Module 1: History of SDN
- Discuss the timeline of SDN from the 1980s to present
- Gain awareness about the ideas and principles behind SDN
- Recognize architectural themes in computer networking where SDN originated.
The Four Chapters of SDN History
- Evolution of supporting technologies
- Control-data plane separation
- Developing control channels for specific data planes
- Convergence of control channels and data planes
Evolution of Supporting Technologies
- Central network control: Dates back (at least) to AT&T’s network control point (1980s)
- Programmability in networks: Active networks (1990s)
- Network virtualization: Switchlets, XEN, VINI (1990s)
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Early Days: Control and Data Together
- In-band signaling
- Data and control sent over same channel
- Certain frequencies (e.g., 2600 Hz) could reset phone trunk lines, route calls
- Resulting network was brittle, insecure, etc.
Network Control Point
- Telephone network
- Signaling at NCP
- Benefits
- Services on demand
- Rapid introduction of new services
Benefits of the NCP in the AT&T Network
- Elimination of in-band signaling reduces expenditures
- Shorter circuit holding time
- Ability to determine busy/idle status before requesting a circuit
- Rapid introduction of new services
- “In the area of new services that can be supported…possibilities are limited only by imagination.
Apps from Composing Basic Primitives
- Collect N digits
- Send a message to the NCP
- Make a billing record
Envisioned Service: Person Locator
- User registers location with NCP database
- NCP routes call to the current location/number
- NCPs currently used to route 800 calls
Benefits of Central Control
- Network-wide vantage point
- Can directly observe (rather than infer) networkwide behavior
- Independent evolution of infrastructure, data, and services
- Services and resource allocation decisions can be made based on customer data, network load, etc.
Evolution of Supporting Technologies
- Central network control: Dates back (at least) to AT&T’s network control point (1980s)
- Programmability in networks: Active networks (1990s)
- Network virtualization: Switchlets, XEN, VINI (1990s)
- Discuss the timeline of SDN from the 1980s to present
- Gain awareness about the ideas and principles behind SDN
- Recognize architectural themes in computer networking where SDN originated.
- Evolution of supporting technologies
- Control-data plane separation
- Developing control channels for specific data planes
- Convergence of control channels and data planes
- Central network control: Dates back (at least) to AT&T’s network control point (1980s)
- Programmability in networks: Active networks (1990s)
- Network virtualization: Switchlets, XEN, VINI (1990s)
- In-band signaling
- Data and control sent over same channel
- Certain frequencies (e.g., 2600 Hz) could reset phone trunk lines, route calls
- Resulting network was brittle, insecure, etc.
- Telephone network
- Signaling at NCP
- Benefits
- Services on demand
- Rapid introduction of new services
- Elimination of in-band signaling reduces expenditures
- Shorter circuit holding time
- Ability to determine busy/idle status before requesting a circuit
- Rapid introduction of new services
- “In the area of new services that can be supported…possibilities are limited only by imagination.
- Collect N digits
- Send a message to the NCP
- Make a billing record
- User registers location with NCP database
- NCP routes call to the current location/number
- NCPs currently used to route 800 calls
- Network-wide vantage point
- Can directly observe (rather than infer) networkwide behavior
- Independent evolution of infrastructure, data, and services
- Services and resource allocation decisions can be made based on customer data, network load, etc.
- Central network control: Dates back (at least) to AT&T’s network control point (1980s)
- Programmability in networks: Active networks (1990s)
- Network virtualization: Switchlets, XEN, VINI (1990s)
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