Scissors: Dealing with header redundancies in data centers through SDN

Growing concern for reduced power dissipation, cost and latency demands in next generation Data Centers (DC) motivates us to revisit header optimizations. Headers contribute to about 30-40% of DC traffic and is responsible for equal proportion of consumed power. This amounts to significant overhead on per byte transfer of payload. In the past, highly inflexible switches have limited the focus of header optimizations primarily on end-host or edge network routers. Further, strict compliance to protocols by switches/routers along the path have limited the segments of headers that can be optimized. Recent evolution of Software Defined Network (SDN) brings in several opportunities to control over switches. We believe that if SDN's finer handle to the switching devices is exploited, it can help deal with header information. In this paper, we exploit the capabilities of SDN and introduce a new functionality that can effectively replace the redundant and repetitive header information with shorter unique identity. We present Scissor that trims the headers lower in the protocol stack. As a replacement for routing, we introduce the notion of Flow-ID, where all packets belonging to a flow are identified using this unique Flow-ID. We leverage the capabilities of the SDN to dynamically allow switching devices to route the packets based on the Flow-IDs. Our approach of trimming header at the switching devices leaves the hosts unmodified making it highly adoptable for DC environment. We show that our approach can decrease switch fabric power consumption by a factor of 2.5 compared to an existing L2 switch and reduce the latency by about 30% for a significant fraction (around 30-50%) of the network traffic.