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Is Your SDN Solution Ready for Rate-Limiting and QOS Traffic Engineering Functionality?

April 17, 2014 by Ixia Blog Team

As software defined networking gradually makes its way into data center networks, the end users’ expectation are that it must meet or exceed the benefits offered by traditional networks. So, how can OpenFlow be used to perform rate limiting and QoS traffic engineering?

The OpenFlow v1.3 standard has added Meter/Band functions to support various simple QoS operations such as rate-limiting, QoS remarking, or packet drop. A meter measures the rate of packets assigned to it, and enables controlling the rate of those packets. When installing flows, a controller can attach meters directly to each flow entry as opposed to queues that are associated to ports.

A meter entry contains the following fields:

  • Meter Identifier - A 32 bit unsigned integer uniquely identifying the meter
  • Meter Band - Each meter has one band. The band specifies the rate at which the band applies and the way packets should be processed. If the current rate of packets exceeds the rate of the band, the packets are processed in the way specified by the band

A meter band contains the following fields:

  • Band Type - Defines how packets are processed. Packets that exceed the band rate are dropped or remarked
  • Rate - Defines the lowest rate at which the band can apply

How Ixia can help to test rate-limiting and QoS with SDN?

Ixia’s OpenFlow solution is widely used by many industry leading customers. With the IxNetwork 7.30EA release, we added several key advanced OpenFlow features including Meter/Band support.

Using OpenFlow controller emulation, a user can push millions of flows with various Match/Actions, can associate Meter/Band with each flow entrie,s and ensure that the OF switch can successfully install all flows correctly with right QoS policy applied by Meter. Then it generates data plane traffic based on each matching endpoint to ensure the switch is strictly forwarding traffic based on configured meter rate.

The expectation is that when the Meter/Band type is configured as Drop, the OF switch should start dropping the packets if it exceeds the configured rate. If the Meter/Band type is configured as DSCP Remark, the switch should start remarking packets that are exceeding specified rate.

Here’s the snippet from IxNetwork GUI showing meter/band features:

sdn20qos

sdn20qos202

  • Supports multiple meter bands per Meter_ID
  • Rate (kb/sec), Rate (packets/sec), Burst Size, and Collect statistics flag support
  • Drop, DSCP Remark, and Experimenter Band Type
  • Allows user to dynamically Add/Modify or Delete Meter

This was one of the key test cases at EANTC’s hot staging event held at their lab in Berlin in February, 2014, and this solution was publicly showcased live at the MPLS/SDN World Congress event in Paris, March 2014.

For more information about this event, please take a look at following white paper published by EANTC:

http://www.eantc.de/fileadmin/eantc/downloads/events/2011-2015/MPLSEWC2014/EANTC-MPLSSDN2014-WhitePaper-online.pdf

As always, feel free to drop in your comment, questions or feedback!

Additional Resources:

Ixia SDN solution

EANTC White Paper

IxNetwork