Load Balancing for Stateful Forwarding by Mitigating Heavy Hitters: A Case for Multi-Threaded NDN Software Routers

Equal load balancing for dispatching incoming packets to multiple threads is a crucial requirement in the stateful forwarding of multi-threaded software routers to achieve high-speed forwarding and low packet loss simultaneously. However, equal load balancing is not trivial for Named Data Networking (NDN) routers because of their stateful forwarding. In other words, the consistency of flow states should be maintained so that multiple threads do not access the states simultaneously. Sharding, wherein packets of the same flow are dispatched to the same thread while keeping loads of threads equal, has been proposed; however, in this study, we reveal that heavy hitters like popular content packets cause load imbalance, which may eventually cause packet losses. This study proposes a load balancing mechanism for NDN routers by exploiting the fact that states of flows need not be rigorously maintained when content packets are returned from caches at intermediate routers.