CCNA VOIP Ch 15
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You are planning a structured troubleshooting approach for an IP phone registration issue. You just defined the problem; what is our next step?
a. Consider the possibilities.
b. Gather the facts.
c. Create an action plan.
d. Implement an action plan.
- define problem
- gather facts
- consider possibilities
- create action plan
- implement action plan
- observe results
- utilize process
You just finished resolving an outage issue in the voice network. Which of the following should you do as a follow-up measure? (choose 3)
a. Reboot the devices to ensure the issue does not reappear.
b. Document the solution.
c. Document the root cause of the issue.
d. Document the changes made to the system.
e. Document the next change window for follow-up.
b c d
You are troubleshooting an IP phone registration issue. You verify that the IP phone is receiving an IP address with Option 150 from the DHCP server. What should the phone do next after this point?
a. Reboot with a new configuration.
b. Contact the TFTP server.
c. Register with the CME router.
d. Update its firmware.
A cisco IP phone is plugged into an Ethernet wall jack. The phone does not resopnd to the connection. What shouyld your first area of troubleshooting be for this situation?
a. Verify that the voice VLAN is assigned to the port.
b. Enable CDP on the interface.
c. Verify PoE configuration.
d. Ensure that you are using Cat 6 Ethernet cable.
You believe one of your Cisco IP Phones has not been assigned to the correct voice VLAN. What symptom is typically seen when this occurs?
a. the ip phone has unforeseen call restrictions or permissions.
b. the ip phone displays "invalid VLAN" on the screen.
c. the ip phone continually reboots.
d. the PC attached to the IP phone loses network connectivity.
After a Cisco IP phone determines its voice VLAN configuration via CDP, what does it do?
a. the phone reboots in the new VLAN.
b. the phone sends out a DHCP request tagged with the voice VLAN number.
c. the phone sends out an untagged DHCP request.
d. the phone queries for a TFTP server in the new VLAN.
An IP phone boots and displays "Registration Rejected" on the screen. What is the most likely cause of the issue?
a. the CME router has no appropriate ephone config.
b. an ACL is blocking access to the CME router.
c. the TFTP server is not serving the correct files.
d. the MAC address of the phone is in the disallow list.
What command can you enter to watch CME process calls as digits are dialed?
a. show dialpeer voice
b. debug dialpeer voice
c. debug voip dialpeer
d. debug voice dialed
What is the one-way delay requirement Cisco recommends to achieve high-quality voice calls?
a. 100 ms
b. 150 ms
c. 200 ms
d. 250 ms
What command can you use to verify QoS operations and packet statistics on a specific interface of your CME router?
a. show run
b. show qos interface
c. show service-policy interface
d. show policy-map interface
What are the 7 troubleshooting steps as defined by CIsco?
- Define problem
- Gather facts
- Consider possibilities
- Create action plan
- Implement action plan
- Observe results
- Utilize process.
if problem is resolved: Document facts
See pg 400 for details
Detail the boot up process for an IP phone.
1. 802.3af PoE sends voltage, detects device and supplies power to the line.
2. Switch delivers voice VLAN info via CDP.
3. IP phone does DHCP dance with DHCP server, DHCP adds option 150 (TFTP server IP address).
4. Phone contacts TFTP server and gets config file and firmware.
5. Based on config file, phone registers with call precessing server(s). 1, 2, 3, repeat in big deployments. CME rtr in smaller deployments.
What are the paramenters for high quality VOIP calls?
End to End (one-way) delay
Jitter (variation in delay)
End-to-end delay 150 ms or less
Jitter 30 ms or less
Packet loss 1% or less
What is the average BW per call for g.711 and g.729a?
codec packetization interval BW per call
- G.711 20 ms 80 kbps
- G.711 30 ms 74 kbps
- G.729a 20 ms 24 kbps
- G.729a 30 ms 19 kbps
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