On the Practical Applicability of SDN Research

Transcription

1 On the Practical Applicability of SDN Research Roberto di Lallo Gabriele Lospoto Massimo Rimondini Mirko Gradillo Claudio Pisa IEEE/IFIP Network Operations and Management Symposium Istanbul Turkey 25/29 April 2016

2 4050

3 SDN has been the Future 4050 Number of citations of the original OpenFlow paper Nick McKeown, Tom Anderson, Hari Balakrishnan, Guru Parulkar, Larry Peterson, Jennifer Rexford, Scott Shenker, and Jonathan Turner OpenFlow: enabling innovation in campus networks. SIGCOMM Comput. Commun. Rev. 38, 2 (March 2008),

4 now is the Present

5 Why?

6 Why? Because SDN lets us innovate in a very flexible and customizable way

7 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN

8 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN Closed HW

9 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN Closed SW Closed HW

10 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW

11 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW Standard HW

12 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW Standard Interface (OpenFlow) Standard HW

13 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW Control Software running on general purpose HW Standard Interface (OpenFlow) Standard HW

14 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW Control Software running on general purpose HW Standard Interface (OpenFlow) Standard HW

15 Why? Because SDN lets us innovate in a very flexible and customizable way Before SDN After SDN Closed SW Closed HW Control Software running on HW general purpose Standard Interface (OpenFlow) Standard HW

16 Problem How much do network devices support SDN functionalities through the implementation of the OpenFlow protocol?

17 Problem How much do network devices support SDN functionalities through the implementation of the OpenFlow protocol? Our contribution A critical review of the literature about SDN by: Defining a methodology to verify the support of SDN-related functionalities in a network device Applying our methodology to devices from 7 different vendors

18 (A selection of the) Literature on SDN

19 (A selection of the) Literature on SDN SDN has been attracting the interest of the research community for at least a decade, resulting in a very rich body of contributions

20 (A selection of the) Literature on SDN SDN has been attracting the interest of the research community for at least a decade, resulting in a very rich body of contributions We sampled the literature according to the following criteria: recent contributions dependence on a correct implementation of OpenFlow functions

21 (A selection of the) Literature on SDN SDN has been attracting the interest of the research community for at least a decade, resulting in a very rich body of contributions We sampled the literature according to the following criteria: recent contributions dependence on a correct implementation of OpenFlow functions Grouped in three class:

22 (A selection of the) Literature on SDN SDN has been attracting the interest of the research community for at least a decade, resulting in a very rich body of contributions We sampled the literature according to the following criteria: recent contributions dependence on a correct implementation of OpenFlow functions Grouped in three class: Rules Optimization Deployment Languages

23 (A selection on the) Literature on SDN Rules Optimization SDN has been attracting the interest of the research community for at least a Main decade, goal: resulting reducing in the a very size rich of flow body tables of contributions Works: Selection Optimizing of the One most Big recent Switch ones abstraction that we consider in software-defined most directly impacted by the networks accuracy of OpenFlow implementations Palette: Distributing tables in software-defined networks Grouped Scalable flow-based in three class: networking with DIFANE DevoFlow: Scaling flow management for high- performance networks SwitchReduce: Reducing switch state and controller involvement in openflow networks Deployment Languages Optimizing rules placement in OpenFlow networks: Trading routing for better efficiency

24 (A selection on the) Literature on SDN SDN has been attracting the interest of the research community for at least a Deployment decade, resulting in a very rich body of contributions Main goal: deploying SDN in well-known application scenarios Selection Works: of the most recent ones that we consider most directly impacted by the SDX: accuracy A software OpenFlow defined implementations Internet exchange Rethinking Virtual Private Networks in the software-defined era Grouped Scalable in three programmable class: inbound traffic engineering Wireless mesh software defined networks (wmsdn) Rules Optimizer Languages

25 (A selection on the) Literature on SDN SDN has been attracting the interest of the research community for at least a Languages decade, resulting in a very rich body of contributions Main goal: introducing languages for an abstract specification of packet Selection of the most recent ones that we consider most directly impacted by forwarding policies the accuracy of OpenFlow implementations Works: A compiler and run-time system for network programming languages Grouped in three class: Frenetic: A network programming language Modular SDN programming with Pyretic Rules Optimizer Deployment

26 OpenFlow implementation limitations for some top switch vendors Limitation HP Dell Brocade Arista Networks Extreme Networks Flow table size constraints Restricted match conditions Single flow table No MPLS support Hybrid-port mode unsupported NORMAL port unsupported

27 OpenFlow implementation limitations for some top switch vendors Limitation HP Dell Brocade Arista Networks Extreme Networks Flow table size constraints Restricted match conditions Single flow table No MPLS support Hybrid-port mode unsupported NORMAL port unsupported

28 OpenFlow implementation limitations for some top switch vendors Limitation HP Dell Brocade Arista Networks Extreme Networks Flow table size constraints Restricted match conditions Single flow table No MPLS support Hybrid-port mode unsupported NORMAL port unsupported

29 Device Testing Methodology

30 Device Testing Methodology 1. Goals: 1. Verifying basic and advanced packet handling functions 2. Assessing the switching performance of the datapaths

31 Device Testing Methodology 1. Goals: 1. Verifying basic and advanced packet handling functions 2. Assessing the switching performance of the datapaths 2. Test conditions: 1. Various network topologies 2. Different SDN controllers

32 Device Testing Methodology 1. Goals: 1. Verifying basic and advanced packet handling functions 2. Assessing the switching performance of the datapaths 2. Test conditions: 1. Various network topologies 2. Different SDN controllers 3. Testing tools: 1. Ryu Openflow 1.3 Compliance Test Suite 1. Publicly available 2. Very rich set of test cases 3. Constantly updated 4. Also used by some vendors for compliance tests

