Virtual Network Monitoring (sFlow + Mininet)

[Abhishek Dwaraki]

Hi,

    I am new to sFlow and was investigating if I could use it for some SDN work that I am doing. I will try and detail my setup and requirements as much as possible. Any advice is much appreciated. Currently, I do not have access to hardware and hence much of my setup is built on Mininet and ONOS as a controller. I do not even have multiple machines to manage a multi-machine OVS setup.

1. I was to do some network monitoring for the purpose of NFV service chaining. My requirements are that I be able to weight the network topology graph in some way, which means collecting a workable metric live of some sort. Delay or link latency is what I need for now, but link utilization can also be considered if available.

2. I see that sFlow has the capability to retrieve CPU load/utilization metrics. Does this work in an environment like Mininet? I know that Mininet runs on a single instance of OVS and am not quite sure if sFlow can capture individual switch loads? If it can, could someone please point me to some documentation that I can use? 

3. With regards to #2, if sFlow can capture CPU utilization, is it restricted to network devices or can it query loads for hosts in Mininet too? If it is possible, any links to documentation please?

Hope I can find some answers here. Thanks in advance.

Regards,

Abhishek.

[Peter Phaal]

sFlow's packet sampling mechanism gives you a real-time view of link utilization. Measuring delay / queueing with sFlow requires instrumentation in the datapath, something that is starting to appear in physical switches, e.g.

http://blog.sflow.com/2015/12/broadcom-broadview-instrumentation.html

However, while delay information is extremely useful, utilization is a better control metric for SDN/NFV:

http://blog.sflow.com/2013/02/delay-vs-utilization-for-adaptive.html

http://sflow.org/sFlowQoS/

In a Mininet setup, there is one instance of Open vSwitch no matter how many logical switches are being emulated. You need to map the Open vSwitch ports to the logical ports in your Mininet setup. If you look at the leafspine.py script in the following example, you can see how this is accomplished:

http://blog.sflow.com/2014/04/mininet-integrated-hybrid-openflow.html

The above example uses the sFlow-RT real-time analytics software. sFlow-RT is being used in a number of SDN/NFV projects and you might want to consider using it in your project:

http://sflow-rt.com/index.php

If you have questions about the example, or would like to connect to other researchers, you should ask them on the sFlow-RT group:

http://sflow-rt.com/community.php

It is possible that the Host sFlow agent might be able to give you cpu/memory/IO stats for the Mininet containers used to emulate switches and hosts:

http://www.sflow.net/

You will probably need to make some modifications to the code since only Docker APIs are currently supported. If you have any questions about Host sFlow, you should ask them on the Host sFlow mailing list:

https://lists.sourceforge.net/lists/listinfo/host-sflow-discuss

[Abhishek Dwaraki]

Many thanks Peter. The help is much appreciated. I will look into the appropriate modules and get back if I have any other questions. Thanks once again.

Abhishek.

[Abhishek Dwaraki]

Hi Peter,

              I was trying to execute the leafandspine example in the hybrid networking link that you provided. The ecmp.js file imports a json2.js file from extras. I do not find this file in the downloaded tar for sflow-rt. Any pointers about where this file can be found?

Regards,

Abhishek.

On Saturday, February 13, 2016 at 10:37:41 AM UTC-5, Abhishek Dwaraki wrote:

[Peter Phaal]

You can remove the include line, you don't need the file. JSON
encoding / decoding is built in.

Could you please direct future questions about sFlow-RT to the
sFlow-RT mailing list, http://sflow-rt.com/community.php

Peter

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