Cisco Systems OL-19025-01 manual Halfduxcollisionexceedthreshold

Chapter 9 Troubleshooting and Maintenance

General Troubleshooting Tips

Table 9-1	Cisco Unified IP Phone Troubleshooting (continued)
Summary		Explanation
Changing the telephone configuration.		By default, the network configuration options are locked to prevent users from
		making changes that could impact their network connectivity. You must unlock
		the network configuration options before you can configure them. See the
		“Unlocking and Locking Options” section on page 4-3for details.
Phone resetting.		The phone resets when it loses contact with the Cisco Unified Communications
		Manager software. This lost connection can be due to any network connectivity
		disruption, including cable breaks, switch outages, and switch reboots.
LCD display issues.		If the display appears to have rolling lines or a wavy pattern, it might be
		interacting with certain types of older fluorescent lights in the building.
		Moving the phone away from the lights, or replacing the lights, should resolve
		the problem.
Dual-Tone Multi-Frequency (DTMF)		When you are on a call that requires keypad input, if you press the keys too
delay.		quickly, some of them might not be recognized.
Codec mismatch between the phone and		The RxType and the TxType statistics show the codec that is being used for a
another device.		conversation between this Cisco Unified IP phone and the other device. The
		values of these statistics should match. If they do not, verify that the other
		device can handle the codec conversation, or that a transcoder is in place to
		handle the service.
		See the “Call Statistics Screen” section on page 7-8for information about
		displaying these statistics.
Sound sample mismatch between the		The RxSize and the TxSize statistics show the size of the voice packets that are
phone and another device.		being used in a conversation between this Cisco Unified IP phone and the other
		device. The values of these statistics should match.
		See the “Call Statistics Screen” section on page 7-8for information about
		displaying these statistics.
Gaps in voice calls.		Check the AvgJtr and the MaxJtr statistics. A large variance between these
		statistics might indicate a problem with jitter on the network or periodic high
		rates of network activity.
		See the “Call Statistics Screen” section on page 7-8for information about
		displaying these statistics.
Loopback condition.		A loopback condition can occur when the following conditions are met:
		• The SW Port Configuration option in the Network Configuration menu on
		the phone is set to 10 Half
		(10-BaseT / half duplex)
		• The phone receives power from an external power supply
		• The phone is powered down (the power supply is disconnected)
		In this case, the switch port on the phone can become disabled and the
		following message will appear in the switch console log:
		HALF_DUX_COLLISION_EXCEED_THRESHOLD
		To resolve this problem, re-enable the port from the switch.
One-way audio.		When at least one person in a call does not receive audio, IP connectivity
		between phones is not established. Check the configurations in routers and
		switches to ensure that IP connectivity is properly configured.

Cisco Unified IP Phone 6921, 6941, and 6961 Administration Guide for Cisco Unified Communications Manager 7.1 (SCCP)

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