33 Device Testing Methodology 1. Goals: 1. Verifying basic and advanced packet handling functions 2. Assessing the switching performance of the datapaths 2. Test conditions: 1. Various network topologies 2. Different SDN controllers 3. Testing tools: 1. Ryu Openflow 1.3 Compliance Test Suite 1. Publicly available 2. Very rich set of test cases 3. Constantly updated 4. Also used by some vendors for compliance tests 2. Custom Tests 1. Manual interaction with the tested datapaths 2. Ad hoc written controllers

34 Ryu Test 1. Four classes of test cases

35 Ryu Test 1. Four classes of test cases 1. Action: verifies packet forwarding and manipulation function 2. Group: verifies support for group actions 3. Match: verifies an extensive assortment of match conditions 4. Meter: verifies support for the meter table

36 Ryu Test 1. Four classes of test cases 1. Action: verifies packet forwarding and manipulation function 2. Group: verifies support for group actions 3. Match: verifies an extensive assortment of match conditions 4. Meter: verifies support for the meter table 2. Every test case is repeated multiple times with test packets that have different sets of headers or transport different protocols

37 Custom tests Functional tests Support for the Normal reserved port Behaviour with multiple configured controllers Existence of hidden flow tables with default entries Targeted versions of selected Ryu test cases Operation of group actions Operation of bitmasks applied on matched header fields Support for pushing/popping single or multiple VLAN tags Support for pushing/popping single or multiple MPLS labels; assessment of label stack size limits Support for metadata in match conditions and actions Performance tests Switching performance as a function of flow table size CPU usage for flow entry matching and packet switching Time required to install entries in the flow table

38 Custom tests Functional tests Support for the Normal reserved port Behaviour with multiple configured controller Existence of hidden flow tables with default entries Targeted versions of selected Ryu test cases Operation of group actions Operation of bitmasks applied on matched header fields Support for pushing/popping single or multiple VLAN tags Support for pushing/popping single or multiple MPLS labels; assessment of label stack size limits Support for metadata2in match conditions and actions Performance tests Switching performance as a function of flow table size CPU usage for flow entry matching and packet switching Time required to install entries in the flow table

39 Devices under test ID 10GbE Ports Switching Fabric Capacity CAM OpenFlow version OVS based S1 8 About 2 Tbps CAM 1.3 No S2 128 About 2 Tbps TCAM 1.3 No S3 64 About 1 Tbps n/a 1.3, 1.4 Yes S4 4 About 500 Gbps TCAM 1.3 No S5 4 About 500 Gbps TCAM 1.3 No S6 72 About 1 Tbps n/a 1.3 No S7 40 About 500 Gbps n/a 1.3 Yes OVS n/a n/a (sw switch) No 1.x Yes

40 Results Count of passed Ryu tests 991

41 Results Count of passed Ryu tests 991

42 Results Count of passed Ryu tests 991

43 Results Count of passed Ryu tests 991

44 Results Per test class

45 Results Per test class

46 Results Per test class

47 Results Per test class

48 Results Per protocol

49 Results Per protocol

50 Results Per protocol

51 Results Per protocol

52 Results Insertion time

53 Results Insertion time

54 Results Insertion time

55 OpenFlow Implementation Limitations (revised)

56 OpenFlow Implementation Limitations (revised) From documentation

57 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests +

58 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests + +

59 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests + + =

60 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests - Dependencies among header fields in flow entries - Ineffective (but admissible) combinations of match conditions + + = Constraints on the structure of flow entries

61 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests - Wilcards consume a lot of space in flow tables - Matching headers of layer 3+ consumes a lot of space in flow tables + + = Flow table capacity restrictions

62 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests - Flow entries failing to be stored - Ineffective table-miss flow entry - Incorrectly updated matched packet counters - Non-deterministic behavior - Malformed OpenFlow packets - Improper flow table IDs - Incorrectly inherited header fields for pushed/popped MPLS tags - Unexpectedly discarded packets - Rules failing to be installed at a high rate + + = Erroneous and inconsistent behaviors

63 OpenFlow Implementation Limitations (revised) From documentation Outcomes of Ryu tests Outcomes of custom tests + + = - (mostly) missing MPLS support Unsupported functions

64 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

65 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

66 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

67 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

68 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

69 Rules Optimization Literature on SDN Deployment Languages Optimizing the One Big Switch abstraction in software-defined networks Palette: Distributing tables in softwaredefined networks Scalable flow-based networking with DIFANE SwitchReduce: Reducing switch state and controller involvement in openflow networks DomainFlow: Practical flow management method using multiple flow tables in commodity switches SDX: A software defined Internet exchange Rethinking Virtual Private Networks in the software-defined era Scalable programmable inbound traffic engineering Wireless mesh software defined networks (wmsdn) Constraints on the structure of flow entries Unsupported functions A compiler and run-time system for network programming languages Frenetic: A network programming language Modular SDN programming with Pyretic Flow table capacity restrictions Erroneous and inconsistent behaviors

70 Conclusions and Future Work

71 Conclusions and Future Work SDN Research in the field of SDN is largely unaware of several restrictions encountered when it comes to deploying a proposed architecture on real devices

72 Conclusions and Future Work SDN Research in the field of SDN is largely unaware of several restrictions encountered when it comes to deploying a proposed architecture on real devices This work estimates the gap between research results and their practical applicability on currently available devices

73 Conclusions and Future Work SDN Research in the field of SDN is largely unaware of several restrictions encountered when it comes to deploying a proposed architecture on real devices This work estimates the gap between research results and their practical applicability on currently available devices Apply our methodology to additional devices Extend our set of custom tests

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