Discover the World of Software-Defined Networking
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What is the origin story of SDN?

  • It was created to sell networking equipment
  • It started as an effort to address the ossification of the Internet (correct)
  • It was developed to meet user needs
  • It was invented to implement open source platforms

    • What is the first principle of SDN?

  • To enable network virtualization, automation, and verification
  • To decouple the control and data planes and codify the separation in an open interface (correct)
  • To implement the control plane on-switch
  • To provide high-level abstractions for network control functionality

    • What is the purpose of the Flow Table in SDN?

  • To provide high-level abstractions for network control functionality
  • To enable network virtualization, automation, and verification
  • To implement the control plane on-switch
  • To store the set of flow rules the controller has passed to it (correct)

    • What is the benefit of a programmable data plane in SDN?

    <p>It allows for more efficient and flexible forwarding pipelines</p> Signup and view all the answers

    What is the role of a Network Operating System (NOS) in SDN?

    <p>To provide high-level abstractions for network control functionality</p> Signup and view all the answers

    What is the difference between control and configuration in SDN?

    <p>Control implies making real-time decisions about how to respond to link and switch failures, while configuration is intended for modifying various settings of the control plane and other device parameters</p> Signup and view all the answers

    What is the second design principle of SDN?

    <p>A fully independent and logically centralized control plane</p> Signup and view all the answers

    What is the benefit of a centralized control plane in SDN?

    <p>It allows for globally optimized solutions and provides a single point to expose network APIs, enabling network virtualization, automation, and verification</p> Signup and view all the answers

    What is SDN?

    <p>A networking approach that separates the control plane from the data plane</p> Signup and view all the answers

    What is the origin story for SDN?

    <p>An effort by the Computer Science research community to address the ossification of the Internet</p> Signup and view all the answers

    What is the first principle of SDN?

    <p>To decouple the control and data planes and codify the separation in an open interface</p> Signup and view all the answers

    What is OpenFlow?

    <p>An interface supporting disaggregation that was introduced in 2008 and is a simple-but-powerful way to specify forwarding behavior</p> Signup and view all the answers

    What is the second design principle of SDN?

    <p>A fully independent and logically centralized control plane</p> Signup and view all the answers

    What is a Network Operating System (NOS)?

    <p>A key component of the centralized control plane that provides high-level abstractions for network control functionality</p> Signup and view all the answers

    What is the benefit of a programmable data plane in SDN?

    <p>Allows for more efficient and flexible forwarding pipelines</p> Signup and view all the answers

    What is the purpose of a Flow Table in SDN?

    <p>To store the set of flow rules the controller has passed to the switch</p> Signup and view all the answers

    What is the predominant use case for pure play SDN within cloud datacenters?

    <p>Switching fabrics</p> Signup and view all the answers

    What is SD-WAN and why is it a popular use case for SDN in enterprise networks?

    <p>It allows for centralized control and configuration of VPNs</p> Signup and view all the answers

    What is the CORD initiative and what is its aim?

    <p>It is an initiative to disaggregate legacy devices in access networks</p> Signup and view all the answers

    What is SD-RAN and what is its potential?

    <p>It is a software-defined radio access network</p> Signup and view all the answers

    What is in-band network telemetry (INT) and what does it allow for?

    <p>It is a recent use case for SDN that allows for the collection of network state as packets are being processed</p> Signup and view all the answers

    What is the aim of VNF off-loading?

    <p>To free up compute servers for other tasks</p> Signup and view all the answers

    What is the most likely path-to-adoption for enterprises to adopt SDN?

    <p>Via managed edge services offered by cloud providers</p> Signup and view all the answers

    What is GENEVE and how has it emerged as a more flexible encapsulation technique for virtual networks?

    <p>It is a more flexible encapsulation technique for virtual networks</p> Signup and view all the answers

    What is the predominant use case for pure play SDN within cloud datacenters?

    <p>Switching fabrics</p> Signup and view all the answers

    What is the CORD initiative?

    <p>A software-defined broadband access solution</p> Signup and view all the answers

    What is the purpose of VNF off-loading?

    <p>To free up compute servers for other tasks</p> Signup and view all the answers

    What is SD-RAN?

    <p>A software-defined radio access network</p> Signup and view all the answers

    What is the benefit of SD-WAN in enterprise networks?

