OLT Pipeline does not provide inner tag of Q-in-Q flows correctly

When a Q-in-Q downstream flow is encoded in the OltPipeline of ONOS, it places the UNI egress port number as the metadata in the flow rule for table 0, but not the inner tag.  This is done so that the flow-decomposer can lookup the route and compute the proper in-port/out-port on the OLT decomposed flow.

However, the inner-tag to match on is never encoded in the decomposed flow that the OLT receives.  Prior to this, most people would use a UNI logical port number that matched the inner-tag or would use fields in the xPON vENET entry to encode this information.

With the deprecation of xPON, this issue makes it very difficult to properly determine the proper C-Tag to match on in the downstream direction.

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A possible solution for this is to use the metadata field (64-bits) that current encodes the output port (32-bits) to also include the inner-tag (12-bits).   The inner-tag can be placed in the upper 32-bits by the OltPipeline in ONOS.

In the flow decomposer, these fields can be easily retrieved.  Also, since the inner-tag should never be zero, the flow-decomposer can detect if it is talking to a new (fixed) OltPipeline driver or an old one and act appropriately.

This is closely related to VOL-460 that was never addressed in 2017.

OltPipeline.diff.txtOltPipeline.diff.txt

flow_decomposer.diff.txt

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Attached to this issue are two diffs of code (needs cleaning up) that can be the basis for a fix