Thursday, 27 April 2017

Running sFlowTrend in a Docker container

sFlowTrend is now available as a Docker image. Docker makes it really easy to try out sFlowTrend, and you can also use it as a convenient way to run it in production. It will work for both the free sFlowTrend, or for sFlowTrend-Pro - just select the free option, or enter your license number in the System Configuration>License dialog.

To run sFlowTrend in Docker, use the command

docker run -v /var/local/sflowtrend-pro:/var/local/sflowtrend-pro -p 6343:6343/udp -p 8087:8087 -p 8443:8443 -h sflowtrend-pro -e TZ=Europe/London -d --restart unless-stopped sflow/sflowtrend

This will run the latest version of sFlowTrend. You can select a specific version using the appropriate tag, e.g. sflow/sflowtrend:6.5.04. See the docker hub repository at for more information on the versions available. Some explanation of the command line options used is worthwhile:
  • -v /var/local/sflowtrend-pro:/var/local/sflowtrend-pro mounts the specified directory on the host at /var/local/sflowtrend-pro in the container. This means that the data and configuration will be persistent, and available in this location. Instead of this, you could optionally use a Docker volume, in which case the persistent data would be in the volume. If you don't specify the volume, the data will be lost from one container to the next - this might be OK for evaluation purposes.
  • -p 6343:6343/udp -p 8087:8087 -p 8443:8443 publishes the required network ports. You can map the ports used in the container to something different on the host if you like. UDP port 6343 is the sFlow port, and if you use something else then your network infrastructure would need to be configured to send sFlow on the new port. Port 8087 is used for the http connection for the sFlowTrend web client, and port 8443 for the https connection; if you change these, then the new port would need to specified in the web browser you are using to connect to sFlowTrend.
  • -h sflowtrend-pro sets the hostname of the container. This is important if you are using sFlowTrend-Pro: you would need to use the hostname that matches your license. The hostname is also shown on the dashboard.
  • -e TZ=Europe/London sets the timezone of the container. All data in sFlowTrend is shown in this timezone, so it is important that you set it correctly for your location. You can use a standard Linux timezone identifier here.
  • -d runs the container in the background.
  • --restart unless-stopped automatically starts the container when the Docker engine starts.
When you first run sFlowTrend in Docker, the latest version will be pulled from the Docker hub. After this, because it is cached locally, on future runs it will run the same version. If a new version of sFlowTrend has been released, you can force this to be downloaded using the command
docker pull sflow/sflowtrend

Configuring sFlow using SNMP in a container

sFlowTrend has the ability to configure sFlow on some switches using SNMP. This works with only a few vendors devices, but can be easier than using the CLI on the switch to set up sFlow. If you are using SNMP to configure sFlow with sFlowTrend in a Docker container, then you have to ensure that sFlowTrend knows the correct address to use for sFlow data. This is because, using the default Docker network (bridge), the container is effectively run behind a logical NAT device. The easiest way to set this up is to first run the container as above, and then stop it after 10 seconds or so; this will create the file structure and empty configuration file in /var/local/sflowtrend-pro. Then follow the instructions for the configuration option sflowtrend.natReceiverAddress at

When you run the container a second time, the address you entered will be available in the System Configuration option for the sFlow receiver address. Select this, and the sFlow data should be directed to that address.

Monday, 27 February 2017

Using sFlowTrend to analyse IEEE 802.1ah (PBB or MAC-in-MAC) traffic

The Provider Backbone Bridges (PBB or MAC-in-MAC) standard IEEE 802.1ah defines an architecture and protocol that allows service providers to build large, scalable ethernet bridged networks, interconnecting multiple Provider Bridge networks without losing each customer's individually defined VLANs. It operates using a MAC tunnelling scheme in which a customer packet, including MAC addresses, is encapsulated in a new ethernet frame with new MAC addresses (the backbone bridge MAC addresses). This eliminates the need for backbone core bridges to learn all MAC addresses of every customer and provides complete separation of provider and customer domains. However, visibility of both the backbone traffic and the encapsulated customer traffic is important for troubleshooting configuration problems and managing performance. sFlowTrend (version 6.5 onwards) understands the IEEE 802.1ah frame format, decoding the outer backbone header and the inner customer frame. Here is an example of using sFlowTrend-Pro to gain full visibility of traffic in a PBBN.

