Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

SDN Controller - Programming Challenges

1,753 views

Published on

Published in: Technology, Business
  • Be the first to comment

SDN Controller - Programming Challenges

  1. 1. Sriram NatarajanSDN Controller – ProgrammingChallengesJune 13, 2013
  2. 2. 2Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Software Defined Networking (SDN)PacketForwardingPacketForwardingPacketForwardingPacketForwardingNetwork OSOpenFlow API Network OS vs. Controller (or is it just OF Driver?) Can controller ensure correct programming behavior? Are there any missing pieces?Controller
  3. 3. 3Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.OpenFlow Protocol – Quick OverviewPacketForwardingPacketForwardingPacketForwardingPacketForwardingNetwork OSOpenFlow APIConnection: Logically Centralized? # of Switches/Controllers Setup (TCP/TLS) / Interruption Inband/Out-of-bandMessage Types: Controller-to-switch Asynchronous SymmetricMessage Handling: Delivery Processing OrderingController
  4. 4. 4Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Programming Challenges Consistency Correctness Optimization Performance HeterogeneousPacketForwardingPacketForwardingPacketForwardingPacketForwardingNetwork OSOpenFlow APIControllerMatch Fields Attributes Instructions* priority = 0 Drop10.0.0.1 priority = 100 Output:2
  5. 5. 5Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Consistency Fail secure mode:– Packets to controller -DROPPED Fail standalone mode:– Switch acts as a legacyEthernet switch or router PacketForwardingPacketForwardingPacketForwardingPacketForwardingNetwork OSOpenFlow APIController✕ Retain existing flows– Does not break forwarding– Might be Inconsistent– Query entire flow state Delete all flows– Breaks forwarding– Can restore to consistent state– Re-compute logic or maintain localcopy?ReconnectionInterruption
  6. 6. 6Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Correctness Violations (e.g., conflictingactions) (FortNOX) Misconfigurations(e.g., incorrect flow attributes)ControllerPacketForwardingPacketForwardingPacketForwardingPacketForwardingOpenFlow APISecurity App 2 App 3Match Fields Attributes Instructions* priority DROPconflicting flow updates• If controller acts just like an OF-Driver, will applications talk OpenFlow? What is the rightabstraction?• How to verify correct programming updates?
  7. 7. 7Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Optimization Size– Flow duration (idle/hard timeouts): Reducing timeouts  reduce flowtable size (DevoFlow)– Single Flow Table: Cartesian Explosion Issue (Can be solved by Multi-table) Aggregation– One flow entry covers large groups of flows, can be one entry percategory of flows– Wildcard flow entries– Key: How to optimize flow updates from controller as well as retaincorrect logic?
  8. 8. 8Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Performance Proactive programming when possible– Controller pre-populates flow table in switch– Zero additional flow setup time Leverage hardware features– Number of Connections (OF auxiliary channels)ControllerPacketForwarding(1) Flow Lookup Miss(2)(3) ProcessingTime Flow Setup Time: Flow Lookup Miss +OF Channel RTT +Controller Processing Time +Flow Table Update time(5) Flow TableUpdate Time(4)
  9. 9. 9Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Heterogeneous Switch capabilities– Software switches More features, lowerperformance– Hardware switches Less features, betterperformance Does controller and Appswrite customized code foreach switch? Another Issue:– Different OF VersionsOVSVendor XVendor XSoftswitchNetwork OSOpenFlow 1.0Controller• Need for portable API that can abstract low-level heterogeneityOpenFlow 1.3
  10. 10. 10Copyrights 2013 NTT Innovation Institute, Inc. All rights reserved.Possible Missing PiecesPacketForwardingPacketForwardingPacketForwardingPacketForwardingOpenFlow APIControllerPortable API Run-time systemAbstraction LayerCorrectnessHeterogeneous ConsistencyOptimization
  11. 11. Thanks!

×