Cisco 7931G - Unified IP Phone VoIP Administration Manual page 221

Chapter 9 Troubleshooting and Maintenance
Table 9-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary
Loopback condition
One-way audio
Peer to peer image distribution fails
Cisco Unified IP Phone 7931G Administration Guide for Cisco Unified Communications Manager 6.0
OL-12457-01
Explanation
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 appears in the switch console log:
HALF_DUX_COLLISION_EXCEED_THRESHOLD
To resolve this problem, re-enable the port from the switch.
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 configures.
If the peer to peer image distribution fails, the phone defaults to
using the TFTP server to download firmware. Access the log
messages stored on the remote logging machine to help debug
the peer to peer image distribution feature.
These log messages are different than the log messages
Note
that are sent to the phone log.
General Troubleshooting Tips
9-17