Outline • Review – Midterm – SDN and Middleboxes • SDN Wireless Networks – Motivation – Data Plane Abstraction: OpenRadio – Control Plane Architecture • Radio Access Networks: SoftRAN • Core Networks: SoftCell Software Defined Networking (COMS 6998-8) 11/19/13 1
Review of Previous Lecture: Middlebox Basics • A middlebox is any traffic processing device except for routers and switches. • Why do we need them? – Security – Performance – Functionality (e.g. echo cancellation, video transcoding) • Deployments of middlebox functionalities: – Embedded in switches and routers (e.g., packet filtering) – Specialized devices with hardware support of SSL acceleration, DPI, etc. – Virtual vs. Physical Appliances – Local (i.e., in-site) vs. Remote (i.e., in-the-cloud) deployments • They can break end-to-end semantics (e.g., load balancing) Software Defined Networking (COMS 6998-8) 11/19/13 2
Review of Previous Lecture: Middlebox Consolidation VPN Web Mail IDS Proxy Firewall Protocol Parsers Session Management Contribution of reusable modules: 30 – 80 % Software Defined Networking (COMS 6998-8) 11/19/13 3
Review of Previous Lecture: Middlebox State Output Internal to a replica Other Caches ... (ephemeral) processes Application Logic May be shared Threshold Non-critical among replicas counters statistics (coherent) Middlebox VM Flow Table Key Value 5-tuple [Flow State] Partitionable among replicas Input ( Flows ) Software Defined Networking (COMS 6998-8) 11/19/13 4
Outline • Review – Midterm – SDN and Middleboxes • SDN Wireless Networks – Motivation – Data Plane Abstraction: OpenRadio – Control Plane Architecture • Radio Access Networks: SoftRAN • Core Networks: SoftCell 5
Wireless Data Growth • AT&T Global Mobile Data Traffic Growth 2011 to 2016 – Wireless data growth 12 10.8 20,000% in the past Annual Growth 78% 10 Exabytes per Month 5 years 6.9 8 6 4.2 4 2.4 1.3 2 0.6 0 2011 2012 2013 2014 2015 2016 Question: How to Source: CISCO Visual Networking Index (VNI) Global Mobil Data Traffic Forecast 2011 to substantially improve 2016 wireless capacity? 6
OpenRadio: Access Dataplane OpenRadio APs built with merchant DSP (digital signal processing) & ARM (Advanced RISC Machine) silicon Forwarding Dataplane – Single platform capable of LTE, 3G, WiMax, WiFi Control Baseband & CPU – OpenFlow for Layer 3 Layer 2 DSP – Inexpensive ($300-500) Expo poses ses a ma match ch/act ction ion inter erfac face e to pr progr gram m how a f flow RF RF RF is s fo forwarde ded, d, sc schedu duled led & e & enco code ded Source: Katti, Stanford 7
Design goals and Challenges Programmable wireless dataplane using off-the- shelf components – At least 40MHz OFDM-complexity performance • More than 200 GLOPS computation • Strict processing deadlines, eg. 25us ACK in WiFi – Modularity to provide ease of programmability • Only modify affected components, reuse the rest • Hide hardware details and stitching of modules 8 Source: Katti, Stanford 8
Design principle I Judiciously scoping flexibility • Provide just enough flexibility Algorith rithm WiFi LTE 3G 3G DVB-T FIR / IIR √ √ √ √ • Keep blocks coarse Correlation √ √ √ √ Spreading √ • Higher level of abstraction FFT √ √ √ Channel √ √ √ √ • High performance through Estimation hardware acceleration QAM √ √ √ √ Mapping – Viterbi co-processor Interleaving √ √ √ √ – FFT co-processor Convolution √ √ √ √ • Off-the-shelf heterogeneous Coding Turbo Coding √ √ multicore DSPs Randomi- √ √ √ √ – TI, CEVA, Freescale etc. zation CRC √ √ √ 12
A Design principle II Processing-Decision separation C B D • Logic pulled out to decision plane • Blocks and actions are branch-free F G H – Deterministic execution times I J – Efficient pipelining, algorithmic 6M, 54M scheduling – Hardware is abstracted out A B Regular compilation OpenRadio scheduling Instructions Atomic processing blocks 60x C D Heterogeneous functional units Heterogeneous cores E Known cycle counts Predictable cycle counts F Argument data dependency FIFO queue data dependency 13
Prototype I/Q base- RF signal band samples (Analog) (Digital) Baseband-processor unit (BBU) Antenna chain(AX) Radio front end (RFE) Layer 1 & 2 Layer 0 & 1 Layer 0 • COTS TI KeyStone multicore DSP platform (EVM6618, two chips with 4 cores each at 1.2GHz, configurable hardware accelerators for FFT, Viterbi, Turbo) • Prototype can process 40MHz, 108Mbps 802.11g on one chip using 3 of 4 cores 14 Source: Katti, Stanford 14
