When everything is configured correctly, Java Web Start should automatically install sFlowTrend-Pro. However, sometimes the browser is not aware of Java Web Start. In this case, you have to tell it manually to run the Java Web Start program. This is called javaws. You may need to browse to the location of javaws - on Microsoft Windows, it should be installed in C:\Program Files\Java\jre1.5.0_06\bin (note the path may vary depending on the specific version of Java installed).

When Java Web Start is installed correctly, it should automatically be launched from the browser. If the browser displays a text (xml) file instead, then right-click on the link, select save link as or save target as, and save the file as sFlowTrend.jnlp.

Then, try double-clicking on the saved file. If this still doesn't work, then open a command prompt window, and run javaws sFlowTrend.jnlp (you will need to make sure that sFlowTrend.jnlp is in the current directory).

sFlowTrend-Pro is written in Java, and needs a minimum of Java v5.0. The sFlowTrend-Pro installation page will normally try to install Java for you, if it is not already installed. However, in some circumstances this is not possible, and in this case the JRE should be installed manually. Also, in the case of other installation problems, it is often easiest just to re-install the Java JRE.

The JRE is available from Sun's java.com web site

sFlowTrend-Pro has an 'LED' at the bottom right of the window. This flashes green for every sFlow sample received. If it is not flashing, then no samples are being received. This can happen because no switch is configured to send sFlow, because there is insufficient network traffic on the switch to generate any sFlow, or because a firewall is blocking the sFlow data.

First, make sure that a switch is configured to send sFlow to sFlowTrend-Pro. With some switches, this can be done automatically, using sFlowTrend-Pro. Use the menu option Tools → Configure switches , and then Add. For other switches, sFlow must be configured through the switch's command line interface - refer to the manual for the switch.

If you think that sFlow is configured correctly, then try to ensure that sufficient network traffic is flowing through the switch. See Section 7.1.5, “sFlowTrend-Pro is not receiving sFlow from switch”

sFlow works by sending network packets to an sFlow collector, in this case sFlowTrend-Pro. The network packets are sent using UDP, on port 6343. If a firewall, either on the system running sFlowTrend-Pro or in the network, is blocking port 6343, then no sFlow data will reach sFlowTrend-Pro. Make sure that both the firewall on the system and all network firewall are allowing sFlow data through.

This error message almost always means that another application is already using the default sFlow port, which is UDP 6343. A port can be used by only one application. If you try to run sFlowTrend-Pro more than once on the same system or another sFlow collector is already running on the same system, then you will see this error. Examples of other sFlow collectors are InMon Traffic Sentinel, a switch vendor's element manager, or one of the other sFlow applications available.

To find out which application is already using the sFlow port, follow these instructions:

Once you have identified which application is using the sFlow port, you can decide which application to run at any one time, or you can change the port that sFlowTrend-Pro uses, by entering a new port number in the dialog.

Note

If you change the port that sFlowTrend-Pro uses and your switches are configured using SNMP to send sFlow; (see Section A.1.1, “Using SNMP to configure the switch to send sFlow”), sFlowTrend-Pro will automatically reconfigure your switches to send sFlow to the new port. However, if your switches are configured via the CLI to send sFlow and you change the port used by sFlowTrend-Pro, you must also manually reconfigure your switches to send sFlow to the new port (see Section A.1.2, “Using the switch CLI to configure sFlow”).

Occasionally, a host firewall can also cause this error message. If you could not find another program using the sFlow port, then refer to the section above, on firewalls Section 7.2, “Frequently asked questions”.

The grey part of a bar in a Top N traffic chart indicates that the traffic was from contributors not in the top N for the currently selected interval. See Section 3.2.2.1, “Understanding the Top N traffic chart”.