Abstract

This paper presents ScaleBricks, a new design for building scalable, clustered network appliances that must “pin ” flow state to a specific handling node without being able to choose which node that should be. ScaleBricks applies a new, com-pact lookup structure to route packets directly to the appro-priate handling node, without incurring the cost of multiple hops across the internal interconnect. Its lookup structure is many times smaller than the alternative approach of fully replicating a forwarding table onto all nodes. As a result, ScaleBricks is able to improve throughput and latency while simultaneously increasing the total number of flows that can be handled by such a cluster. This architecture is effective in practice: Used to optimize packet forwarding in an existing commercial LTE-to-Internet gateway, it increases the through-put of a four-node cluster by 23%, reduces latency by up to 10%, saves memory, and stores up to 5.7x more entries in the forwarding table.