p.1
Southbound API and OpenFlow
What does the southbound API do in an SDN controller?
It interfaces with SDN devices.
p.1
Southbound API and OpenFlow
What are some alternative protocols to OpenFlow in southbound APIs?
BGP, Cisco CLI, and SNMP.
p.1
Southbound API and OpenFlow
What is the significance of OpenFlow in the context of southbound APIs?
It is the best example of standardization in the southbound interface.
p.1
Southbound API and OpenFlow
What are OF-Config and OVSDB used for?
They are open protocols for the southbound interface, limited to configuration roles.
p.1
Northbound API and Application Interfaces
What is the current deficiency in SDN regarding northbound interfaces?
The lack of a standard for the controller-to-application interface.
p.15
Hypervisor-Based Overlay Networks
What issue does encapsulation in SDN help to solve?
It hides host MAC addresses within the encapsulated frame.
How does RESTCONF relate to NETCONF?
RESTCONF bundles NETCONF requests into easier-to-use REST messages.
What is an active area of research in SDN?
Controlling network behavior via policy.
What traditional methods have been used to set configuration parameters on devices?
CLI (Command Line Interface) and SNMP (Simple Network Management Protocol).
p.14
Hypervisor-Based Overlay Networks
What do virtualized networks and ports abstract from?
Their physical counterparts below.
p.4
Challenges and Issues in SDN
What is a common issue faced by Open SDN controllers?
They suffer from birthing pains common to new technologies.
p.4
Existing SDN Controller Implementations
Which two controllers have assumed dominant roles for commercial applications?
ODL (OpenDaylight) and ONOS.
p.16
Existing SDN Controller Implementations
What are the two main alternatives for software SDN devices?
Open vSwitch (OVS) from Nicira and Indigo from Big Switch.
How do APIs improve agility and automation in SDN?
They allow for quick and automatic responses to changes in the network.
p.5
Flow Management and Prioritization
What is a challenge when managing flows from multiple SDN applications?
Appropriately interleaving the flows from all applications.
p.5
Flow Management and Prioritization
How are flows processed in an SDN device?
In priority order, with the first matching flow acted upon.
p.16
Flow Management and Prioritization
What type of policies are applied in core devices?
Policies that apply to aggregated flows rather than user-centric policies.
p.4
Existing SDN Controller Implementations
What are the advantages of proprietary alternative controllers?
They offer automation and programmability advantages while providing support for network equipment.
Which existing routing protocols are mentioned as being used with SDN?
Border Gateway Protocol (BGP), BGP Link State (BGP-LS), and Path Computation Element Protocol (PCE-P).
p.2
Core Modules of SDN Controller
What is the purpose of Network Device Topology Management?
To maintain information about the interconnection details of network devices and end-user devices.
p.12
Challenges and Issues in SDN
What issue arises when using NETCONF-based APIs?
They may not provide an abstract, network-wide view to the programmer.
p.7
SDN Application Responsibilities
What does centralized control in SDN enable?
Applications to have views of the entire network for optimal policy-based forwarding and routing decisions.
What is one distinct advantage of SDN via APIs?
It works with legacy switches without requiring upgrades to OpenFlow-enabled switches.
p.15
Hypervisor-Based Overlay Networks
What do virtual links represent in SDN?
Tunnels interconnecting virtual tunnel endpoints (VTEPs).
p.14
Hypervisor-Based Overlay Networks
What is the role of hypervisors in virtual networks?
They inject traffic into the virtual network and receive traffic from it.
p.2
Core Modules of SDN Controller
What types of devices does the SDN controller discover?
End-user devices (like laptops and mobile devices) and network devices (like switches and routers).
What protocol does REST use to pass web traffic?
HyperText Transfer Protocol (HTTP).
p.5
Challenges and Issues in SDN
Why might a single standard NBI not be universally needed?
Different ecosystems may grow around each controller, similar to Windows and OSX.
What are the three types of APIs mentioned in SDN?
User application API, Controller API, and Policy API.
p.16
Existing SDN Controller Implementations
What is a characteristic of white box switches?
They are built primarily from merchant silicon switching chips and a commodity CPU and memory by a low-cost Original Device Manufacturer (ODM).
What are the two alternate categories of SDN implementations mentioned?
SDN via APIs and SDN via Hypervisor-Based Overlay Networks.
p.3
Northbound API and Application Interfaces
What methods can be invoked through the Northbound API?
Methods may drop, modify, or forward packets, or add, delete, or modify flows.
p.3
Existing SDN Controller Implementations
What is OpenDaylight?
An open source SDN controller built by a consortium of vendors.
How can the limitation of proprietary APIs be circumvented?
By extending support for multiple vendors’ APIs to mask differences.
p.15
Hypervisor-Based Overlay Networks
How can the overlay strategy be beneficial for new physical networks?
It can be implemented over a new physical network with simpler switches.
p.13
Hypervisor-Based Overlay Networks
What is the concept of Hypervisor-Based Overlay Networks in SDN?
It involves creating virtualized networks above the existing physical network without changing its configuration.
p.6
SDN Application Responsibilities
What are default flow entries in an SDN application?
Static flows that are typically the same for every class of discovered network device.
p.6
SDN Application Responsibilities
What is the significance of state information in SDN applications?
It allows for variable responses based on the current context or user state.
Can applications communicate directly with devices in SDN?
Yes, applications may communicate with devices directly without using a controller.
p.5
Northbound API and Application Interfaces
What is Boulder in the context of SDN?
An intents-based northbound interface (NBI) that supports application communication of network changes.
p.16
Existing SDN Controller Implementations
What is the impact of SDN on physical switching infrastructure?
It can be built from OpenFlow-enabled white box switches at a lower cost than established Network Equipment Manufacturers' switches.
p.2
Core Modules of SDN Controller
What is the primary function of the SDN controller?
To provide core functionality between raw interfaces and applications.
p.5
SDN Application Responsibilities
What is necessary for a simple layer two learning switch to function in SDN?
Additional logic to react to new MAC addresses and update forwarding tables.
p.4
Challenges and Issues in SDN
What is a significant challenge for centralized SDN controllers?
Coordination between applications and the lack of a standard northbound API.
What is a major drawback of using NETCONF or similar APIs in SDN?
It precludes an abstraction layer above.
p.15
Challenges and Issues in SDN
What is a limitation of hypervisor-based overlay networks?
They do not address existing issues within the physical infrastructure.
What must the SDN controller and application programmer synchronize with?
The distributed control plane operating on each switch.
p.2
Core Modules of SDN Controller
What is a flow cache in the context of an SDN controller?
A local maintenance of flow statistics that mirrors the flow tables on different switches.
p.15
Challenges and Issues in SDN
What challenges remain in the physical infrastructure despite using overlays?
Manual configuration, maintenance, traffic prioritization, and efficiency issues.
p.11
Northbound API and Application Interfaces
What is the primary function of SDN via Controller APIs?
It provides SDN functionality in the form of programmability and centralized control, while supporting legacy devices.
p.5
Northbound API and Application Interfaces
What is the emerging standard for the northbound API aimed at?
Developing reusable applications across a wide range of controllers.
p.8
Challenges and Issues in SDN
What are the drawbacks of using CLI and SNMP for device configuration?
They can be cumbersome and difficult to maintain.
p.11
Existing SDN Controller Implementations
What does the distinction between Open SDN controllers and SDN via Controller APIs indicate?
The distinction can become blurred, as both approaches can offer intelligent control of hybrid networks.
p.15
Hypervisor-Based Overlay Networks
How do hypervisor-based overlay networks benefit data centers?
They address MAC address explosion, VLAN limitations, and improve agility and automation.
p.14
Hypervisor-Based Overlay Networks
What is a Tunnel Endpoint or Virtual Tunnel Endpoint (VTEP)?
The edge of the virtual network where packets are encapsulated.
p.7
SDN Application Responsibilities
What is a key functional improvement provided by SDN?
Programmability and centralized control.
p.3
Existing SDN Controller Implementations
What are some examples of open source SDN controllers?
NOX, Beacon, Floodlight, and Trema.
p.14
Hypervisor-Based Overlay Networks
Which companies have their own methods for MAC-in-IP tunneling?
Cisco (VXLAN), Microsoft (NVGRE), and Nicira (STT).
p.2
Core Modules of SDN Controller
How can SDN controllers be tailored to individual network requirements?
By implementing functions via pluggable modules.
p.9
SDN via Controller APIs
How does SDN via Controller APIs promote programmability?
By providing a centralized platform from which to build SDN applications using the controller's APIs.
p.5
SDN Application Responsibilities
What becomes important when multiple SDN applications run on a single controller?
Application prioritization and flow handling.
p.11
Northbound API and Application Interfaces
How do policy-based API solutions benefit SDN applications?
They provide a level of abstraction that shields the SDN application from the complexities of interacting with specific devices.
What does centralized control in SDN via APIs allow for?
Building an SDN solution using provided APIs on distributed network devices.
p.16
Flow Management and Prioritization
How does flow granularity differ between edge and core devices?
Flows are more fine-grained at the edge and more coarse at the core.
p.5
SDN Application Responsibilities
What are the responsibilities of SDN applications?
Managing flow entries, configuring flows, balancing traffic, reacting to topology changes, and redirecting traffic for security tasks.
p.16
SDN Controller Anatomy
What is the role of the SDN controller?
It maintains a view of the entire network, implements policy decisions, controls SDN devices, and provides a northbound API for applications.
p.15
Hypervisor-Based Overlay Networks
Why are VLANs not required in hypervisor-based overlay networks?
Because all traffic is tunneled, allowing for tenant isolation without VLANs.
p.2
Core Modules of SDN Controller
What does Flow Management involve in an SDN controller?
Maintaining a database of flows and coordinating with devices to ensure synchronization.
What is the strategy behind SDN via Device APIs?
To provide a richer set of control points on devices for centralized software manipulation.
p.6
SDN Application Responsibilities
What is the primary function of an SDN application?
To perform specific functions such as load-balancing or firewalling.
p.14
Hypervisor-Based Overlay Networks
What does the virtual network topology consist of?
Virtual switches interconnected by virtual point-to-point links.
p.3
Existing SDN Controller Implementations
What programming languages can interfaces to SDN controllers be offered in?
In the language of the controller or alternatives like REST or Python.
p.6
SDN Application Responsibilities
What happens when there is no matching flow entry for an incoming packet?
The default action is usually to forward the packet to the controller.
p.11
Northbound API and Application Interfaces
What distinguishes imperative systems from declarative systems?
Imperative systems require the user to specify how to perform a task, while declarative systems require the user to specify what needs to be accomplished, leaving the method to the system.
p.15
Hypervisor-Based Overlay Networks
What are VTEPs in the context of SDN?
Virtual Tunnel Endpoints that encapsulate traffic for virtual networks.
p.11
Northbound API and Application Interfaces
What is an example of a declarative API concept in SDN?
The NBI concept of intents, which raises the API level of abstraction for requests.
What is a potential benefit of increased openness in SDN via APIs?
Applications can exploit the exposed interfaces, although they may be proprietary.
p.12
Challenges and Issues in SDN
What is a limitation of API-based SDN methods?
There may be no controller, requiring direct interaction with each switch.
What is the benefit of using the controller API in SDN applications?
Applications can read information about nodes and links without performing device and host discovery.
p.3
Northbound API and Application Interfaces
Why is standardization of the Northbound API important?
It enables a plug-and-play environment for SDN applications across different controllers.
p.14
Hypervisor-Based Overlay Networks
What is MAC-in-IP tunneling?
A method where the entire frame is encapsulated within a unicast IP frame.
p.4
Challenges and Issues in SDN
What is a potential solution for scaling issues in Open SDN environments?
Implementing standards mandated by bodies like the ONF.
What language is used to define data models in NETCONF?
YANG data definition language.
What is a common issue with proprietary APIs in SDN?
They often only work with devices from a specific vendor or a small group of compatible vendors.
How do vendors enhance SDN via Device APIs?
By providing an enhanced level of APIs on their devices beyond traditional CLI and SNMP.
p.6
SDN Application Responsibilities
How does an SDN application respond to events?
By registering as a listener for certain events and invoking callback methods when those events occur.
p.6
SDN Application Responsibilities
What types of events can an SDN application handle?
End-user Device Discovery, Network Device Discovery, and Incoming Packet events.
p.1
Northbound API and Application Interfaces
What opportunities do northbound APIs present?
Opportunities for innovation and collaboration among vendors and the open source community.
p.13
Hypervisor-Based Overlay Networks
What do SDN applications utilize in Hypervisor-Based Overlay Networks?
The resources of the overlay networks.
p.11
Northbound API and Application Interfaces
What is the purpose of policy-level APIs in SDN?
They address network configuration from a declarative perspective, focusing on policies rather than individual device capabilities.
p.16
Existing SDN Controller Implementations
How do legacy switches operate in relation to OpenFlow?
They may operate in both legacy mode and OpenFlow mode.
p.8
Core Modules of SDN Controller
What is the purpose of the Control Forwarding Policy in SDN?
To manage how data is forwarded through the network.
p.3
Northbound API and Application Interfaces
What is the purpose of the Northbound API in SDN?
It allows applications to interact with the SDN controller, affecting network operations.
p.7
Hypervisor-Based Overlay Networks
What is the significance of hypervisor-based overlay networks in SDN?
They allow virtualized overlay networks to be instantiated across the physical network without concern for the underlying infrastructure.
p.5
Northbound API and Application Interfaces
What does the ONF workgroup focus on?
