This paper introduces Routing Indices (RIs) as an efficient method for content location in peer-to-peer (P2P) systems. RIs allow nodes to forward queries to neighbors that are more likely to have answers, improving performance compared to flooding the network or using random forwarding. The authors present three RI schemes: the compound RI (CRI), the hop-count RI (HRI), and the exponential RI (ERI). They evaluate these schemes through simulations and find that RIs can improve performance by one or two orders of magnitude compared to a flooding-based system and by 50-100% compared to a random forwarding system. The paper also discusses the trade-offs between different RI schemes and the effects of key design variables on system performance. The results show that ERIs and HRI offer significant improvements in query processing while maintaining low update costs. The authors conclude that RIs, particularly ERIs and HRIs, can enhance the search performance of current and future P2P systems.This paper introduces Routing Indices (RIs) as an efficient method for content location in peer-to-peer (P2P) systems. RIs allow nodes to forward queries to neighbors that are more likely to have answers, improving performance compared to flooding the network or using random forwarding. The authors present three RI schemes: the compound RI (CRI), the hop-count RI (HRI), and the exponential RI (ERI). They evaluate these schemes through simulations and find that RIs can improve performance by one or two orders of magnitude compared to a flooding-based system and by 50-100% compared to a random forwarding system. The paper also discusses the trade-offs between different RI schemes and the effects of key design variables on system performance. The results show that ERIs and HRI offer significant improvements in query processing while maintaining low update costs. The authors conclude that RIs, particularly ERIs and HRIs, can enhance the search performance of current and future P2P systems.