Studies towards heterogeneous Mobile Adhoc Network (MANET) as well as inter-domain routing is still in much infancy stage. After reviewing the existing literaturs, it was found that problems associated with scalability, interoperability, and security is not defined up to the mark as it should be part of pervasive computing in future networks. Moreover, it was found that existing studies do not consider the complexities associated with heterogeneous MANET to a large extent leading to narrowed research scope. Hence, this paper introduces a novel scheme called as Secure, Scalable and Interoperable (SSI )routing, where a joint algorithm is designed, developed, and implemented. The outcome exhibits the correctness of this scheme by simulation assisted by analysis for inter-domain routing