In frame-relay MPLS, where is the label imposed?
A.
Between Layer 1 and Layer 2 headers.
B.
Between Layer 2 and Layer 3 headers.
C.
In the VPI/VCU fields.
D.
In the VPI field alone.
Explanation:
MPLS labels are assigned to packets based on groupings or forwarding equivalency classes
(FECs) at the ingress eLSR. A FEC is a group of packets from a source IP address that are all
going to the same destination.
The MPLS label is imposed between Layer 2 and Layer 3 headers in a frame-based packet
environment, or in the Layer 2 virtual path identifier/virtual channel identifier (VPI/VCI) field in cellbased networks like ATM.