Introducing FRR
FRR is a mechanism used in IP/MPLS networks to minimize the impact of network failures on the traffic flow. When a fault occurs in the network, the response varies depending on the protocol in use. Generally, there are two primary approaches to address the issue:
- Wait for convergence: In both traditional MPLS protocols, LDP and RSVP-TE, the network initiates a reconvergence process to identify the optimal new path from the source to the destination. The MPLS label distribution protocols rely on this reconvergence to re-establish the end-to-end MPLS path over the newly identified route. This period is known as convergence delay, during which traffic may be dropped, leading to the undesirable phenomenon of traffic black holes.
- Local fast rerouting at the Point of Local Repair (PLR): While the network is reconverging, the router that detects the fault can reroute traffic around the failure, ensuring continuity of service. This diversion typically occurs within...
