T-MPLS network scenarios

T-MPLS label processing

The NE performs the following operations on the label:

Push: T-MPLS supports the capability to push two labels (the pseudowire (PW) and PSN Tunnel labels) to a service packet entering the T-MPLS domain (ingress UNI), where both PW and PSN Tunnels are generated.
Pop: T-MPLS supports the capability to pop two labels (the psuedowire (PW) and PSN Tunnel labels) from a T-MPLS packet exiting the T-MPLS domain (egress UNI), where the PW-LSP and PSN Tunnel are terminated.
Swap: T-MPLS supports the capability to swap the T-MPLS label at the Tunnel layer between T-MPLS NNI interfaces at a provider node (LSR).

Notes to Figure 3-8, Label processing: push, swap, pop:

The change of the LSP label number in adjacent hops (Tunnel1, Tunnel2) means that they are different LSPs (different Tunnels)
The change of the LSP label color in adjacent hops, with the same label number, means that it is the same LSP with swapped label value.

Figure 3-8: Label processing: push, swap, pop

Scaling Ethernet services with T-MPLS

Figure 3-9: Scaling Ethernet services with T-MPLS

T-MPLS single domain scenario

Figure 3-10: T-MPLS single domain scenario

T-MPLS dual homed scenario

Dual homing is used in a ring area where the Tunnel spokes are connected to the intermediate hub nodes in a dual homing, implemented using 1:1 Tunnel Redundancy without APS. TMPLS encapsulated R-APS messages are used as a MAC flushing mechanism for the dual homed nodes.