Before you set up and run a Diagnosis, review the following configuration tips and perform any that are applicable to your VoIP environment. Performing some or all of these tips can improve the quality of data that you receive from a Diagnosis.
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Tip |
Description |
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Supply your SNMP permissions information |
Vivinet Diagnostics supports SNMP versions 1, 2, and 3. SNMP permissions allow Vivinet Diagnostics to gather information from SNMP-enabled network devices. Read/write authorization for SNMP versions 1 and 2 is required for running Cisco IOS IP SLA tests on routers and to retrieve QoS configuration information. For other types of queries, such as queries of CallManagers, read-only access is adequate. For more information, see Section 3.5.1, Configuring SNMP Permissions. |
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Ensure Diagnoses can run through firewalls |
For each Diagnosis, Vivinet Diagnostics attempts to perform a traceroute test to find the exact path VoIP packets are taking. A firewall could prevent the packets from making some hops, however. To ensure Vivinet Diagnostics works properly with a firewall on your network, select the port Vivinet Diagnostics should use for the call (or RTP) traffic it sends. Remember, RTP traffic uses even-numbered ports. For more information, see Section 4.1, Running a Diagnosis Through a Firewall. |
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Ensure IOS IP SLA is properly configured |
The Cisco IOS IP SLA allows network performance monitoring between a Cisco router and a remote device, such as another Cisco router or an IP host. IOS IP SLA or the Monitor Responder support running jitter and delay tests on many Cisco routers. In cases where the Target Devices for the Diagnosis are phones (instead of Performance Endpoints), Vivinet Diagnostics gathers data from IOS IP SLA tests to diagnose the problem. Two routers, each running IOS IP SLA, are required (one is a sender, the other a responder). To test jitter, the responder must be enabled. To determine whether IOS IP SLA is enabled on a router, issue the following command: show ip sla monitor responder To enable IOS IP SLA, issue the following commands: configure terminal ip sla monitor responder If you are running a Diagnosis between Nortel phones in a network that uses Cisco routers, ensure you have enabled IOS IP SLA. Vivinet Diagnostics looks first to the Nortel phones and then to the endpoints for data. Should either source not provide information, Vivinet Diagnostics gathers data from IOS IP SLA. |
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Enable your Console’s IP address on SNMP devices |
During a Diagnosis, Vivinet Diagnostics communicates with the SNMP-enabled devices on your network. The Vivinet Diagnostics Console address must be included in any access list that controls access to these devices. To determine whether the Console’s IP address is included in a device’s access list, issue the following command: show access-list To add an IP address to a device’s access list, issue the following command: configure access-list |
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Configure CallManager to collect CDRs and CMRs |
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Configure SNMP on CallManagers |
On each CallManager computer, ensure the SNMP service is running and configured properly. From Administrative Tools, double-click Services. Ensure the SNMP service is set to “Automatic” and is running. Right-click the service and select Properties. In the Service Properties dialog box, select Applications on the Agent tab. Add a read-only community string on the Security tab. Then add this community string to Vivinet Diagnostics. For more information, see Section 3.5.1, Configuring SNMP Permissions. |
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Ensure CDP is enabled |
CDP enables the discovery of Cisco devices, particularly Layer 2 devices (switches). Because switches constitute potential bottlenecks for VoIP traffic, information about their location and utilization is important for a Diagnosis. Do not disable CDP on your devices before you run a Diagnosis. For more information, see Section 1.3, Cisco Discovery Protocol. |
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Ensure ports 443 and 80 are available on CallManager server |
Vivinet Diagnostics always attempts to use the Secure Sockets Layer (SSL) protocol through port 443, the standard SSL Internet port, when requesting CallManager data. If the attempt fails, Vivinet Diagnostics uses the HTTP protocol through port 80, the standard Internet port. |
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Ensure SONMP is enabled |
SONMP is a Layer 2 protocol that supplies topology information about devices that also speak SONMP, mostly switches and hubs. SONMP is implemented in Nortel devices. Layer 2 devices for which SONMP is not enabled are invisible to a diagnostic test or can bring the test to a halt. SONMP is enabled by default on Nortel devices. If you disabled it on any piece of Nortel equipment, re-enable it. For more information, see Section 1.5, Nortel SONMP or NDP. |
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Ensure LLDP TLVs are enabled |
LLDP data is not saved to a device’s MIB unless the Management TLVs are enabled. For more information, see Section 1.6, Link Layer Discovery Protocol. |
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Configure the actual speed on serial interfaces |
To diagnose a problem involving serial interfaces, including frame relay and serial links, Vivinet Diagnostics needs to determine the bandwidth utilization on these links. However, device MIBs for these interfaces often provide the wrong speed attribute, showing the links’ theoretical maximum speed instead of the actual speed at which they are running. Diagnoses on serial links will be more accurate if you ensure the correct (that is, operating) speed is configured for the bandwidth parameter on serial interfaces. That way, the SNMP MIB variable ifSpeed will reflect the correct value. |
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Synchronize router clocks |
In order for Vivinet Diagnostics to retrieve delay statistics on VoIP calls using Cisco IOS IP SLA, the clocks on all the routers must be synchronized with each other. To synchronize router clocks, issue the following command (from router configuration):
ntp server <server>
where <server> is the IP address or DNS hostname of the Network Time Protocol (NTP) server on the network. |
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Ensure ICMP is enabled |
Vivinet Diagnostics runs some diagnoses by sending out Internet Control Message Protocol (ICMP) packets to gather information at each router hop. If a router’s ICMP is disabled, it cannot provide pertinent information for a Diagnosis. Refer to your device documentation for information about enabling ICMP. |
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Configure thresholds. |
As an optional step, configure thresholds that help Vivinet Diagnostics determine whether a network condition should be reported as an issue. For more information, see Section 3.5.5, Setting Thresholds. |