Abstract:In software-defined networking (SDN), the overlapping among the matching fields of rules complicates flow table updates. One update often triggers the movement of multiple ternary content addressable memory (TCAM) entries, which increases the update times. In addition, the TCAMs in existing SDN switches are mostly designed with a single port. The TCAM update suspends the packet lookup which affects the packet forwarding in the data plane. Therefore, how to achieve fast update while supporting wire-speed packet lookup is an important research topic to improve network performance. This paper presents a TCAM-based SDN switch with a flow table update system. When multiple network application updates are integrated at the front end and simultaneously sent to the switch, the system can efficiently detect the dependencies between rules and prioritize the rules which need to be quickly updated, so that they can respond quickly. The update algorithm does not need to block the TCAM search operation and can provide interleaved execution of the packet lookups and rule updates. Tests show that these scheduling strategies improve the system performance by balancing the lookup first algorithm and the update first algorithm.
张庭, 陈智康, 刘斌. SDN流表更新的调度与快速响应[J]. 清华大学学报(自然科学版), 2022, 62(5): 917-925.
ZHANG Ting, CHEN Zhikang, LIU Bin. Scheduling and fast response of SDN flow table updates. Journal of Tsinghua University(Science and Technology), 2022, 62(5): 917-925.
[1] CASADO M, FREEDMAN M J, PETTIT J, et al. Rethinking enterprise network control[J]. IEEE/ACM Transactions on Networking, 2009, 17(4):1270-1283. [2] HONG C Y, CAESAR M, GODFREY P. Finishing flows quickly with preemptive scheduling[C]//ACM Special Interest Group on Data Communication (SIGCOMM) Conference Applications, Technologies, Architectures, and Protocols for Computer Communication. Helsinki, Finland, 2012:127-138. [3] BENSON T, ASHOK A, ADITYA A, et al. MicroTE:Fine grained traffic engineering for data centers[C]//Proceedings of the Seventh Conference on Emerging Networking Experiments and Technologies (CoNEXT). Tokyo, Japan, 2011:1-12. [4] JIN X, LI E L, VANBEVER L, REXFORD J. SoftCell:Scalable and flexible cellular core network architecture[C]//Proceedings of the Ninth ACM Conference on Emerging Networking Experiments and Technologies (CoNEXT). Santa Barbara, USA, 2013:163-174. [5] HE P, ZHANG W Y, GUAN H T, et al. Partial order theory for fast TCAM updates[J]. IEEE/ACM Transactions on Networking (TON), 2018, 26(1):217-230. [6] WAN Y, SONG H Y, CHE H, et al. FastUp:Fast TCAM update for SDN Switches in datacenter networks[C]//41st International Conference on Distributed Computing Systems (ICDCS). Washington DC, USA, 2021:887-897. [7] WEN X T, YANG B, CHEN Y, et al. RuleTris:Minimizingrule update latency for TCAM-based SDN switches[C]//36th IEEE International Conference on Distributed Computing Systems (ICDCS). Nara, Japan, 2016:179-188. [8] QIU K, YUAN J, ZHAO J, et al. FastRule:Efficient flow entry updates for TCAM-based OpenFlow switches[J]. IEE Journal on Selected Areas in Communications, 2019, 37(3):484-498. [9] WANG Z J, CHE H, KUMAR M, et al. COPTUA:Consistent policy table update algorithm for TCAM without locking[J]. IEEE Transactions on Computers, 2004, 53(12):1602-1614. [10] MISHRA T, SAHNI S. Duo-dual TCAM architecture for routing tables with incremental update[C]//IEEE Symposium Computers and Communications (ISCC). Riccione, Italy, 2010:503-508. [11] VAROL Y L, ROTEM D. An algorithm to generate all topological sorting arrangements[J]. The Computer Journal, 1981, 24(1):83-84. [12] BRIGHTWELL G, WINKLER P. Counting linear extensions[J]. Order, 1991, 8(3):225-242. [13] Cypress Semiconductor. CYNSE70256 network search engine[EB/OL]. (2003-12)[2021-09-01]. https://www.digchip.com/datasheets/parts/datasheet/115/CYNSE70256-83BHC.php. [14] TAYLOR D E, TURNER J S. ClassBench:A packet classification benchmark[J]. IEEE/ACM Transactions on Networking (TON), 2007, 15(3):499-511.