Lab Exercise: Voice Port Configuration

In this lab, you will configure and test router R1's FXS port using the topology you constructed in the lab exercise for Chapter 2, "Analog and Digital Voice Connections." Recall that an FXS port allows you to connect end stations, such as analog phones, fax machines, and modems, into a voice-enabled router.

Figure 3-19 illustrates the lab's physical topology and IP addressing.

Figure 3-19. Lab Topology

Task 1: Configure FXS Port Parameters

In this task, you will issue commands to configure various parameters on an FXS port.

Complete these steps:


Enter voice port configuration mode for the FXS port on router R1.


To ensure the appropriate signaling type on this voice port, configure the signaling to the default value of loopstart.


Assume the analog phone connected to this voice port is located in one of several adjoining cubicles and you wish to create a distinctive ring for this phone so that the phone's user can distinguish their phone's ringing pattern from other phones' ringing patterns. Create a distinctive ringing pattern that causes the analog phone to ring for 5 seconds, be silent for 1 second, and then repeat this pattern. To make sure this change takes effect, shut down and then bring up the voice port, using the shutdown command, followed by the no shutdown command.


Assume that several thousand feet of cable separate the analog phone from the FXS port, and as a result, some electrical capacitance has built up in the line. This capacitance can lead to an impedance mismatch, thus causing echo. To help counteract this capacitance, change the impedance value of the voice port from the default value of 600r (that is, 600 purely resistive ohms) to 600c (that is, 600 ohms of impedance that contains both a resistive and a capacitive component).


At this point, you have not configured your voice-enabled routers with call routing intelligence. Therefore, you cannot place a call between the two analog phones. However, the parameters you configured in this lab will be in effect at the completion of the lab exercise for Chapter 4.

Task 2: Exercise Verification

In this task, you will verify the parameters you configured are in effect and that the FXS port is functioning properly.

Complete these steps:


To verify that the appropriate signaling, ring cadence, and impedance settings are applied to R1's FXS port, use the show voice port port_id command to view the port settings.


To verify that the voice port is functioning, lift the handset of the attached analog phone. You should hear dial tone. If you do not hear dial tone, you might need to administratively bring up the port with the no shutdown command.


To verify that the voice port can send a ringing signal at an appropriate voltage and frequency as to alert the attached analog phone, enter the test voice port port_id relay ring on command, followed by the test voice port port_id relay ring disable command.

Suggested Solution

Although your physical hardware might differ, Example 3-9 offers one solution to the preceding exercise.

Example 3-9. Router R1's Configuration

 R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1(config)#voice-port 1/1 R1(config-voiceport)#signal loopstart R1(config-voiceport)#ring cadence define 50 10 R1(config-voiceport)#shutdown R1(config-voiceport)#no shutdown R1(config-voiceport)#impedance 600c R1(config-voiceport)#end 

The results of the show voice port port_id command, issued on router R1, should be similar to the output shown in Example 3-10. Note that the shaded lines in the output reflect the parameters configured in this exercise

Example 3-10. Router R1's show voice port 1/1 Output

 R1#show voice port 1/1 FXS 1/1 Slot is 1, Port is 1  Type of VoicePort is FXS  Operation State is DORMANT  Administrative State is UP  No Interface Down Failure  Description is not set  Noise Regeneration is enabled  Non Linear Processing is enabled  Non Linear Mute is disabled  Non Linear Threshold is -21 dB  Music On Hold Threshold is Set to -38 dBm  In Gain is Set to 0 dB  Out Attenuation is Set to 0 dB  Echo Cancellation is enabled  Echo Cancellation NLP mute is disabled  Echo Cancellation NLP threshold is -21 dB  Echo Cancel Coverage is set to 64 ms  Echo Cancel worst case ERL is set to 6 dB  Playout-delay Mode is set to adaptive  Playout-delay Nominal is set to 60 ms  Playout-delay Maximum is set to 200 ms  Playout-delay Minimum mode is set to default, value 40 ms  Playout-delay Fax is set to 300 ms  Connection Mode is normal  Connection Number is not set  Initial Time Out is set to 10 s  Interdigit Time Out is set to 10 s  Call Disconnect Time Out is set to 60 s  Supervisory Disconnect Time Out is set to 750 ms  Ringing Time Out is set to 180 s  Wait Release Time Out is set to 30 s  Companding Type is u-law   Coder Type is g729ar8  Voice Activity Detection is enabled  Nominal Playout Delay is 60 milliseconds  Maximum Playout Delay is 200 milliseconds  Region Tone is set for US  Analog Info Follows:  Currently processing none  Maintenance Mode Set to None (not in mtc mode)  Number of signaling protocol errors are 0  Impedance is set to 600c Ohm  Analog interface A-D gain offset = -3.0 dB  Analog interface D-A gain offset = -3.0 dB  FXS idle voltage set to low  Station name None, Station number None  Translation profile (Incoming):  Translation profile (Outgoing):  Voice card specific Info Follows:  Signal Type is loopStart  Ring Frequency is 20 Hz  Hook Status is On Hook  Ring Active Status is inactive  Ring Ground Status is inactive  Tip Ground Status is active  Digit Duration Timing is set to 100 ms  InterDigit Duration Timing is set to 100 ms  Hookflash-in Timing is set to 1000 ms  Hookflash-out Timing is set to 400 ms  No disconnect acknowledge  Ring Cadence is User defined                                  Ring Cadence are [50 10] * 100 msec                           Ringer Equivalence Number is set to 1  InterDigit Pulse Duration Timing is set to 500 ms 

Cisco Voice over IP Cvoice (c) Authorized Self-study Guide
Cisco Voice over IP (CVoice) (Authorized Self-Study Guide) (2nd Edition)
ISBN: 1587052628
EAN: 2147483647
Year: 2006
Pages: 111
Authors: Kevin Wallace

Similar book on Amazon © 2008-2017.
If you may any questions please contact us: