Gotta tell you switches only once: Toward bandwidth-efficient flow setup for SDN

摘要

Software-Defined Networking (SDN) has greatly enriched the flexibility of network management. It introduces a central controller to take over most network functions that otherwise reside in distributed forwarding devices. Such a centralized design, however, tends to make control channel a bottleneck due to bandwidth fatigue. Existing work saves control channel bandwidth at the expense of losing visibility of most or mice flows. This paper proposes FastLane, a framework for bandwidth-efficient SDN flow setup without sacrificing global flow visibility. FastLane advocates that the controller inform only a flow's ingress switch of the flow's forwarding path while switches themselves cooperate to complete flow setup. This way, FastLane keeps minimum traffic for flow setup in control channel and leaves the rest to data plane. The analytical results validate FastLane's higher bandwidth efficiency over traditional SDN, especially for relatively long forwarding paths. For a 3-switch path, FastLane can already save more than a half of bandwidth. The saved bandwidth can embrace more flow setups and thus reduces flow latency.