Circuit‐based logical layer 2 bridging in software‐defined data center networking

Summary With the expansion of the size of data centers, software‐defined networking (SDN) is becoming a trend for simplifying the data center network management with central and flexible flow control. To achieve L2 ions in a multitenant cloud, Open vSwitch (OVS) is commonly used to build overlay tunnels (eg, Virtual eXtensible Local Area Network [VXLAN]) on top of existing underlying networks. However, the poor VXLAN performance of OVS is of huge concern. Instead of solving the performance issues of OVS, in this paper, we proposed a circuit‐based logical layer 2 bridging mechanism (CBL2), which builds label‐switched circuits and performs data‐plane multicasting in a software‐defined leaf‐spine fabric to achieve scalable L2 without overlay tunneling. Our evaluations indicate that direct transmission in OVS improves throughput performance by 58% compared with VXLAN tunneling, and data‐plane multicasting for ARP reduces address resolution latency from 149 to 0.5 ms, compared with control‐plane broadcast forwarding. The evaluation results also show that CBL2 provides 0.6, 0.4, and 11‐ms protection switching time, respectively, in the presence of switch failure, link failure, and port shutdown in practical deployment. We proposed a circuit‐based logical layer 2 bridging mechanism (CBL2), which builds label‐switched circuits and performs data‐plane multicasting in a software‐defined leaf‐spine fabric to achieve scalable L2 without overlay tunneling. Since flow tables in an OpenFlow 1.3‐enabled switch can be linked in sequence to provide pipeline processing, we designed table pipelines, which have a clear division of labor in tables and highly shared forwarding configurations (ie, group entries), to support dynamic expansion of logical L2 networks with low‐network update overhead.