The diagram below illustrates a typical IEEE 802.1ah PBB frame and shows the key fields used by sFlowTrend-Pro to represent the header fields. The sFlowTrend-Pro help gives a full list of the MAC, VLAN, priority, and IEEE 802.1ah key fields.

One way to view the details of traffic in a PBBN, is to use the Network > Top N tab and create a custom top N chart.

In this example we have build a custom top N chart showing the backbone header fields and the MAC and IP addresses and VLAN in the customer frame. Selecting this custom top N chart from the Chart selection list, generates a chart showing the details of the PBB traffic.

Using sFlowTrend to analyse tunnelled and encapsulated traffic

Layer 3/4 tunnels (Geneve, GRE, NVGRE, VXLAN) are often used to virtualise network services so that communication between virtual machines can be provisioned and controlled without dependencies on the underlying network. Hiding the physical network topology is a useful abstraction which offers a significant benefit of operational flexibility, however lack of visibility into the physical and virtual network can result in poorly placed workloads, inefficient use of resources and as a consequence, performance problems. sFlowTrend-Pro v6.5 provides the comprehensive visibility into tunnelled traffic which is essential for effective management of these more complex environments. Here is an example of how you can use sFlowTrend-Pro to understand and analyse tunnelled traffic.

sFlowTrend-Pro recognises VXLAN tunnelled traffic using the well known port UDP 4789. It then decodes the encapsulated packet in the UDP payload and stores the encapsulated packet header fields using key fields such as sourceAddress.1, destinationAddress.1 etc. It also records the VXLAN Network Identifier (VNI). The sFlowTrend-Pro help includes a section on L3/4 encapsulations which lists the key fields available for tunnelled traffic. One way to view a VXLAN tunnel is to Network > Top N tab and select the Top source-destination flows chart and then add a filter isVXLAN:

If you click on the source and destination address in the legend, you can also add the tunnel end points to the filter:

To see the traffic inside the tunnel, you can build a custom top N chart (click on the edit button next to the Chart selection list):

In this example we have built a custom Top N chart with fields vni, sourceAddress.1, sourcePort.1, destinationAddress.1, destinationPort.1. Selecting this custom top  N chart from the Chart selection list, generates a chart showing the details of the traffic flows carried by the tunnel that we are filtering on:
You can use a similar technique to look at traffic flows carried by other tunnelling protocols (Geneve, GRE, NVGRE).

You can also create reports using the Reports tab and creating a query section using Advanced settings to select key fields for encapsulated packets.

Tuesday, 10 January 2017

Upgrading sFlowTrend

sFlowTrend will tell you when a new version is available, if it has internet access. You can also check using Configuration>Check for updates in the web client.

To upgrade sFlowTrend, you just need to install the new software on top of the old. There's no need to uninstall first, that is all taken care of by the installer. The one thing that is important to remember is to use the same version of installer as you did for the initial install:
  • If you used the 32-bit Windows installer, update using the 32-bit installer. Just run the new installer, and it will uninstall the old version and install the new one.
  • If you used the 64-bit Windows installer, update using the 64-bit installer. Again, just run the new installer.
  • If you used the interactive Linux installer, use this to upgrade, again by running the new installer.
  • If you used a Linux rpm package to install, then upgrade using the command
  • # rpm -Uvh sFlowTrend-linux-version.rpm
  • If you used a Linux deb package to install, then upgrade using the command
  • # dpkg -i sFlowTrend-linux-version.deb
If you want to change how sFlowTrend is installed (eg, from the Linux interactive installer to a package), then you must first uninstall sFlowTrend using the original method. This will not remove any configuration or data. Then install using the new method. If sFlowTrend was originally installed using the interactive installer, you can use the uninstall program located in the main installation directory to uninstall it.

The data and configuration should not be affected when upgrading, but you can of course back this up to be sure. The best way is to stop the sFlowTrend-Pro service, then just copy all of the contents of the sFlowTrend-Pro data directory (this is called the home directory in the user interface, you can see it using options dialog in the Java client or the system config dialog in the web client). Once you have copied it (or zipped or tared it up as appropriate), then restart the service.