MPLS Fundamentals

FRR

TE is usually enabled in the core network, where the capacity of the links is high. If a link or a router fails, traffic is rerouted around the failure. This rerouting happens for IP and for MPLS traffic relatively fast. However, even if the rerouting takes only a few seconds, it might mean that a lot of traffic is dropped to the point of failure because of the high capacity of the links. For certain traffic, such as Voice over IP (VoIP), this can be devastating for the service. Although links can potentially be protected at Layer 1—for example, with a mechanism called automatic protection switching (APS)—having a protection at the level of MPLS is best. APS is a well-known mechanism for protecting optical links. A disadvantage of APS is ...