Describe Cisco VoIP implementations

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Questions derived from the 642-845 – Optimizing Converged Cisco Networks Cisco Self-Test Software Practice Test.


Objective: Describe Cisco VoIP implementations
SubObjective: Describe the functions and operations of a VoIP network (e.g., packetization, bandwidth considerations, CAC, etc.)


Item Number: 642-845.1.1.3
Single Answer, Multiple Choice


Which type of delay can vary significantly on a satellite communication link?



  1. Processing delay
  2. Queuing delay
  3. Serialization delay
  4. Transmission delay
  5. Propagation delay


E. Propagation delay


Propagation delay can significantly increase on a satellite communication link because communication satellites are situated at very high altitudes from source and destination base stations. Propagation delay is defined as the time it takes the signal to go from the source to the destination. It is based on the distance that the signal must travel.


Variation in other types of delays is comparatively smaller than Propagation delay because these are either device operating system or network interface dependent. Processing and queue delay will depend on operating system, CPU capacity, utilization, and free space in output queue. Serialization delay is network interface specific and remains small in comparison to progression delay.


Transmission delay is the time required to transmit a packet. It is determined by the size of the message and the bit rate of the media that is used for transmission.


Propagation Delay and Transmission Delay


Sources of Delay

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