An Architectural Evaluation of SDN Controllers Syed Abdullah Shah, Jannet Faiz, Maham Farooq, Aamir Shafi, Syed Akbar Mehdi National University of Sciences and Technology (NUST), Pakistan 1

Introduction  Several free and commercial SDN controllers are available in the market today: –Free and open source: Floodlight, Beacon, Maestro, NOX, POX etc. –Commercial: Big Switch, NEC, Cisco etc.  Contributions of this paper: –Study software architectures of existing SDN controllers with the aim to identify best practices –Conduct vendor-independent performance study through several micro-benchmarks 2

SDN Controllers  Free and open source SDN controllers used in this study: –NOX –Beacon –Maestro –Floodlight 3

Key Design Features in Controllers  Multicore Support: –The controller uses parallelism to exploit all available cores/processors in the system  Switch Partitioning: –Distribution mechanism of connecting OF switches to controller threads  Packet Batching: –Input: Amount of data read from the network (OF switch) –Output: Amount of data written to the network (OF switch)  Task Batching: –Distribution mechanism of incoming packets to controller threads  Our study reveals two design options for SDN controllers … 4

Design Option # 1 (Push Design) 5  Used by: o NOX o Beacon o Floodlight  Used by: o NOX o Beacon o Floodlight

Design Option # 2 (Pull Design) 6  Used by: o Maestro  Used by: o Maestro

Design Features in SDN Controllers Design Option Multicore Support Switch Partitioning Static I/O Batching Task Batching NOX Opt # 1 (push design) YesStatic (round robin) Static (fixed # of bytes) No Floodlight Opt # 1 (push design) Yes (over- subscription) Static No Beacon Opt # 1 (push design) Yes (over- subscription) StaticStatic (also supports immediate mode) No Maestro Opt # 2 (pull design) YesAdaptive (shared queue) Workload adaptive Yes 7

Performance Evaluation Testbed  Throughput performance: –How many OF requests a controller can handle per seconds? –Metric for studying performance under heavy load –Thread scalability –Switch scalability  Latency performance –How fast can a controller process a single OF request? –Metric for studying performance of single OF request 8 Afrit Cluster OS GNU/Linux # of Nodes 32 Brand HP DL 160 SE Cores per Node 16 # of Cores 512 Memory 768 GB # of GPUs 128 (Nvidia Tesla S1070) Interconnect 10 GigE

cbench – a tool to simulate OF switches 9 Learning Switch Application packet-in packet-out or flow-mod

Throughput Performance – Thread Scalability 10

Throughput Performance – Switches Scalability 11

Latency Performance 12

Key Findings  Controllers designed for high throughput (i.e. large volumes of control traffic and heavy load) perform best with static switch partitioning and packet batching  Controllers designed for delay-sensitive control plane applications should use workload adaptive packet batching and task batching to reduce per-packet latencies: –Immediate mode (sending outgoing packets individually) helps with the latency performance 13

Proposed SDN Controller  To verify our key findings, we implemented these best- practices in a custom SDN controller called JAM  JAM has the following features: –Multi-threaded and scalable –Performance focused –Embedded (Developed for Cavium intelligent NICs) –OpenFlow v1.0 Compliant Controller –Developed in system independent C 14

App : Learning Switch 32 switches, MACs= 100k Flows (million/sec) Number of threads Throughput Mode – Thread Scalability 15

JAM won Cavium’s 2012 Global Multicore Challenge … 16

Summary  This paper conducted a performance study of existing SDN controller on the basis of: –Multicore Support –Switch Partitioning –Packet Batching –Task Batching  Findings: –Controllers designed for high throughput perform best with static switch partitioning and packet batching –Controllers sensitive to latency should use workload adaptive packet batching and task batching  Thanks for your time and patience! 17