Verifying Physical Connection; Identifying Intermittent Network Outages; Verifying Dhcp Settings - Cisco CP-3911 - Unified SIP Phone 3911 VoIP Administration Manual

Chapter 7 Troubleshooting and Maintenance

Verifying Physical Connection

Identifying Intermittent Network Outages

Verifying DHCP Settings

Cisco Unified SIP Phone 3911 Administration Guide for Cisco Unified Communications Manager
OL-14029-01
Verify that the Ethernet connection to which the Cisco Unified IP Phone is
connected is up. For example, check if the particular port or switch to which the
phone is connected is down.
Intermittent network outages affect data and voice traffic differently. Your
network might have been experiencing intermittent outages without detection. If
so, data traffic can resend lost packets and verify that packets are received and
transmitted. However, voice traffic cannot recapture lost packets. Rather than
retransmitting a lost network connection, the phone resets and attempts to
reconnect its network connection.
If you are experiencing problems with the voice network, you should investigate
whether an existing problem is simply being exposed.
The following suggestions can help you determine if the phone has been properly
configured to use DHCP:
Verify that you have properly configured the phone to use DHCP. See the
1.
"Configuring Network Settings" section on page 4-3
Verify that the DHCP server has been set up properly.
2.
Verify the DHCP lease duration. Cisco recommends that you set it to 8 days.
3.
Cisco Unified IP Phones send messages with request type 151 to renew their
DHCP address leases. If the DHCP server expects messages with request type
150, the lease will be denied, forcing the phone to restart and request a new
IP address from the DHCP server.
Cisco Unified IP Phone Resets Unexpectedly
for more information.
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