Chapter 14. Troubleshooting and frequently asked questions

Table of Contents

14.1. Troubleshooting sFlowTrend-Pro
14.1.1. Installation problems
14.1.1.1. sFlowTrend-Pro requires the Java Run-time Environment (JRE) v7.0
14.1.2. No switches are listed in the Switch selector
14.1.3. When I select a switch in the Network, Top N tab, the chart is blank
14.1.4. When I select a switch in the Network Interfaces tab, the table is empty
14.1.5. When I select a switch in the Network Interfaces tab, the table rows have no counter values.
14.1.6. sFlowTrend-Pro is not receiving sFlow from a switch or host
14.1.7. sFlowTrend-Pro cannot communicate with the switch using SNMP
14.2. Frequently asked questions
14.2.1. After I select a switch to monitor, why does nothing happen?
14.2.2. When I start sFlowTrend-Pro, why do I get an error message "Cannot open UDP port 6343"?
14.2.3. Why are most of the bars in a Top N chart colored grey?
14.2.4. What firewall requirements does sFlowTrend-Pro have?
14.2.5. How do I change the time for which sFlowTrend-Pro stores data?

14.1. Troubleshooting sFlowTrend-Pro

14.1.1. Installation problems

14.1.1.1. sFlowTrend-Pro requires the Java Run-time Environment (JRE) v7.0

sFlowTrend-Pro is written in Java, and needs a minimum of Java v7.0. Java must be installed before installing sFlowTrend-Pro. Also, in the case of other installation problems, it is often easiest just to re-install the Java JRE.

The JRE is available from www.java.com

14.1.2. No switches are listed in the Switch selector

If there are no switches listed in the Switch selector in the Network and Threshold tabs, all the charts in the Dashboard tab show No data and the Activity LED is not flashing then sFlowTrend-Pro is not receiving sFlow data. The Status bar should also show Configure switches/routers to monitor.

You must first configure your switches to send sFlow, see Appendix A, Configuring switches to send sFlow. If there are still no switches listed see Section 14.1.6, “sFlowTrend-Pro is not receiving sFlow from a switch or host”.

14.1.3. When I select a switch in the Network, Top N tab, the chart is blank

If you select a switch using the Switch selector in the Network Top N tab and the chart is blank, sFlowTrend-Pro has not received sFlow data that matches the criteria specified by the current settings in the Top N tab.

  • If the Interface selector does not include individual interfaces, sFlowTrend-Pro is not receiving sFlow data from the switch. First ensure that the selected switch is enabled (see Section 4.6, “Selecting a switch”. If the switch is enabled see Section 14.1.6, “sFlowTrend-Pro is not receiving sFlow from a switch or host”.

  • If there are interfaces listed in the Interface selector, sFlowTrend-Pro has received sFlow data from the switch, but possibly not for the combination of the currently selected interface, chart, time, and filter. First make sure that the selected switch is enabled so that the Status bar indicates that the switch is not disabled (see Section 13.3, “Configuring agents in sFlowTrend-Pro ). Then change the settings in the control bar as follows:

    • Charts: Top sources

    • Interfaces: All (this selection is only available if you are viewing a top N traffic trend chart).

    • Time: Last hour

    • Filter is disabled

    For more information on settings in the Network tab see Chapter 4, Network.

    Now wait for the Progress indicator to reach 100%.

    If the Top sources chart is still not showing data, then sFlowTrend-Pro is not receiving sFlow from the switch, see Section 14.1.6, “sFlowTrend-Pro is not receiving sFlow from a switch or host”.

    If you are now seeing data in the Top sources chart, sFlowTrend-Pro is receiving sFlow data from the switch. To understand which interfaces are reporting on traffic, change to the Interfaces tab and click on the Unicasts/s column heading until the table is sorted so that rows are listed with the interface showing the highest unicasts/s listed first. If there are interfaces listed in table but there are no counter values, wait for the Progress indicator to reach 100% again (see Section 4.1, “Interfaces” for more information on the Interfaces tab). Then click on the chart button associated with first row. You will now be taken to the Counters tab with the interface with the most unicast/s selected.

14.1.4. When I select a switch in the Network Interfaces tab, the table is empty

If you select a switch using the Switch selector in the Network Interfaces tab and the table remains empty even after the Progress indicator has reached 100%, sFlowTrend-Pro is not receiving sFlow from that switch.

If Status bar message indicates that the switch is disabled, enable the switch (see Section 13.3, “Configuring agents in sFlowTrend-Pro ).

If the switch is enabled, then see Section 14.1.6, “sFlowTrend-Pro is not receiving sFlow from a switch or host”.

14.1.5. When I select a switch in the Network Interfaces tab, the table rows have no counter values.

If you select a switch using the Switch selector in the Network Interfaces tab and the table includes rows for the interfaces but the interface counter columns show "-" even after the Progress indicator has reached 100%, twice, sFlowTrend-Pro is receiving sFlow from the switch but the sFlow data does not include interface counters. Check that the switch is configured to export interface counters (see Appendix A, Configuring switches to send sFlow).

14.1.6. sFlowTrend-Pro is not receiving sFlow from a switch or host

If the switch has been configured using the CLI to send sFlow, follow the steps below:

  1. Ensure that the switch is using the correct IP address and UDP port used by the host running sFlowTrend-Pro. To view and configure the IP address and UDP port used by sFlowTrend-Pro see Section 13.2.2, “sFlow configuration”.

  2. Ensure that there are no host or network firewalls between the switch and sFlowTrend-Pro that are blocking the sFlow packets.

  3. There may be insufficient traffic flowing through the switch for sFlow packets to be generated using the currently configured sampling rate. Try configuring the switch to sample more frequently. See Appendix C, Recommended sampling rates for recommended sampling rates.

If the host is running the sFlow agent, follow the steps below:

  1. Ensure that the host is using the correct IP address and UDP port used by the host running sFlowTrend-Pro. To view and configure the IP address and UDP port used by sFlowTrend-Pro see Section 13.2.2, “sFlow configuration”.

  2. Ensure that there are no host or network firewalls between the host and sFlowTrend-Pro that are blocking the sFlow packets.

  3. Check that the sFlow agent is running on the host. For more information on configuring the host agent, see Appendix B, Configuring hosts to send sFlow.

If sFlowTrend-Pro is to use SNMP to configure the switch to send sFlow, follow the steps below:

  1. Make sure that the switch has been added to sFlowTrend-Pro, see Section 13.3.1, “Adding a switch configured via SNMP” and that the correct SNMP v2 or SNMP v3 settings, which allow write access to the sFlow MIB, have been specified. Some additional configuration of the switch may be necessary to allow it to accept SNMP sets from the host running sFlowTrend-Pro, for example, see Section A.1.1, “Configuring ProCurve switches to allow sFlow configuration via SNMP”.

  2. Use Tools Configure agents and view the status details for the switch either by moving the mouse over the status color indicator to activate the tooltip or by clicking on the edit button. If the status indicates that the switch is not sending sFlow use the additional status message to identify the problem:

    No SNMP
    sFlowTrend-Pro cannot communicate with the switch using SNMP. Verify that the sFlowTrend-Pro is using the correct SNMP v2 or SNMP v3 settings and that there are no firewalls in the network or on the host that are blocking SNMP. See Section 14.1.7, “sFlowTrend-Pro cannot communicate with the switch using SNMP” for more diagnostics.
    Cannot configure sFlow with SNMP - SNMP write access denied
    sFlowTrend-Pro is not using the correct SNMP v2 read/write community or SNMP v3 settings or the switch is not configured to allow SNMP set from the system running sFlowTrend-Pro.
    Cannot configure sFlow with SNMP - no sFlow MIB
    The switch cannot be configured via SNMP to send sFlow. Instead, you must use the switch CLI to configure sFlow (see Appendix A, Configuring switches to send sFlow).
    Already in use
    Another application has already configured this switch to send sFlow and there are no additional resources to send sFlow to sFlowTrend-Pro as well. Disable the other application so that the switch can be configured by sFlowTrend-Pro. You can identify the other applications which have already configured the switch by using the edit button. The Additional switch details section, under Other owners lists the IP addresses of the other systems which have configured the switch, together with a description of the application. Alternatively, you can configure sFlowTrend-Pro so that it removes the other application's claim on the switch and replaces it with its own (see Section 15.1, “Server custom configuration settings”, sflowtrend.useForce).

  3. If the status indicates that sFlow has been successfully configured, there may be insufficient traffic flowing through the switch for sFlow packets to be generated using the currently configured sampling rate. Try changing the sFlowTrend-Pro configuration so that the switch to is configured to sample more frequently (see Section 15.1, “Server custom configuration settings”).

14.1.7. sFlowTrend-Pro cannot communicate with the switch using SNMP

If sFlowTrend-Pro cannot communicate with the switch using SNMP, the status bar shown when you go to the Network, sub-tabs and select a switch, will include No SNMP. In this case, sFlowTrend-Pro will be unable to display friendly names for the switch and its interfaces. It will also be unable to use SNMP to configure the switch to send sFlow. Verify that the that the sFlowTrend-Pro is using the correct SNMP settings and that there are no firewalls in the network or on the host that are blocking SNMP.

More diagnostics are available by using the Configure agents menu item and viewing the status details for the switch either by moving the mouse over the status color indicator to activate the tooltip or by clicking on the edit button. For example:

  • Timed out indicates that the SNMP v2 community is incorrect or there are firewalls in the network or on the host blocking SNMP.
  • Cannot decode response, Decryption failed, and User has no access privileges, indicate that the SNMP v3 settings being used by sFlowTrend-Pro do not match those configured on the switch. Check that the authentication and privacy passwords are correct, that the correct authentication protocol is being used and that the user has appropriate access privileges.

The sFlowTrend-Pro log file in the sFlowTrend-Pro server home directory (see Section 13.2.1, “General system configuration”) may give additional details.