S-PE Node Inserting Control Word for ECMP Packet Order

The patent introduces an intermediate S-PE device that acts as a mediator between the conventional PE and the network. This S-PE device automatically detects whether incoming packets contain a CW, inserts or removes it as needed, and forwards the packets. This intermediary solution allows conventional PEs to continue operating without modification while ensuring packets receive proper CW treatment in the network, thus resolving the contradiction between compatibility and reliability.

Instead of requiring all PE devices to have CW insertion capability, the patent applies local quality by enabling only the specific S-PE devices in the network core to possess this capability. The conventional PEs at the network edge can remain simple and cost-effective, while the S-PE devices in the middle perform the sophisticated CW insertion/removal operations. This localized approach to capability distribution achieves reliable ECMP behavior without requiring expensive upgrades across the entire network.

The S-PE device implements self-service by automatically detecting whether incoming packets require CW insertion based on simple criteria (whether the packet already contains a CW). The device autonomously decides when to insert, remove, or leave the CW unchanged, and performs the appropriate operation without external control. This self-service approach minimizes the control logic complexity while achieving reliable packet protection through automatic CW management.