350-801 · Question #378
350-801 Question #378: Real Exam Question with Answer & Explanation
The correct answer is C: The satellite is 35,786 km (22,236 miles) above sea level (from the equator), so an engineer will. When deploying voice and video applications over geostationary satellite routes, it is often impossible to comply with ITU-T G.114 latency requirements due to the inherent physical distance. The correct answer highlights this fundamental limitation of satellite communication.
Question
How does an administrator ensure compliance with ITU-T G.114 latency requirements when deploying voice and video applications over routes that include a geostationary satellite?
Options
- AFor voice and video applications over satellite, Cisco recommends using WAN optimization
- BUsing G.729 voice codec Instead of G.711 voice codec will reduce the packet size and the
- CThe satellite is 35,786 km (22,236 miles) above sea level (from the equator), so an engineer will
- DThe application will work because it will be below the recommenced latency requirement If an
Explanation
When deploying voice and video applications over geostationary satellite routes, it is often impossible to comply with ITU-T G.114 latency requirements due to the inherent physical distance. The correct answer highlights this fundamental limitation of satellite communication.
Approach. The geostationary satellite's high altitude (35,786 km or 22,236 miles) causes significant signal propagation delay, resulting in a one-way latency of at least 250-270ms for a single satellite hop. This inherent physical delay makes it practically impossible to meet the ITU-T G.114 recommendation of 150ms one-way latency for good voice quality when using a geostationary satellite.
Common mistakes.
- A. WAN optimization can improve bandwidth efficiency and some application-level latency, but it cannot overcome the fundamental speed-of-light propagation delay caused by the immense distance to a geostationary satellite.
- B. Using a G.729 codec instead of G.711 reduces bandwidth usage and packet size but does not significantly impact the propagation delay introduced by the physical distance to the geostationary satellite.
- D. A single geostationary satellite hop inherently introduces a one-way latency of 250ms or more, which already exceeds the recommended ITU-T G.114 latency of 150ms, making compliance unachievable.
Concept tested. Satellite latency limitations for real-time applications
Topics
Community Discussion
No community discussion yet for this question.