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cisco troubleshooting_tips - Tips from Troubleshooting...

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Tips from Troubleshooting Cisco IP Telephony authors Paul Giralt, Anne Smith, and Addis Hallmark CallManager Tip Time Synchronization Time synchronization is simply making sure that all the participating CallManager servers and network devices have the same exact time. All the CallManager servers can be time-synched using the Network Time Protocol (NTP). When you synchronize the time on all involved servers, all the trace files are time stamped the same. When trace files are collected for analysis, you can follow the true series of call processing events with accuracy. In addition to CallManager servers, you should ensure all network devices such as switches, routers, and voice gateways are synchronized to the same time source as the CallManager servers. This ensures consistent timestamps regardless of which device you are looking at. IP Phone Tips IP Phone Won’t Register Skinny client registration problems are usually caused by a misconfiguration on CallManager, the DHCP server, one or more network devices, or the IP phone itself. Follow these steps when you encounter an IP phone that doesn’t register properly with CallManager: Step 1 Check for inline power issues. Step 2 Check IP addressing and DHCP. Step 3 Check for IP network connectivity. Step 4 Check for Trivial File Transfer Protocol (TFTP) problems. Step 5 Check for CallManager issues. If you have checked for inline power issues and verified that the IP Phone has the correct information, but it still doesn’t register, you need to do some additional investigating. Here are some common reasons why registration fails at this point: The CallManager service is not running. The IP Phone can’t reach CallManager. Try to ping the IP Phone from the CallManager server it is trying to register. This will confirm bi-directional IP connectivity. If NAT, firewalls, or access lists are in use, be sure to check there as well to make sure that traffic is not being blocked, thus preventing proper communication. Skinny devices use TCP port 2000 to register with CallManager. If the IP Phone must resolve the CallManager name to register, a failure could occur if the DNS server is inaccessible or the DNS entry is incorrect. Generally it is a good idea
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not to rely on DNS at all. To use IP addresses instead of DNS names, configure the servers in the cluster by IP address in CallManager Administration ( System > Server ). The IP Phone firmware load specified by CallManager is not in the TFTP path. If the IP Phone load currently running on the phone is not compatible with the CallManager the phone is trying to register to, the registration might fail. Ensure that the IP Phone is running the firmware version specified in CallManager Administration ( System > Device Defaults ). If the IP Phone has never been entered into the CallManager database via CallManager
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cisco troubleshooting_tips - Tips from Troubleshooting...

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