Minimizing Latency Due to Flow Table Overflow by Early Eviction of Flow Entries in SDN

Abstract

An Open vSwitch (OVS) stores flow entries in a flow table which is located on an extremely fast and efficient associative memory, Ternary Content Addressable Memory (TCAM). This TCAM is limited in size and therefore in scenarios of huge data traffic these may overflow and incur huge latency and packet loss. Our aim is to address these issues. In this paper we propose an early eviction strategy to evict the flow entries before the flow table overflows, based on analysis of couple of network parameters, namely number of hosts and packet arrival speed. We construct a relation between these parameters and eviction threshold, which is the value that decides the capacity of the flow table at which flow entries are to be evicted, to find the optimal threshold that minimizes the latency and packet loss. We have realized the results on star topology with single switch and multiple hosts, with a flow table limit of 10 entries. The simulation results show drastic decrease in latency and packet loss when flows are evicted early compared to when they are evicted after the table overflows. � 2018 IEEE.