Joint Server Selection and SFC Routing for Anycast in NFV-enabled SDNs

Anycast mechanism has been used as a fundamental technology in many fields, with multiple servers providing the same service. Each request does not care which server it is served by. For security and performance reasons, requests must meet the requirements of service function chain (SFC) in network function virtualization (NFV) enabled networks. Though the routing of SFC has been widely studied, most of these works focus on unicast, which does not involve server selection, and cannot be applied directly for anycast. If we simply combine the traditional anycast algorithms and SFC unicast routing algorithms, it will overload the links and servers. Since overloaded links and servers will reduce the quality of services, it is important to balance the load of links and servers. In this work, we focus on designing an SFC routing mechanism for anycast that takes server selection into account and achieves load balancing among servers as well as links with the help of software defined network (SDN). We first propose the problem of joint server selection and SFC routing for anycast in NFV-enabled SDNs (JSR). Then based on the method of random rounding, we design an algorithm called RBLB with approximate ratio guarantee that can solve the JSR problem. The extensive simulation results show that our algorithm can reduce the load of servers and links. For example, algorithm RBLB can reduce the server load by 41.4%–60.1% compared with the comparison algorithm, when the number of requests exceeds 20k.