Software-Defined Networking(SDN):A New Approach to Networking


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Software-Defined Networking(SDN):A New Approach to Networking

  1. 1. SOFTWARE-DEFINED NETWORKING(SDN) A New Approach to Networking Anju Ann Joseph Semester: VII Batch: C B-Tech Seminar Sept 2013
  2. 2. 2 Seminar Overview Introduction Why we need new approach? Why not traditional networks? SDN Architecture OpenFlow Approach Virtual Network Overlay Approach Challenges & Future Expectation Conclusion
  3. 3. 3 Introduction Software Defined Networking (SDN) is an evolutionary approach to network design and functionality based on the ability to programmatically modify the behavior of network devices. SDN uses user-customizable and configurable software that’s independent of hardware to expand data flow control. It will make networks more flexible, dynamic, and cost- efficient, while greatly simplifying operational complexity.
  4. 4. 4 The Need for a New Network Architecture Changing Traffic Pattern The Rise of Cloud Services Consumerization of IT “Big data” means more bandwidth Percentageofnetworktraffic
  5. 5.  Control plane: Routing algorithms 5  Management plane: Configure basic activities  Data Forwarding plane: Packet streaming Traditional Computer Networks Data flow is controlled by switches and routers and contains the following basic elements:
  6. 6. Traditional Networks worked well… 6 Hardware based networks have historically shown that they were stable and reliable. Operational capacities were quickly regained after a power loss, without significant external interventions. Operated consistently in varying environments.
  7. 7. 7 1 2 Limitations of Current Networking Technologies Complexity that leads to Static Nature Inconsistent Policies Inability to Scale Vendor Dependence 3 4
  8. 8. Introducing Software-Defined Networking 8 Software Defined Networking (SDN) is an emerging network architecture where network control plane is decoupled from forwarding plane and is directly programmable. Lead by Open Networking Foundation(ONF) SDN-enabled control plane allows the underlying infrastructure to be abstracted Network appears to the applications as a single, logical switch entity
  9. 9. SDN Architecture OpenFlow Switches 9 SDN Control Software Business Appl Business Appl Business Appl Northbound API Southbound API(eg. OpenFlow) INFRASTRUCTURE LAYER CONTROL LAYER APPLICATION LAYER
  10. 10. 10 API Specifies how software components should interact each other. API’s makes it possible to implement basic network functions like path computation, loop avoidance, routing, security and many other tasks. Southbound API Northbound API Allows controller to define the behaviour of switches at the bottom of the architecture Provides a network abstraction interface to the applications and management systems at the top of the architecture
  11. 11. SDN Controller 11 The controller is the core of an SDN network. By running the control plane as software, the controller facilitates automated network management and makes it easier to integrate and administer applications. SDN controllers uses protocols such as OpenFlow to configure network devices It manages flow control to enable intelligent networking.
  12. 12. 12 OpenFlow is a protocol that is used to define the communication interface between the control and forwarding layers. It provides direct access to and manipulation of the forwarding plane of network devices. Uses the concept of flows to identify network traffic. Approach
  13. 13. 13 OpenFlow-enabled Switch Controller Secure Channel Group Table Flow Table Flow Table OpenFlow protocol OpenFlow switch Components: Flow table & Group table Perform packet lookups and forwarding OpenFlow channel Interface that connects a switch to a controller Two types OpenFlow-hybrid OpenFlow-only Pipeline Pipeline process: Maintains sending of packets between flow tables by matching flow entries.
