Testing Video over Carrier LDP/RSVP-TE MPLS

By Chris Chapman On February 9, 2010
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One of the great features of Spirent TestCenter is its ability to directly test services over structured Ethernet. This is critical to carriers because their business model is becoming increasingly dependent upon revenue from IP video.

With Spirent TestCenter, you have the ability to completely isolate the carrier Ethernet DUT, regardless of its role. Say the device under test is an MPLS P router. With Spirent TestCenter topology emulation technology, you can model routers behind routers as true objects.

Once you build out the IGP, you can model MPLS, adding depth and width to the MPLS tunnels. Then, within the LSPs, you can source Unicast and multicast MPEG2-TS video streams over unicast, or optionally over multicast, with Spirent TestCenter stateful PIM-SM and SSM support.

How is this unique to the industry? Because of the pure object-oriented network-module features of Spirent TestCenter, structures are layered upon each other as opposed to a relational model, where entities are next to each other in tables. When you test a lower-layer feature, such as a BGP route flap event, the event instantaneously traverses up and down the relationship tree to highlight the impact.

With relational models, you would have to reconfigure the IGP and then manually propagate the changes to each table in the tester. Many events align within microseconds and thus become untestable in relational models. In the case of video, the BGP convergence loss may or may not affect user experience.

Say a flap event loses 10 datagrams. Depending upon the encoding of the video (SD or HD, MPEG2-TS with more or fewer I-Frames) the event may or may not affect the MPEG GPOB. If I-Frames are lost within the data stream, you will see MPEG artifacts on screen (blockiness, blur, etc). If P-Frames are lost, this is fairly recoverable and you may not see any effect.

The point is that unless the test tool has the ability to relate objects with real-time processing, you will not be able to test many real-world errors with video. Properly testing IPTV is critical to the success of the business.


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