Some of the providers exist to provide connectivity to only a specific group of Network Service Subscribers. Other providers place no constraints on the subscribers that can subscribe to them, as long as the subscribers pay the fee charged by the providers. There is no centralized control over all the providers in the Internet. The providers do not always coordinate their efforts with each other, and quite often are in competition with each other. Therefore, there is a need to balance the providers' goals and objectives against the public interest of Internet-wide connectivity and subscribers' choices.
Further work is needed to understand how to reach the balance.
Source preferences allow an originator of a packet to exert control over the path to a destination. Destination preferences allow a destination to exert control over the path from a source to the destination. In view of a potentially wide variety of routing requirements, we need to get a better understanding on the relative practical importance of various routing requirements. In practice organizations usually don't formulate their routing requirements in a vacuum. For example, since the primary role of a provider is to provide services to a set of subscribers, the provider usually formulates its routing requirements based on the set of the routing requirements of the subscribers the provider is expected to serve.