Lesson 141
Wireless, Mobile & SDN
The shared medium & the programmable network
1:00Why the shared, lossy wireless medium changes everything — from collision avoidance and hidden terminals, through cellular handover and CDN edge caching, to software-defined networking.
By the end, you can
- Explain why the wireless medium is inherently shared and lossy, naming the three main impairments.
- Explain why Wi-Fi uses collision avoidance (CSMA/CA) rather than collision detection (CSMA/CD).
- Describe the CSMA/CA procedure, including why the backoff is random.
- Describe the hidden terminal problem and explain how RTS/CTS and the NAV solve it.
- Explain how cellular handover keeps a session alive as a device moves between towers, and state the approximate handover gap for 4G and 5G.
- Describe how a CDN reduces latency, distinguishing cache hits from cache misses.
- Distinguish the SDN control plane from the data plane, and explain what OpenFlow is used for.
- Define NFV and explain how it differs from traditional network appliance deployment.
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