Networks configured with redundant paths do not inherently guarantee optimal performance when failures occur. The use of multiple routing protocols or redundant links can lead to sub-optimal routing and odd convergence scenarios.
Policy-based routing, or PBR, provides a capability to decide what traffic flows are sent across specific links regardless of the underlying routing protocol metric, using classification based upon source or destination IP address, L4 port, or other information contained in the L4 header.
Stuck-in-Active: Journal of an IT-Network Administrator 