CS6250 Exam 2 ACTUAL QUESTIONS
AND CORRECT ANSWERS
L7: What spurred the development of Software Defined Networking (SDN)? - CORRECT
ANSWER > SDN arose to make CN more programmable
> Networks are complex/difficult to manage due to the diversity of equipment on the network and
proprietary technologies for the equipment
> These made them highly complex, slow to innovate, and drove up the costs of running a network.
SDN divides the network into two planes (separation of tasks):
1. control plane
2. data plane.
L7: What are the three phases in the history of SDN? - CORRECT ANSWER 1. Active
networks
2. Control and data plane separation
3. OpenFlow API and network operating systems
L7: Summarize each phase in the history of SDN. - CORRECT ANSWER 1. Active networks
2. Control and data plane separation
3. OpenFlow API and network operating systems
Active networks
> Researchers wanted to test new ideas to improve network services. This required standardization of
new protocols by the IETF which was a slow/frustrating process.
> More active networks which wanted to open up network control.
> Community belief: simplicity of the network core was vital to internet success.
The pushes that encouraged active networking:
> Reduction in computation cost
> PL Advancement (like java)
> Advances in rapid code compilation and formal methods.
,Active networking envisioned unified control that could replace individually managing these boxes.
Active networks made three major contributions related to SDN:
> Programmable functions in the network to lower the barrier of innovation
> Introduced the idea of using programmable networks to overcome the slow speed of innovation in
networking.
Active networking produced a framework that described a platform that would support
experimentation with different programming models. This led to network visualization.
Active networking was more involved in redesigning the architecture of networks, so not as much
emphasis was given to performance and security. Since there were no specific short-term problems
that active networks solved, it was harder to see widespread deployment.
The next efforts had a more focused scope and distinguished between control and data planes. This
difference made it easier to focus on innovation in a specific plane and inflict widespread change.
Control and data plane separation
> Network operators were looking for better network-management functions such as control over
paths to deliver traffic.
> Identified that the challenge in network management depended on the way existing routers and
switches tightly int
Expanded History - CORRECT ANSWER Active networks
Intro
Slow and frustrating process to standardize protocols fostered the push for active networks trying to
open up network control
Active networks with their network API went against the concept of keeping the core simple
2 types of programming models in active networking:
Capsule model - carried in-band in data packets
Programmable router/switch model - established by out-of-band mechanisms
Technology push - The pushes that encouraged active networking were:
Reduction in computation cost (more processing into the network).
, Advancement in programming languages. (Java: platform portability, code execution safety, and VM
(virtual machine) technology to protect the active node in case of misbehaving programs).
Advances in rapid code compilation and formal methods.
Funding from agencies such as DARPA (U.S. Defense Advanced Research Projects Agency) for a
collection promoted interoperability among projects. There were no short-term use cases.
Use pull - The use pulls for active networking were:
Network service provider frustration concerning the long timeline to develop and deploy new network
services.
Third party interests to add value by implementing control at a more individualistic nature. This meant
dynamically meeting the needs of specific applications or network conditions.
Researchers' interest in having a network that would support large-scale experimentation.
Unified control over middleboxes. Active networking envisioned unified control that could replace
individually managing these boxes.
Active networks contributions related to SDN:
Programmable functions in the network to lower the barrier to innovation.
While many early visions for SDN concentrated on increasing programmability of the control-plane,
active networks focused on the programmability of the data-plane.
The concept of isolating expe
L7: What is the function of the control and data planes? - CORRECT ANSWER Control plane -
controls forwarding behavior of routers, such as routing protocols and network middlebox
configurations.
Data plane - performs actual forwarding as dictated by the control plane. IP forwarding and layer 2
switching are functions of the data plane.
L7: Why separate the control from the data plane? - CORRECT ANSWER The reasons we
separate the two are:
Independent evolution and development
- Routers only focus on forwarding.
- Improvement in routing algorithms can take place without affecting any of the existing routers.
- By limiting the interplay between these two functions, we can develop them more easily.
