Cisco Systems 8.6 manual Identifying Intermittent Network Outages, Verifying Dhcp Settings

Chapter 9 Troubleshooting and Maintenance

Cisco Unified IP Phone Resets Unexpectedly

Identifying Intermittent Network Outages

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.

Verifying DHCP Settings

The following suggestions can help you determine if the phone has been properly configured to use DHCP:

1.Verify that you have properly configured the phone to use DHCP. See Network Configuration Menu, page 4-5for more information.

2.Verify that the DHCP server has been set up properly.

3.Verify the DHCP lease duration. We recommend that you set the lease duration to 8 days.

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 renewal is denied, forcing the phone to restart and request a new IP address from the DHCP server.

Checking Static IP Address Settings

If the phone has been assigned a static IP address, verify that you have entered the correct settings. See Network Configuration Menu, page 4-5for more information.

Verifying the Voice VLAN Configuration

If the Cisco Unified IP Phone appears to reset during heavy network usage (for example, following extensive web surfing on a computer connected to the same switch as the phone), it is likely that you do not have a voice VLAN configured.

Isolating the phones on a separate auxiliary VLAN increases the quality of the voice traffic. See Understanding How the Cisco Unified IP Phones Interact with the VLAN, page 2-2for details.

Verifying that the Phones Have Not Been Intentionally Reset

If you are not the only administrator with access to Cisco Unified Communications Manager, you should verify that no one else has intentionally reset the phones.

You can check whether a Cisco Unified IP Phone received a command from Cisco Unified Communications Manager to reset by pressing the Settings button on the phone and choosing Status > Network Statistics. If the phone was recently reset one of these messages appears:

•Reset-Reset—Phone received a Reset/Reset request from Cisco Unified Communications Manager Administration.

Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.6 (SCCP and SIP)

OL-23091-01 9-7