Tuesday, June 16, 2009

Trying out sFlow

If you are interested in network-wide visibility and want to start experimenting with sFlow, take a look at your network and see if any of the switches are sFlow capable. Most switch vendors support sFlow, including: Brocade, Hewlett-Packard, Juniper Networks, Extreme Networks, Force10 Networks, 3Com, D-Link, Alcatel-Lucent, H3C, Hitachi, NEC AlaxalA, Allied Telesis and Comtec (for a complete list of switches, see sFlow.org).

If you don't already have switches with sFlow support, consider purchasing a switch to experiment with. There are a number of inexpensive switches with sFlow support (check the list of switches on sFlow.org), alternatively you may be able to pick up a used switch on eBay.

Finally, the open source Host sFlow agent can be used to host traffic and traffic between virtual machines on a virtual server (Xen®, VMware®, KVM).

Once you have access to a source of sFlow data, you will need an sFlow analyzer. The sFlowTrend application (shown above) is a free, purpose built, sFlow analyzer that will allow you to try out the full range of sFlow functionality, including:
  • decoding and filtering on data from packet headers (including VLANs, priorities, MAC addresses, Ethernet types, as well as TCP/IP fields)
  • accurate analysis, trending and reporting of packet samples
  • trending of sFlow counters
  • support for sFlow MIB to automatically configure sFlow on switches
Many traffic analyzers claim support for sFlow, but provide only partial support. It is worth starting with sFlowTrend to see the full capabilities of sFlow and to gain experience with sFlow monitoring before evaluating larger scale solutions.

Future posts on this blog will use sFlowTrend to demonstrate how sFlow monitoring can be used to solve common network problems. Downloading a copy of sFlowTrend will allow you to try the different strategies on your own network.

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