Some ATM switches in the network might not run MPLS. The solution to this problem is to run Virtual Path (VP) tunnels across the non-MPLS-aware ATM switches. Figure 5-13 shows a network with ATM switches that are not MPLS-aware. A VP tunnel is created across those ATM switches to carry the LVCs, which are created as needed on the VP tunnel. The VCIs are mapped to the MPLS labels and carry the “labeled” ATM cells.
In the example network, the ATM LSR denver-atm is now non-MPLS-aware. Figure 5-14 shows the VP tunnel across the LSR denver-atm.