Computer Networks -CS6250 Exam 2 Questions and
Answers
What are 2 reasons computer networks are complex and difficult to manage that led to the
development of SDN? - ✔✔1. Diversity of network equipment
2. Proprietary technology required for equipment
Why would equipment diversity cause complexity when managing a network? - ✔✔Different
software must be used for different protocols (7)
Why do proprietary technologies cause complexity when managing networks? - ✔✔Some
equipment (router, switch, etc.) run on closed/proprietary software
Configuration interfaces vary as a result.
This causes issues for managing devices centrally. (7)
What is the simple idea of SDN that helps make networks more manageable? - ✔✔Separate
tasks into control plane and data plane. (7)
What are the 3 phases of history of SDN? - ✔✔1. Active networks
2. control plane and data plane separation
3. OpenFlow API and network operating systems (7)
What led to the growth of active networks, and what is their goal? - ✔✔1. the tediousness of
standardizing new protocols
,2. goal is to open up network control with an API that exposes resources and supports
*customization of functionalities* for subsets of packets passing through network nodes
(7)
Why do active networks conflict with idea of E2E? - ✔✔They require customization at
network nodes (not simplicity at network core)
(7)
What were the two types of programming models in active networking? How are thy different?
- ✔✔1. Capsule model
- carries in band data packets
- most used in relation to active networking
- code distribution ACROSS networks
- data plane
2. Programmable router/switch model
- out of band mechanisms
- decision-making a job for the NETWORK OPERATOR
- Difference is where the code to execute at the nodes was carried (7)
What are 4 tech developments that encouraged active networking? - ✔✔1. reduction in
computation cost (more processing can take place in the network)
2. advancement in programming languages
,3. advancement in rapid code compilation and formal methods
4. funding agencies promoted interoperability among projects
- necessary because there were no short-term use cases
(7)
What are 4 problems that encouraged active networking? - ✔✔1. developing network
services took a long time
2. third party interests to dynamically meeting needs of app and network conditions
3. researches needed a network for large-scale experiments
4. disadvantage of diverse models and vendors meant a desire for unified control over
middleboxes (7)
What are 3 contributions of SDN? - ✔✔1. programmable functions in network = lower
barrier to innovation
2. network virtualization and ability to demultiplex based on packet headers
3. vision of unified architecture for middlebox orchestration
(7)
Which plane are active networks associated with? - ✔✔Data plane (7)
, What plane do programmable functions in active networks focus on increasing
programmability, and why? - ✔✔- Data plane
- isolate experimental traffic from normal traffic (7)
What were some downfalls of active networking? - ✔✔- it was too ambitions
- didn't emphasize performance and security
- it didn't solve any short term problems
- end users need to be ale to write in java (7)
Did active network do anything for performance? Security? - ✔✔No (7)
What challenge did control and data plane separation tackle? - ✔✔Challenging how existing
routers and switches tightly integrated the data and control plane (7)
What were 4 tech developments that paved the way for control and data plane separation? -
✔✔1. packet forwarding (data plane) was implemented in hardware (separate from control
plane)
2. ISPs couldn't meet increasing demands for greater reliability and new services b/c of
increasing scope and size
3. servers have much more memory and processing resources - routing decisions could be done
on one server for one ISP network
4. open-source routing lowers barrier to creating prototypes of centralized routing controllers
(7)
Answers
What are 2 reasons computer networks are complex and difficult to manage that led to the
development of SDN? - ✔✔1. Diversity of network equipment
2. Proprietary technology required for equipment
Why would equipment diversity cause complexity when managing a network? - ✔✔Different
software must be used for different protocols (7)
Why do proprietary technologies cause complexity when managing networks? - ✔✔Some
equipment (router, switch, etc.) run on closed/proprietary software
Configuration interfaces vary as a result.
This causes issues for managing devices centrally. (7)
What is the simple idea of SDN that helps make networks more manageable? - ✔✔Separate
tasks into control plane and data plane. (7)
What are the 3 phases of history of SDN? - ✔✔1. Active networks
2. control plane and data plane separation
3. OpenFlow API and network operating systems (7)
What led to the growth of active networks, and what is their goal? - ✔✔1. the tediousness of
standardizing new protocols
,2. goal is to open up network control with an API that exposes resources and supports
*customization of functionalities* for subsets of packets passing through network nodes
(7)
Why do active networks conflict with idea of E2E? - ✔✔They require customization at
network nodes (not simplicity at network core)
(7)
What were the two types of programming models in active networking? How are thy different?
- ✔✔1. Capsule model
- carries in band data packets
- most used in relation to active networking
- code distribution ACROSS networks
- data plane
2. Programmable router/switch model
- out of band mechanisms
- decision-making a job for the NETWORK OPERATOR
- Difference is where the code to execute at the nodes was carried (7)
What are 4 tech developments that encouraged active networking? - ✔✔1. reduction in
computation cost (more processing can take place in the network)
2. advancement in programming languages
,3. advancement in rapid code compilation and formal methods
4. funding agencies promoted interoperability among projects
- necessary because there were no short-term use cases
(7)
What are 4 problems that encouraged active networking? - ✔✔1. developing network
services took a long time
2. third party interests to dynamically meeting needs of app and network conditions
3. researches needed a network for large-scale experiments
4. disadvantage of diverse models and vendors meant a desire for unified control over
middleboxes (7)
What are 3 contributions of SDN? - ✔✔1. programmable functions in network = lower
barrier to innovation
2. network virtualization and ability to demultiplex based on packet headers
3. vision of unified architecture for middlebox orchestration
(7)
Which plane are active networks associated with? - ✔✔Data plane (7)
, What plane do programmable functions in active networks focus on increasing
programmability, and why? - ✔✔- Data plane
- isolate experimental traffic from normal traffic (7)
What were some downfalls of active networking? - ✔✔- it was too ambitions
- didn't emphasize performance and security
- it didn't solve any short term problems
- end users need to be ale to write in java (7)
Did active network do anything for performance? Security? - ✔✔No (7)
What challenge did control and data plane separation tackle? - ✔✔Challenging how existing
routers and switches tightly integrated the data and control plane (7)
What were 4 tech developments that paved the way for control and data plane separation? -
✔✔1. packet forwarding (data plane) was implemented in hardware (separate from control
plane)
2. ISPs couldn't meet increasing demands for greater reliability and new services b/c of
increasing scope and size
3. servers have much more memory and processing resources - routing decisions could be done
on one server for one ISP network
4. open-source routing lowers barrier to creating prototypes of centralized routing controllers
(7)
