BloomTime: space-efficient stateful tracking of time-dependent network performance metrics

Abstract

Network monitoring is essential to tasks ranging from planning to troubleshooting. Unfortunately, comprehensive real-time monitoring of complex networks with large traffic volume is challenging. In particular, tracking of time-dependent metrics, such as round-trip latency or transmission rate requires maintaining state and this is hard to scale. We propose BloomTime: a network monitoring primitive in hardware that employs standard bloom filters to approximately track the times between packets. We have prototyped BloomTime on the NetFPGA platform. As a use case, we use BloomTime to monitor the mean and variance of packet inter-arrival times. We have compared BloomTime against end-host measurements and a centralized solution using classic stateful monitoring. We show that BloomTime can monitor 70 times more flows than the traditional stateful approach with approximation errors below 20%. BloomTime was validated in a realistic test environment using real traces. We show that BloomTime can monitor simultaneously 2000 flows on the NetFPGA 1G board (first generation) with 4 MB of SRAM.