    <p>Direct access to cloud services from branch offices</p> Signup and view all the answers

    What is the goal of in-band network telemetry (INT)?

    <p>To provide deeper insights into traffic patterns and network failures</p> Signup and view all the answers

    What is the likely path-to-adoption for enterprises adopting SDN?

    <p>Via managed edge services offered by cloud providers</p> Signup and view all the answers

    What is GENEVE?

    <p>A more flexible encapsulation technique for virtual networks</p> Signup and view all the answers

    What is the predominant use case for pure play SDN within cloud datacenters?

    <p>Switching fabrics</p> Signup and view all the answers

    What is the CORD initiative aiming to do?

    <p>Disaggregate legacy devices in access networks</p> Signup and view all the answers

    What is SD-RAN?

    <p>A software-defined radio access network</p> Signup and view all the answers

    What is the main benefit of SD-WAN in enterprise networks?

    <p>Enabling zero-touch provisioning</p> Signup and view all the answers

    What is in-band network telemetry (INT)?

    <p>A recent use case for SDN</p> Signup and view all the answers

    What is the likely path-to-adoption for enterprises to adopt pure play SDN?

    <p>Via managed edge services offered by cloud providers</p> Signup and view all the answers

    What is GENEVE?

    <p>A more flexible encapsulation technique for virtual networks</p> Signup and view all the answers

    What is VNF off-loading?

    <p>A practice where certain functionality originally provided by legacy hardware is programmed directly into programmable switches</p> Signup and view all the answers

    Study Notes

    Understanding Software-Defined Networking (SDN)

    • SDN is an approach to implementing networks that opens new opportunities to create and deploy innovative solutions to technical challenges.

    • SDN is viewed through a systems lens, which explores the collection of design principles that guide the journey to realizing software-defined networks.

    • SDN emphasizes concepts but also draws on the experience of implementing open source platforms to deliver SDN-based solutions into production networks.

    • The origin story for SDN started as an effort by the Computer Science research community to address the ossification of the Internet, opening it up to more rapid innovation.

    • SDN is an attempt to spur changes in the networking industry by shifting control from vendors that sell networking equipment to network operators that build networks to meet their users’ needs.

    • The end goal of SDN is a horizontal ecosystem with multiple network operating systems enabled on top of bare-metal switches built from merchant silicon switching chips, which in turn enable a rich marketplace of networking applications.

    • The first principle of SDN is to decouple the control and data planes and codify the separation in an open interface.

    • Decoupling the control and data planes implies the need for a well-defined forwarding abstraction, which is a general-purpose way for the control plane to instruct the data plane to forward packets in a particular way.

    • The original interface supporting disaggregation, called OpenFlow, was introduced in 2008 and is a simple-but-powerful way to specify forwarding behavior.

    • Building on the flow rule abstraction, each switch then maintains a Flow Table to store the set of flow rules the controller has passed to it.

    • Control and configuration are related but distinct concepts in SDN. Control implies making real-time decisions about how to respond to link and switch failures, while configuration is intended for modifying various settings of the control plane and other device parameters.

    • The next consideration in SDN is how to implement the control plane. One option is to run the software that implements the control plane on-switch, while the other is a centralized approach.Design Principles and Dimensions of Software-Defined Networking (SDN)

    • SDN is a networking approach that separates the control plane from the data plane, allowing for centralized control and programmability.

    • The control plane can be implemented on or off-switch, but a fully independent and logically centralized control plane is the second design principle of SDN.

    • A Network Operating System (NOS) is a key component of the centralized control plane, providing high-level abstractions for network control functionality.

    • The centralized control plane allows for globally optimized solutions and provides a single point to expose network APIs, enabling network virtualization, automation, and verification.

    • The data plane can be implemented with fixed-function or programmable switches, with the latter allowing for more efficient and flexible forwarding pipelines.

    • Programmable forwarding pipelines, such as the Protocol Independent Switching Architecture (PISA) and P4 programming language, have emerged as a response to the need for high forwarding performance and adaptability to changing protocol stacks.

    • SDN promises to deliver new networking abstractions and accelerate innovation, but the slow-paced standardization processes implied by today's standardized protocols can hinder its realization.

    • The centralized control plane is implemented off-switch, typically in the cloud, and is logically centralized, meaning that the state collected by the controller is maintained in a global data structure.

    • The NOS abstracts the details of the switches and provides a Network Map abstraction to the application developer, making it easier to implement network control functionality.

