Converged network design
Figure 86: Sample spanning tree
If the primary router fails, the secondary router becomes both the active router and the root bridge, and traffic from the switches flows on the reconfigured spanning tree along links C & D. If bridge priorities are not managed, traffic from one switch may be directed through the secondary router and the other switch as normal operation.
Figure 87: Alternate configuration - Layer 2
In the alternate integrated device configuration, bridge priority is less significant but other factors may add to complexity. In particular, link sizing becomes an issue if there are not enough Gigabit Ethernet aggregation ports. If a link aggregation group (LAG) is used, flow distributions must be understood to ensure correct behavior.