Online Access Free 642-437 Practice Test

DRAG DROP
Drag the delay type on the left and drop it on the correct description on the right.

Correct Answer:

Explanation:

Processing Delay: Coder delay is the time taken by the digital signal processor (DSP) to compress a block of PCM samples. This is also called processing delay (n). This delay varies with the voice coder used and processor speed. Serialization Delay: Serialization delay (n) is the fixed delay required to clock a voice or data frame onto the network interface. It is directly related to the clock rate on the trunk. Dejitter Buffer: Because speech is a constant bit-rate service, the jitter from all the variable delays must be removed before the signal leaves the network. In Cisco router/gateways this is accomplished with a de-jitter (n) buffer at the far-end (receiving) router/gateway. The de-jitter buffer transforms the variable delay into a fixed delay. It holds the first sample received for a period of time before it plays it out. This holding period is known as the initial play out delay. DSP Delay: The time the packet spends inside the DSP is known as DSP Delay. Sampling, Encoding, Decoding etc. takes place inside the DSP. Queuing Delay: After the compressed voice payload is built, a header is added and the frame is queued for transmission on the network connection. Voice needs to have absolute priority in the router/gateway. Therefore, a voice frame must only wait for either a data frame that already plays out, or for other voice frames ahead of it. Essentially the voice frame waits for the serialization delay of any preceding frames in the output queue. Queuing delay (Bn) is a variable delay and is dependent on the trunk speed and the state of the queue. There are random elements associated with the queuing delay. Propagation Delay: Caused by the length a signal must travel via light in fiber or electrical impulse in copper-based networks
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_white_paper09186a00800a8993.shtml

Which three Cisco IOS commands are required to configure a voice gateway as a DHCP server to support a data subnet with the IP address of 10.1.30.0/24 and a default gateway of 10.1.30.1/24? (Choose three.)

• A.ip dhcp pool
• B.default-router 10.1.30.1
• C.network 10.1.30.1/24
• D.ip dhcp pool data
• E.network 10.1.30.0 255.255.255.0
• F.subnet 10.1.30.1 255.255.255.0
• G.default-gw 10.1.30.1/24

Which of these is assigned to a phone or line to implement calling privileges?

• A.route list
• B.partition
• C.calling search space
• D.class of service

In a voice gateway, the configured codec complexity of the DSPs on a voice card can be changed. What is the impact on the DSPs if high codec complexity is configured?

• A.With higher codec complexity, more calls can be processed.
• B.The DSP will process codecs that support high complexity transparently and shift to flex mode for those codecs that are not high complexity.
• C.The codec complexity affects call density, which is the number of calls that are reconciled on the DSPs. This results in lower call density when high complexity is configured.
• D.Lower codec complexity supports the fewest number of voice channels, provided that the lower complexity is compatible with the particular codecs that are in use.

How does Packet Loss Concealment improve voice quality?

• A.Packet Loss Concealment will compensate for packet loss rates between 1 and 5 percent by generating a reasonable replacement packet to improve the voice quality.
• B.Packet Loss Concealment will buffer 20 to 50 ms of a voice stream to minimize lost or out-oforder voice packets.
• C.Packet Loss Concealment intelligently analyzes missing packets and generates a reasonable replacement packet to improve the voice quality.
• D.Cisco Packet Loss Concealment technology decreases the voice sampling rate to 10 ms of the voice payload to smooth gaps in the voice stream.