    • Fine-grained meters, such as the number of bytes/packets sent and received on each port, can be reported to the NOS and used to install new flow rules based on the information collected.

    • A centralized control plane presents a smaller attack surface than a large number of distributed controllers, and techniques developed in the distributed systems world can ensure both high availability and scalability of such clusters.

    • SDN has evolved beyond its original goal as a means to program the control plane and now includes the possibility of a programmable data plane, which allows for more efficient and flexible forwarding pipelines.

    Use Cases of Software-Defined Networking (SDN)

    • Cloud providers like Google, Facebook, and Microsoft have widely deployed SDN, with open sourced individual components to catalyze wider adoption.

    • Large network operators like AT&T, DT, NTT, and Comcast have plans to deploy SDN-based solutions, especially in their access networks, but are proceeding cautiously.

    • Comcast has deployed open source components of SDN throughout their production network.

    • Enterprises have begun to adopt SDN, with pure play SDN deployed in some universities for research and innovation purposes.

    • Adoption of pure play SDN by enterprises is slower, but the most likely path-to-adoption is via managed edge services offered by cloud providers.

    • Many enterprise vendors offer SDN products, with the focus on the benefits of logical control plane centralization rather than open interfaces to the data plane.

    • Network virtualization was the first widely-adopted use case for SDN, enabling lightweight virtual networks with a full set of services for automation and inherent network security.

    • Virtual networks were created by programming virtual switches to forward packets, with appropriate encapsulation, from host to host across the underlay network.

    • GENEVE (Generic Network Virtualization Encapsulation) has emerged as a more flexible encapsulation technique for virtual networks.

    • Switching fabrics are the predominant use case for pure play SDN within cloud datacenters, where cloud providers control the switching fabric interconnecting their servers entirely in software.

    • Traffic engineering applied to the wide-area links between datacenters is another cloud-inspired use case for SDN, with centralizing the decision-making process and differentiating classes of traffic improving network efficiency.

    • These hyperscale experiences with SDN show both the value of being able to customize the network and the power of centralized control to change networking abstractions.SDN Use Cases: From SD-WAN to Network Telemetry

    • SD-WAN is a popular use case for SDN in enterprise networks, as it allows for centralized control and configuration of VPNs, enabling "zero-touch" provisioning and policy management.

    • SD-WAN also allows for direct access to cloud services from branch offices, without backhauling traffic to a central site, while maintaining central control over security policies.

    • Access networks, such as fiber-to-the-home and cellular networks, are a challenge for SDN due to their purpose-built, closed, and proprietary hardware, but offer significant potential benefits.

    • The CORD initiative aims to disaggregate legacy devices in access networks, isolating the packet forwarding engine from the control plane, allowing for commodity hardware and software control.

    • SEBA is an SDN-enabled broadband access solution, with bare-metal OLT devices controlled by a software-defined control plane, with compute servers and access devices interconnected by a switching fabric.

    • VNF off-loading is a practice where certain functionality originally provided by legacy hardware is programmed directly into programmable switches, freeing up compute servers for other tasks.

    • SD-RAN, or software-defined radio access networks, is lagging behind software-defined broadband, but has the potential to lead to a 5G-empowered edge cloud.

    • In-band network telemetry (INT) is a recent use case for SDN, allowing for the collection of network state as packets are being processed, providing deeper insights into traffic patterns and network failures.

    • INT can measure and record queuing delay experienced by individual packets, detect microbursts, and correlate information across packet flows to determine shared buffer capacity.

    • INT can also report the decision-making process that directed packet delivery, allowing for verification that the data plane is executing the intended forwarding behavior.

    • SDN provides the ability to experiment and innovate with new ideas, such as INT, that were previously infeasible with traditional fixed-function ASICs.

    • SDN is not necessarily doing everything it promised, as some control plane to data plane communication channels are proprietary, and SD-WAN and access network solutions are overlay networks running on top of traditional networks.

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    Description

    Test your knowledge of Software-Defined Networking (SDN) with this quiz! Learn about the principles and design dimensions of SDN, including the separation of the control and data planes, the implementation of a centralized control plane, and the use of programmable forwarding pipelines. Discover how SDN can open up new opportunities to create and deploy innovative solutions to technical challenges in the networking industry. Challenge yourself and see how much you know about this exciting approach to networking!

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