Control from high-level software program
AND CORRECT ANSWERS
L7: What spurred the development of Software Defined Networking (SDN)? - CORRECT
ANSWER > SDN arose to make CN more programmable
> Networks are complex/difficult to manage due to the diversity of equipment on the network and
proprietary technologies for the equipment
> These made them highly complex, slow to innovate, and drove up the costs of running a network.
SDN divides the network into two planes (separation of tasks):
1. control plane
2. data plane.
L7: What are the three phases in the history of SDN? - CORRECT ANSWER 1. Active
networks
2. Control and data plane separation
3. OpenFlow API and network operating systems
L7: Summarize each phase in the history of SDN. - CORRECT ANSWER 1. Active networks
2. Control and data plane separation
3. OpenFlow API and network operating systems
Active networks
> Researchers wanted to test new ideas to improve network services. This required standardization of
new protocols by the IETF which was a slow/frustrating process.
> More active networks which wanted to open up network control.
> Community belief: simplicity of the network core was vital to internet success.
The pushes that encouraged active networking:
> Reduction in computation cost
> PL Advancement (like java)
> Advances in rapid code compilation and formal methods.
,Active networking envisioned unified control that could replace individually managing these boxes.
Active networks made three major contributions related to SDN:
> Programmable functions in the network to lower the barrier of innovation
> Introduced the idea of using programmable networks to overcome the slow speed of innovation in
networking.
Active networking produced a framework that described a platform that would support
experimentation with different programming models. This led to network visualization.
Active networking was more involved in redesigning the architecture of networks, so not as much
emphasis was given to performance and security. Since there were no specific short-term problems
that active networks solved, it was harder to see widespread deployment.
The next efforts had a more focused scope and distinguished between control and data planes. This
difference made it easier to focus on innovation in a specific plane and inflict widespread change.
Control and data plane separation
> Network operators were looking for better network-management functions such as control over
paths to deliver traffic.
> Identified that the challenge in network management depended on the way existing routers and
switches tightly int
Expanded History - CORRECT ANSWER Active networks
Intro
Slow and frustrating process to standardize protocols fostered the push for active networks trying to
open up network control
Active networks with their network API went against the concept of keeping the core simple
2 types of programming models in active networking:
Capsule model - carried in-band in data packets
Programmable router/switch model - established by out-of-band mechanisms
Technology push - The pushes that encouraged active networking were:
Reduction in computation cost (more processing into the network).
, Advancement in programming languages. (Java: platform portability, code execution safety, and VM
(virtual machine) technology to protect the active node in case of misbehaving programs).
Advances in rapid code compilation and formal methods.
Funding from agencies such as DARPA (U.S. Defense Advanced Research Projects Agency) for a
collection promoted interoperability among projects. There were no short-term use cases.
Use pull - The use pulls for active networking were:
Network service provider frustration concerning the long timeline to develop and deploy new network
services.
Third party interests to add value by implementing control at a more individualistic nature. This meant
dynamically meeting the needs of specific applications or network conditions.
Researchers' interest in having a network that would support large-scale experimentation.
Unified control over middleboxes. Active networking envisioned unified control that could replace
individually managing these boxes.
Active networks contributions related to SDN:
Programmable functions in the network to lower the barrier to innovation.
While many early visions for SDN concentrated on increasing programmability of the control-plane,
active networks focused on the programmability of the data-plane.
The concept of isolating expe
L7: What is the function of the control and data planes? - CORRECT ANSWER Control plane -
controls forwarding behavior of routers, such as routing protocols and network middlebox
configurations.
Data plane - performs actual forwarding as dictated by the control plane. IP forwarding and layer 2
switching are functions of the data plane.
L7: Why separate the control from the data plane? - CORRECT ANSWER The reasons we
separate the two are:
Independent evolution and development
- Routers only focus on forwarding.
- Improvement in routing algorithms can take place without affecting any of the existing routers.
- By limiting the interplay between these two functions, we can develop them more easily.
Control from high-level software program
