We have already discussed IPsec in the previous section. Here, we will discuss how IPsec complements WAN technology. Layer-3 encryption is well-suited to environments where you have low-bandwidth connections and do not have the devices to support encryption at Layer-2 or Layer-1 levels. Organizations are running WAN technology in a different way, for example, with ATMs, Frame-Relay, Metro-Ethernet and MPLS-based solutions. The ultimate security question is: Who do you trust with your business-critical data? If your answer is the service provider, then you probably do not need to encrypt your data. However, if your answer is nobody, then you must transmit data to an encrypted service provider.
Let's look at the MPLS ...
