There is MPLS VPN traffic traversing through a TE intermediate router. What is the MPLS packet label stack sequence (from outer to inner) for the VPN traffic on this router?
A.
TE label, IGP label, VPN label
B.
IGP label, TE label, VPN label
C.
TE label, VPN label, IGP label
D.
VPN label, IGP label, TE label
E.
IGP label, VPN label, TE label
Answer is A.
We can follow the Layers flow in OSI. Layer 1 is outer most and Layer 7 is inner most. That’s, TE on 2.5 layer is outer most and IGP on layer 3 and VPN on layer 4