Problem Definition and Classification of BGP Route Leaks

Resilient Interdomain Traffic Exchange

“…form of route leak that occurs when a multi-homed customer AS (such as AS3 in Figure 2) learns 446 a prefix update from one transit provider (ISP1) and "leaks" the update to another transit 447 provider (ISP2) in violation of intended routing policies, and the second transit provider does not 448 detect the leak and propagates the leaked update to its customers, lateral peers, and transit ISPs 449 [RFC7908]. Some examples of recent route leak incidents include: 1) the MainOne (a Nigerian 450 ISP) leaks of Google prefixes, which caused an outage of Google services for over an hour in 451…”

“…More generally, as defined in [RFC7908], a route leak is the propagation of routing 455 announcements beyond their intended scope. That is, an AS's announcement of a learned BGP 456 route to another AS is in violation of the intended policies of the receiver, the sender, and/or one 457 of the ASes along the preceding AS path.…”

“…In [RFC7908], several types of route leaks are enumerated and described together with examples 459 of recent incidents. The result of a route leak can include redirection of traffic through an 460 unintended path, which may enable eavesdropping or malicious traffic analysis.…”

Default External BGP (EBGP) Route Propagation Behavior without Policies

“…Permissive default routing policies can result in inadvertent effects such as route leaks [RFC7908], in general resulting in routing of traffic through an unexpected path. While it is possible for an operator to use monitoring to detect unexpected flows, there is no general framework that can be applied.…”

“…Route leaks [RFC7908] are part of the problem, but software defects or operator misconfiguration can also contribute. This document updates [RFC4271] so that routes are neither imported nor exported unless specifically enabled by configuration.…”