route changes in real-time.