A new approach to distributed network simulations that eases the burdens on the simulation developer in creating space-parallel simulations is presented. It provides a full-topology knowledge for every federate (simulator instance) to make the best routing decision to destinations simulated at other federates. Later, this technique was used to characterize the benefits of IP Anycast mechanism at large scale. Different IP Anycast scenarios were simulated in a detailed Border Gateway Protocol (BGP) simulator using a realistic large-scale AS topology. Results indicated that Anycast indeed provides higher availability and decreased end-to-end delay. It also showed that Anycast does not provide load balancing, and the BGP overhead associated with a topology change is reduced when Anycast is deployed. In addition, a simulation model of Enhanced Interior Gateway Routing Protocol (EIGRP) was developed and used to present a new approach for host mobility within an AS. The new solution is to allow end systems to retain a fixed IP address as those systems move across subnet boundaries, and to use route advertisement updates (by EIGRP) to inform routers of new or revised routes to reach the mobile hosts as they migrate. The simulation results showed the viability of this approach, and the ability of EIGRP to update routing tables in a timely fashion.