The standardization of the northbound API.
p.3
Existing SDN Controller Implementations
What types of SDN controllers do vendors like NEC, IBM, and HP offer?
Primarily OpenFlow implementations.
What is the benefit of having a single northbound API despite incompatible device interfaces?
It simplifies the application development process.
p.10
Northbound API and Application Interfaces
What do ODL evangelists argue about northbound APIs?
They can be developed to manage hybrid sets of devices.
p.1
Northbound API and Application Interfaces
What types of APIs does the Floodlight controller provide?
A Java API and a RESTful API.
p.14
Hypervisor-Based Overlay Networks
What mechanism allows virtual networks to exist above physical infrastructure?
Tunneling, which uses encapsulation.
p.7
SDN Application Responsibilities
What does programmability in SDN allow for?
The opportunity for applications to automate processes and provide dynamic control.
What is NETCONF used for in the context of SDN?
It is a device management and configuration protocol favored by vendors and customers.
What is one advantage of RESTful APIs regarding firewall configurations?
They require no special firewall configuration as they use a standard TCP port.
p.16
Core Modules of SDN Controller
What common application modules are often bundled with SDN controllers?
Learning switch, router, basic firewall, and simple load balancer.
p.16
Challenges and Issues in SDN
What does Chuck Robbins, Cisco CEO, imply about the future of SDN?
He states that 'Everything we build will be programmable,' recognizing the impact of SDN.
p.10
SDN via Controller Anatomy
What is a key feature of the OpenDaylight (ODL) controller?
It supports multiple southbound protocols.
p.2
Northbound API and Application Interfaces
What is the role of the northbound API in SDN?
To provide access to network devices in a common and consistent manner.
p.2
Northbound API and Application Interfaces
What types of events does the SDN controller communicate to applications?
Events related to individual packets or state changes in the network topology.
p.9
SDN via Controller APIs
What is an example of information that can be gathered using controller-level APIs?
Topology information about devices in the network.
What does the IETF's Interface to the Routing System (I2RS) provide?
An interface between routing protocols and the Routing Information Base (RIB).
p.3
Existing SDN Controller Implementations
Which SDN controller is gaining traction in the carrier market?
Open Network Operating System (ONOS).
p.10
SDN via Controller Anatomy
Which southbound protocols are supported by ODL?
OpenFlow, NETCONF, and BGP-LS/PCE-P.
p.4
Flow Management and Prioritization
What is the significance of flow prioritization in SDN?
It is crucial for managing network traffic effectively.
p.13
Hypervisor-Based Overlay Networks
What remains unchanged in the Hypervisor-Based Overlay Networks approach?
The current physical network and its configurations.
What are the four key drivers inspiring the I2RS protocol?
1. Programmatic, asynchronous interface for atomic operations. 2. Access to structured routing information. 3. Subscription to filterable event notifications. 4. Extensibility with standard data models.
p.4
Challenges and Issues in SDN
What did AT&T plan regarding network functions in the next five years?
To move 75% of their critical future functions to a new software-defined architecture.
p.4
Challenges and Issues in SDN
What is a key aspect that needs to be addressed for successful SDN deployments?
Experience with a wider array of applications and heterogeneous equipment types.
p.9
SDN via Controller APIs
What is one goal of implementing APIs at the controller level?
To provide a level of abstraction between devices and applications.
p.1
Core Modules of SDN Controller
How does the SDN controller abstract device protocols?
It allows applications to communicate with SDN devices without knowing the nuances of those devices.
In the context of SDN via Device APIs, what role does the controller play?
It is optional and adds little or no value to the communication between the application and device.
p.15
Hypervisor-Based Overlay Networks
What is one of the benefits of using overlays in SDN?
The ability to build a virtual network on top of an existing physical one.
p.13
Hypervisor-Based Overlay Networks
What do hypervisor-based virtualized networks obscure?
The details of the physical network from the devices that connect to the overlays.
p.6
SDN Application Responsibilities
What role do external inputs play in SDN applications?
They provide additional data that can influence application behavior and responses.
p.9
SDN via Controller APIs
What is a fundamental distinction between Open SDN and SDN via Controller APIs?
The southbound protocols used; Open SDN uses OpenFlow, while SDN via Controller APIs uses legacy protocols repurposed for SDN functionality.
p.2
SDN Application Responsibilities
What is the significance of network abstraction layers in SDN?
They help in provisioning, configuration management, and automation for networks.
p.6
SDN Application Responsibilities
What is one strength of the SDN architecture?
The ability to control switching decisions through a rich family of applications.
What distinguishes Open SDN from other SDN methods?
Open SDN refers to the original definition of SDN, emphasizing its architecture and control mechanisms.
