Application of SR-MPLS TE in DCN Traffic Optimization
A node on a conventional IP network selects the shortest path as an optimal route, regardless of other factors such as bandwidth. This routing mechanism may cause congestion on the shortest path and waste resources on other available paths. As shown in Figure 5-30, the traffic destined for Site2 is transmitted on the shortest path (PE1 -> P1 -> PE2). When the packet traffic exceeds the path bandwidth, traffic loss occurs. The SR-MPLS TE function can be configured on the network to allocate some traffic to idle links (PE1 -> P2 -> P3 -> PE2) so that traffic is distributed on the network more properly.
Similar to common TE tunnel techniques, SR-MPLS TE provides various reliability techniques. CR-LSP backup provides E2E protection for MPLS TE tunnels. If the ingress node detects a primary CR-LSP failure, it switches traffic to a backup CR-LSP. Once the primary CR-LSP recovers, traffic is switched back from the backup path. This implements backup protection for the primary CR-LSP. If both the primary and backup CR-LSPs fail, SR-MPLS TE can also trigger a best-effort path to ensure network reliability.