Segmentation is another use case that drives these changes in the WAN. Oftentimes, businesses have different departments that require separation. For example, Research and Development may need to be segmented from the Production environment. There may be extranets that connect to partners, or the business may be merging or acquiring another business in which the networks need to be able to communicate but segmentation may still be required between the two. This may require multiple topologies that can be managed as one. Figure 1-10 depicts an end-to-end segmentation topology, along with how different VPNs are carried over the tunnels. Each of these tunnels terminates at an edge router within the environment.
FIGURE 1.10 End-to-End Segmentation