  14. 14. 14 OpenFlow Ports Logically connects each OpenFlow switch Types of ports: standard logical reserved OpenFlow Packet header Version Type Length of Msg Transaction id 0 7 15 31 63 Flow Table
  15. 15. 15 Inside OpenFlow Packet arrives at switch Header fields compared to flow table entries Forwarded to specified port DroppedOREncapsulates packets and sends to controller Controller decides Drops Make new entry in flow table OR Match FoundMatch Not Found
  16. 16. 16 Message Types Controller-to-switch messages • Modify-state • Read-state • Packet-out/in • Barrier • Role-Request Asynchronous messages • Packet-in • Flow-removed • Port-status Symmetric messages • Hello message • Echo request/reply
  17. 17. Benefits of OpenFlow Approach 17 Centralized Control Reduced Complexity through Automation Higher rate of Innovation Increased Network Reliability and Security
  18. 18. Use Case: Network Slicing among large Data Centers 18 Large Data centers have to accommodate many access requests, each seeking a unique policy and security requirements. SDN helps to overcome this by creating logical isolated networks and allow them to be partitioned using slicing technique. Involves abstraction of control plane management, out of each network device into a centralized controller via OpenFlow protocol, helps isolated networks to grow within themselves and also communicate with other networks.
  19. 19. 19 Few vendors who have produced OpenFlow enabled network switches Few OpenFlow based SDN Controllers Programmed in C++/Python on Linux framework Java based controller Focuses on achieving better performance using multithreading MX series IBM Rack Switch
  20. 20. 20 Virtual Network Overlays(VNO) Approach It creates a virtual network infrastructure for the underlying physical network. Using VNO concept, the physical network is partitioned into multiple logical networks that can be individually programmed and managed.
  21. 21. 21 VNOs are based on a ‘map-and-encap’ approach: 1. Mapping performed to find the destination address of the packet 2. Overlay device encapsulates the packet within an overlay header 3. Encapsulated packet is forwarded to destination where it is de-encapsulated Scheme followed by VNO- Tunneling Scheme Ex: VXLAN(Virtual Extensible LAN)
  22. 22. 22 VXLAN(Virtual Extensible LAN) It is a tunneling scheme to overlay Layer2 networks on Layer3. Virtual LANs (VLAN) have similar functioning, but its specifications only allow for up to 4,096 network IDs to be assigned at any given time. Extends the VLAN address space by adding a 24-bit segment ID (VNI)and increasing the number of available IDs to 16 million. VNI can differentiate individual logical networks so millions of isolated Layer 2 networks can co-exist on a common Layer 3 infrastructure. With VLANs, only virtual machines (VMs) within the same logical network can communicate with each other. VXLAN can potentially allow network engineers to migrate VMs across long distances.
  23. 23. Use Case: Multi-tenancy in Cloud Computing Environment 23 In a cloud environment, abstraction of the management layer becomes important to enable more interaction of applications with the networking elements. The virtual network overlay abstracts the underlying physical network, which allows the overlay to move to other physical networks. Virtual Network Overlay stack for Cloud OpenStack OpenStack Plug-in Rest API Virtual Network Switch Hypervisor Tenant 1 Tenant 2 Tenant 3 VXLAN
  24. 24. Challenge 24 To support co-existence with existing devices the existing technologies must have additional enhancement. For ex, the existing standard path computation elements in routers are not sufficient, they need to be enhanced. Future Expectation To find a unique SDN approach.
  25. 25. Some Frequently Raised Questions.. 25 Why is SDN taking so long to adopt? • Enterprises confused about how SDN will specifically save them on network costs • No compelling use-cases Is SDN and network virtualization same? • similar goals • overlapping sets of technologies
  26. 26. Conclusion 26 SDN promises to transform today’s static networks into flexible ,scalable, programmable platforms with the intelligence to allocate resources dynamically. With its many advantages and astonishing industry momentum, SDN is on the way to become- the new approach for networking.
  27. 27. References 27 [1]:Kapil Bakshi,“Considerations for Software Defined Networking(SDN):Approaches and Use Cases,” IEEE Aerospace Conference, March 2013. [2]:“Software-Defined Networking: The New Norm for Networks,” Open Networking Foundation(ONF) White Paper, April 2012. [3]:“Software Defined Networking: A new paradigm for virtual, dynamic, flexible networking,” IBM Systems and Technology Thought Leadership White Paper, October 2012. [4]: Hyojoon Kim and Nick Feamster, “Improving network management using SDN,” IEEE Communications Magazine, February 2013, pp.114-119.
  28. 28. 28 Got any Questions?
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