Software-Defined Networking (SDN) helps organizations accelerate
application deployment and delivery, dramatically reducing IT costs
through policy-enabled work-flow automation. SDN technology enables
cloud architectures by providing automated, on-demand application
delivery and mobility at scale. SDN enhances the benefits of data center
virtualization, increasing resource flexibility and utilization and
reducing infrastructure costs and overhead.
SDN accomplishes these business objectives by converging the management of network and application services into centralized, extensible orchestration platforms that can automate the provisioning and configuration of the entire infrastructure. Common, centralized IT policies bring together disparate IT groups and work flows. The result is a modern infrastructure that can deliver new applications and services in minutes, rather than the days or weeks required in the past.
SDN delivers speed and agility when deploying new applications and business services. Flexibility, policy, and programmability are the hallmarks of Cisco's SDN solutions, with a platform capable of handling the most demanding networking needs of today and tomorrow.
The OpenFlow protocol can be used in SDN technologies. The SDN architecture is:
Originally, SDN focused solely on separation of the control plane of the network, which makes decisions about how packets should flow through the network from the data plane of the network, which actually moves packets from place to place. When a packet arrives at a switch in the network, rules built into the switch's proprietary firmware tell the switch where to forward the packet. The switch sends every packet going to the same destination along the same path, and treats all the packets the exact same way. In a classic SDN scenario, rules for packet handling are sent to the switch from a controller, an application running on a server somewhere, and switches (also known as data plane devices) query the controller for guidance as needed, and provide it with information about traffic they are handling. Controllers and switches communicate through a controller's south bound interface, usually OpenFlow, although other protocols exist.
Where a traditional network would use a specialized appliance such as a firewall or link-load balancer, an SDN deploys an application that uses the controller to manage data plane behavior. Applications talk to the controller though its north-bound interface. As of the end of 2014, there is no formal standard for the application interface of the controller to match OpenFlow as a general south-bound interface. It is likely that the OpenDaylight controller's northbound application program interface (API) may emerge as a defacto standard over time, given its broad vendor support.
software-defined networking uses an operation mode that is sometimes called adaptive or dynamic, in which a switch issues a route request to a controller for a packet that does not have a specific route. This process is separate from adaptive routing, which issues route requests through routers and algorithms based on the network topology, not through a controller.
With SDN, the administrator can change any network switch's rules when necessary -- prioritizing, de-prioritizing or even blocking specific types of packets with a very granular level of control. This is especially helpful in a cloud computing multi-tenant architecture, because it allows the administrator to manage traffic loads in a flexible and more efficient manner. Essentially, this allows the administrator to use less expensive commodity switches and have more control over network traffic flow than ever before.
SDN accomplishes these business objectives by converging the management of network and application services into centralized, extensible orchestration platforms that can automate the provisioning and configuration of the entire infrastructure. Common, centralized IT policies bring together disparate IT groups and work flows. The result is a modern infrastructure that can deliver new applications and services in minutes, rather than the days or weeks required in the past.
SDN delivers speed and agility when deploying new applications and business services. Flexibility, policy, and programmability are the hallmarks of Cisco's SDN solutions, with a platform capable of handling the most demanding networking needs of today and tomorrow.
Concept
Software-defined networking (SDN) is an architecture purporting to be dynamic, manageable, cost-effective, and adaptable, seeking to be suitable for the high-bandwidth, dynamic nature of today's applications. SDN architectures decouple network control and forwarding functions, enabling network control to become directly programmable and the underlying infrastructure to be abstracted from applications and network services.
The OpenFlow protocol can be used in SDN technologies. The SDN architecture is:
- Directly programmable: Network control is directly programmable because it is decoupled from forwarding functions.
- Agile: Abstracting control from forwarding lets administrators dynamically adjust network-wide traffic flow to meet changing needs.
- Centrally managed: Network intelligence is (logically) centralized in software-based SDN controllers that maintain a global view of the network, which appears to applications and policy engines as a single, logical switch.
- Programmatically configured: SDN lets network managers configure, manage, secure, and optimize network resources very quickly via dynamic, automated SDN programs, which they can write themselves because the programs do not depend on proprietary software.
- Open standards-based and vendor-neutral: When implemented through open standards, SDN simplifies network design and operation because instructions are provided by SDN controllers instead of multiple, vendor-specific devices and protocols.
Originally, SDN focused solely on separation of the control plane of the network, which makes decisions about how packets should flow through the network from the data plane of the network, which actually moves packets from place to place. When a packet arrives at a switch in the network, rules built into the switch's proprietary firmware tell the switch where to forward the packet. The switch sends every packet going to the same destination along the same path, and treats all the packets the exact same way. In a classic SDN scenario, rules for packet handling are sent to the switch from a controller, an application running on a server somewhere, and switches (also known as data plane devices) query the controller for guidance as needed, and provide it with information about traffic they are handling. Controllers and switches communicate through a controller's south bound interface, usually OpenFlow, although other protocols exist.
Where a traditional network would use a specialized appliance such as a firewall or link-load balancer, an SDN deploys an application that uses the controller to manage data plane behavior. Applications talk to the controller though its north-bound interface. As of the end of 2014, there is no formal standard for the application interface of the controller to match OpenFlow as a general south-bound interface. It is likely that the OpenDaylight controller's northbound application program interface (API) may emerge as a defacto standard over time, given its broad vendor support.
software-defined networking uses an operation mode that is sometimes called adaptive or dynamic, in which a switch issues a route request to a controller for a packet that does not have a specific route. This process is separate from adaptive routing, which issues route requests through routers and algorithms based on the network topology, not through a controller.
With SDN, the administrator can change any network switch's rules when necessary -- prioritizing, de-prioritizing or even blocking specific types of packets with a very granular level of control. This is especially helpful in a cloud computing multi-tenant architecture, because it allows the administrator to manage traffic loads in a flexible and more efficient manner. Essentially, this allows the administrator to use less expensive commodity switches and have more control over network traffic flow than ever before.
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