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- 3 perspectives of SDN Landscape
- How many layers in the SDN Layers 1. A plane-oriented view (management, control, data) 2. The SDN layers 3. A system design perspective
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- Infrastructure SDN infrastructure consists of networking equipment (routers, switches and other middlebox hardware). All they do is forward, and all logic to operate them is done with SDN controller.
ex) Switch Light (OpenFlow switch)
- Southbound interfaces
- Network Virtu- alization
- Network Oper- ating Systems
- Northbound Interfaces
- Lan- guage-based vir- tualization
These are interfaces that act as connecting bridges between control and forward- ing elements. Separate control and data plane.
ex) OpenFlow
the transformation of a network that was once hardware-dependent into a network that is software-based
SDNs goal is to ease network management by using a logically centralized con- troller: the network operating system (NOS). NOS provides abstractions, essential services and common APIs to developers
Northbound interfaces are supposed to be a mostly software based, as opposed to the Southbound interfaces.
Use programming languages that support virtualization such as Pyretic
- Network pro- gramming lan- guages
- Network appli- cations:
- OpenFlow Flow Tables
- What's the main purpose of southbound in- terfaces?
- What are three informa- tion sources pro- vided by Open- Flow protocol?
Network programmability can be achieved using low-level or high-level program- ming languages.
Using low-level languages, it is diflcult to write modular code, reuse it and it generally leads to more error-prone development.
High level programming languages in SDNs make development more modular, code more reusable in control plane, and allow faster development.
These are the functionalities that implement the control plane logic and translate to commands in the data plane. Apps such as routing, load balancing, security enforcement,
It is based on a pipeline of flow tables where each entry of a flow table has three parts: a) a matching rule
b) actions to be executed on matching packets
c) counters that keep statistics of matching packets.
When a packet arrives, the lookup process starts in the first table and ends with either a match in one of the tables of the pipeline or with a miss
The Southbound interfaces or APIs are the separating medium between the control plane and data plane functionality.
- Event-based messages that are sent by forwarding devices to the controller when there is a link or port change.
- Flow statistics are generated by forwarding devices and collected by the con- troller.
- What are the two main operations of P4 forwarding model?
- What are the applications of SDN? Provide ex- amples of each application.
ular protocol, the controller defines a packet parser and a set of tables mapping matches and their actions
Target independence - packet processing programs should be programmed in- dependent of the underlying target device, programs written in P4 should be converted into target-dependent programs by a compiler
Configure - programming of the parser, specify header fields to be processed in each stage of packet processing
Populate - allows addition / deletion of the entries in the tables, decides the policies to be applied to matching packets
Traflc engineering - optimize traflc flow to minimize power consumption
Mobility and wireless - provides an abstraction layer, decoupling wireless protocols from the management of the data plane entities
Measurement and monitoring - enables systems to respond to changes in network conditions
Security and dependability - impose security policies on entry points into the network
Data center networking - live network migration, troubleshooting, real-time mon- itoring
- Which BGP limita- Routing using only destination IP prefix tions can be ad- dressed by using SDN?
- What's the pur- pose of SDX?
Networks have little control over end-to-end paths
(Proposed for IXPs) Application-specific peering
- Describe the SDX architecture.
- What are the ap- plications of SDX in the domain of wide area traffic delivery?
Traflc engineering Traflc load balancing Traflc redirection through middleboxes
SDX virtualized the BGP route server architecture used in traditional internet ex- change points. Each autonomous system has the illusion that it has its own virtual SDN switch connecting its border router to every other participant autonomous system
Application specific peering
Inbound traflc engineering
Wide-area server load balancing
Redirection through middle boxes
