Comment 4 for bug 1509939

Reviewed: https://review.opencontrail.org/15727
Committed: http://github.org/Juniper/contrail-vrouter/commit/bcbbf1c6fd0ca85b6fc21fc96795997d9b79bbf9
Submitter: Zuul
Branch: master

commit bcbbf1c6fd0ca85b6fc21fc96795997d9b79bbf9
Author: Anand H. Krishnan <email address hidden>
Date: Mon Oct 26 11:25:12 2015 +0530

Logic to identify the nature of label in fmd

Post L2 flow support, vRouter started using the label in the forwarding
metadata to also store VXLAN identifier. For MPLS-O-X(GRE/UDP) packets,
the label indicates the MPLS label of the packet. For VXLAN tunneled
packets, the label indicates the VNID.

The logic that identifies this information has turned out to be buggy,
resulting in VNID being identified as a MPLS label and thus sending the
packet to a wrong interface/VM. Till now, we used to mark the label as
VNID only if the packet had hit VRF translation nexthop (the vxlan kind)
AND if the packet was cached in the flow entry because of that
particular nexthop, which never happens and hence the label was always
identified as a MPLS label.

We now mark a flag indicating the type of the label, whenever the type
is identified. To be more explicit, the label is now set in the fmd with
an API that takes the type of the label, so that mistakes can be avoided.

Closes BUG: 1509939

Change-Id: I63167986b4532d6820b0c76f267c61ca788e8fd4