OpenRadio: Current Status • OpenRadio APs with full WiFi/LTE software on TI C66x DSP silicon • OpenRadio commodity WiFi APs with a firmware upgrade • Network OS Source: Katti, Stanford 15
So Softwar tware e ar archit chitectur ecture BBU RFE AX (Digital) (Analog) OR Wi Wirele eless ss Decisio ision n Plan ane monitor protocol state machine, flowgraph & co composition, block configurations, ntr knowledge plane, RFE control logic OR R Runtime ime System em ol compute resource OR W Wirel eless ss Proce ocessing sing Plane ne scheduling, deterministic signal processing blocks, deterministic execution header parsing, channel resource ensuring protocol data data scheduling, multicore fifo queues, deadlines are met i o sample I/O blocks n u t Bare-metal with drivers 16
Summary Provides programmatic interfaces to monitor and program wireless networks – High performance substrate using merchant silicon 17
Outline • Review – Midterm – SDN and Middleboxes • SDN Wireless Networks – Motivation – Data Plane Abstraction: OpenRadio – Control Plane Architecture • Radio Access Networks: SoftRAN • Core Networks: SoftCell 18
LTE Radio Access Networks • Goal: high capacity wide-area wireless network Base Station (BS) Serving Gateway Packet Data User Equipment (UE) Network Gateway Internet Serving Gateway access core 19
Coping with Increasing Traffic • Increasing demand on wireless resources – Dense deployments – Radio resource management (RRM) decisions made at one base station affect neighboring base stations – RRM needs to be coordinated 20
Radio Resource Management: Interference BS2 BS1 Client1 Client2 • Power used at BS1 affects interference seen at Client 2 • Interference seen at Client 2 affects power required at BS2 21
Radio Resource Management : Mobility BS2 BS1 Client1 Client1 • Coordination required to decide handovers • Load at BS1 reduces and load at BS2 increases 22
LTE-RAN: Current Architecture • Distributed control plane • Control signaling grows with density • Inefficient RRM decision making • Harder to manage and operate the network • Clients need to resynchronize state at every handover • Works fine with sparse deployments, but problems compound in a dense network 23
SoftRAN: Big Base Station Abstraction Big Base Station Radio Element 1 time frequency controller Radio Element 2 Radio Element 3 time time time frequency frequency 24
Radio Resource Allocation Flows 3D Resource Grid time 25
SoftRAN: SDN Approach to RAN Coordination : X2 Interface Control Algo Control Algo OS OS Packet Tx/Rx Control Algo Packet Tx/Rx OS Packet Tx/Rx BS1 BS3 Control Algo Control Algo BS5 OS OS Packet Tx/Rx Packet Tx/Rx BS2 BS4 26
SoftRAN: SDN Approach to RAN Control Algo Operator Inputs Network OS Packet Tx/Rx Packet Tx/Rx Packet Tx/Rx BS1 BS3 BS5 Packet Tx/Rx Packet Tx/Rx BS2 BS4 27
SoftRAN Architecture Summary CONTROLLER RAN Information Base Periodic Updates Controller • Bytes Network API • Rate Operator • Queue Inputs RADIO ELEMENTS Size QoS Interference Flow Constraints Map Records 3D Resource Grid Radio Element Radio Resource Radio Management Element POWER API Algorithm FLOW Frequency 28
SoftRAN Architecture: Updates • Radio element -> controller (updates) – Flow information (downlink and uplink) – Channel states (observed by clients) • Network operator -> controller (inputs) – QoS requirements – Flow preferences 29
SoftRAN Architecture: Controller Design • RAN information base (RIB) – Update and maintain global network view • Interference map • Flow records • Radio resource management – Given global network view: maximize global utility – Determine RRM at each radio element 30
SoftRAN Architecture: Radio Element API • Controller -> radio element – Handovers to be performed – RF configuration per resource block • Power allocation and flow allocation – Relevant information about neighboring radio elements • Transmit Power being used 11/19/13 31 Software Defined Networking (COMS 6998-8)
SoftRAN: Backhaul Latency controller time 32
Refactoring Control Plane • Controller responsibilities: - Decisions influencing global network state • Load balancing • interference management • Radio element responsibilities: - Decisions based on frequently varying local network state • Flow allocation based on channel states 33
Recommend
More recommend
