Ultimately, though, the problem remains one of transitive trust. A provider can and should limit the advertisements it will accept from a customer. The mechanics can be arranged manually or can be configured using Routing Policy Specification Language (RPSL) to communicate the policy and drive configuration. In the case of Pakistan Telecom, they originate or transit fewer than 1000 prefixes.
Cutouts is an open source application. Code licensed under the MIT license. Copyright 2018 Siddharth Kannan