Lesson 8 - SDN (part 2) Flashcards
What are the main three perspectives of the SDN landscape?
- A plane oriented view
- The SDN layers
- A system design perspective
List the layers of the SDN-landscape
- Infrastructure
- Southbound interfaces
- Network virtualization
- Network operating systems
- Northbound interfaces
- Language-based virtualizations
- Network programming languages
- Network applications
Summarize the infrastructure layer of the SDN-landscape
SDN infrastructure consists of networking equipment such as routers, switches and other middlebox hardware. Equipment perform simple forwarding tasks, and any logic to operate them is directed from the centralized control system.
Summarize the southbound interfaces layer of the SDN-landscape
These are interfaces that act as connecting bridges between connecting and forwarding elements, and since they sit in between control and data plane, they play a crucial role in separating control and data plane functionality.
Summarize the network virtualization layer of the SDN-landscape
For a complete virtualization of the network, the network infrastructure needs to provide support for arbitrary network topologies and addressing schemes
What is the Network Operating System (NOS) layer of the SDN-landscape?
A network operating system is a specialized operating system for a network device such as a router, switch or firewall.
The value of a NOS is in providing abstractions, essential services and common APIs to developers.
What are the main three parts of each flow table entry utilized in OpenFlow?
a) a matching rule,
b) actions to be executed on matching packets, and
c) counters that keep statistics of matching packets.
What are some possible actions for a packet received by an OpenFlow device?
- Forward the packet to outgoing port
- Encapsulate the packet and forward it to controller
- Drop the packet
- Send the packet to normal processing pipeline
- Send the packet to next flow table
What are three information sources provided by OpenFlow protocol?
- Event-based messages that are sent by forwarding devices to controller when there is a link or port change
- Flow statistics are generated by forwarding devices and collected by controller
- Packet messages are sent by forwarding devices to controller when they do not know what to do with a new incoming flow
What are the core SDN controller functions?
- topology
- statistics
- notifications
- device management
- Shortest path forwarding
- security mechanisms
What are the differences between centralized and distributed architectures of SDN controllers?
centralized - a single entity that manages all forwarding devices in the network. They use multi-threaded designs to explore parallelism of multi-core computer architectures.
distributed - centralized cluster of nodes or physically distributed set of elements (or hybrid)
ONOS (Open Networking Operating System) is a distributed SDN control platform. Describe the purpose of its components.
suggest answer
What is P4?
P4 (Programming Protocol-independent Packet Processors) is a high-level programming language to configure switches which works in conjunction with SDN control protocols. The language was developed to offer programmability on the data plane.
What are the primary goals of P4?
- Reconfigurability
- Protocol independence
- Target Independence
What are the two main operations of P4 forwarding model?
Configure & Populate
Configuration determines the packet processing and the supported protocols in a switch whereas population decides the policies to be applied to the packets.
