1. Scenarios, Niches, Architectures
Special Topic: Software Defined Networks
Rudra Dutta
Computer Science, NCSU

2. SDN Picture A new(-ish) paradigm, a general technique:
Create open, standardized, remote access interfaces to settings that did not previously have such interfaces
Can use software (agile) to access these interfaces
Forwarding engine can perform standard forwarding functionality efficiently (perhaps hardware)
Separation of policy and mechanism (into boxes)
For achieving goals and characteristics:
Apply network-level (e.g. routing) policies at fine-grain
Mixing-and-matching forwarding elements, policy elements, other service elements (e.g. monitoring)
Isolate and provide predictable performance for fine-grain customer traffic elements
Do all of the above in agile, non-disruptive manner
Copyright Rudra Dutta, NCSU, Spring 2017

3. Architecture, Common or Not
To realize above visions, may be necessary to create standardized interfaces
So that separate architectural entities can be separate
And be mixed-and-matched
Conversely, absence of architectural interfaces defined / standardized can discourage open interchangeable / interoperable elements
Essentially fragments architecture, creates multiple competing architectural silos
Copyright Rudra Dutta, NCSU, Spring 2017

4. Entity Aggregation
Entities represent roles that different stakeholders (with different interests) can play
Inter-entity interactions requires interface that both (all) agree on  standardized protocol / open interface
If one entity performs multiple (standardized) roles, it must realize every standardized interface at “external” edges, but may ignore standardized interfaces at “internal” edges
Copyright Spring 2017, Rudra Dutta, NCSU

5. Entity Aggregation
Entities represent roles that different stakeholders (with different interests) can play
Inter-entity interactions requires interface that both (all) agree on  standardized protocol / open interface
If one entity performs multiple (standardized) roles, it must realize every standardized interface at “external” edges, but may ignore standardized interfaces at “internal” edges
Copyright Spring 2017, Rudra Dutta, NCSU

6. Open Interfaces vs. Closed Silos
An entity may attempt to maintain external standard interfaces, while speaking proprietary value-added interfaces
Faster/better growth of efficient proprietary interfaces  silo’d solutions
Common architecture allows mixing-and-matching, but requires (larger number of) standardized interfaces
Copyright Spring 2017, Rudra Dutta, NCSU

7. Open Interfaces vs. Closed Silos
An entity may attempt to maintain external standard interfaces, while speaking proprietary value-added interfaces
Faster/better growth of efficient proprietary interfaces  silo’d solutions
Common architecture allows mixing-and-matching, but requires (larger number of) standardized interfaces
Copyright Spring 2017, Rudra Dutta, NCSU

8. Open Interfaces vs. Closed Silos
An entity may attempt to maintain external standard interfaces, while speaking proprietary value-added interfaces
Faster/better growth of efficient proprietary interfaces  silo’d solutions
Common architecture allows mixing-and-matching, but requires (larger number of) standardized interfaces
Copyright Spring 2017, Rudra Dutta, NCSU

9. Architectural Requirement
Open management interfaces
Not just a question of an open standard protocol for NE  NMS communication
Requires a “language” or at least “vocabulary”
SNMP Adopts ASN.1 (subset)
Talking about network concepts of importance
Another component of architecture
Question: What should a common, inclusive architecture for SDN look like?
Components? Entities? Interactions?
No broadly accepted “reference architecture”
Form follows function  examine usecases
Copyright Rudra Dutta, NCSU, Spring 2017

10. Characterizing Usecases / Solutions
Variety of achievable network-level policies
Variety/heterogeneity of
NE capabilities integrated
Efficiency of forwarding
Independent usefulness of coordinated elements
Multiple strength dimensions
Different usecases/solutions require/offer different mix
Architecture should enable all
Copyright Rudra Dutta, NCSU, Spring 2017