Route redistribution, which was described in detail in the previous chapter, is another tool that can be used for path control. Path control can be implemented by redistributing the same or different routes with higher metrics at the ASBR, effectively ensuring that internal routers will prefer the path with the lowest metric to reach the external destination network.
When using different metrics during route redistribution, if only one protocol is configured to use different metrics, this will typically result in asymmetric routing as shown in Figure 4-3: