Mobius: Packet Re-processing Hardware Architecture for Rich Policy Handling on a Network Processor

Abstract

Network devices generally handle traffic with predefined policies that describe the operation of packets. Since these policies explain network operation, the number of policies in network devices naturally increases as the scale of a network. Unfortunately, processing a large number of policies may lead to performance loss; Although many policies can be stored in memory, a network processor in a network device can only handle a limited number of policies at once so that the policies should be divided and processed into several groups. Thus, the processing time for one packet will be delayed, and it can fill up an input buffer of the device and drop packets. However, improving a processor that supports large capacity is not an efficient way because it also increases the cost of the processor. To address these challenges, we propose a hardware architecture for network processors called Mobius. It allows a processor to re-process packets n more times with different policies by utilizing the idle resources of the processor caused by the propagation time of packets on a wire. Consequently, Mobius extends the capacity of the processor at a low-cost so that more policies can be processed for packets without performance loss. We implement the prototype of Mobius using NetFPGA-SUME and our evaluation demonstrates that Mobius achieves a line-rate throughput with a tiny latency overhead. A comparison with other network processor models shows that Mobius exhibits a similar performance but is more economical.