Direct Internet Access
One of the most common use cases is something called Direct Internet Access (DIA). DIA gives branches the capability to send traffic directly out of the local Internet transport instead of carrying it all the way back to a centralized data center to be inspected. This allows for cloud-based applications to go directly to the Internet and cloud service providers without having to use unnecessary WAN bandwidth. This is increasingly becoming the method that is being adopted. Figure 1-11 depicts the traditional way that cloud applications are accessed. This causes suboptimal performance for users trying to access these applications. This also, as mentioned earlier, puts a strain on the WAN infrastructure, as the expensive and limited WAN bandwidth is being consumed by applications that could be sent directly to the Internet from the remote site. This also introduces increased application latency, as the traffic has to cross the entire network to get to the data center to reach the Internet.
FIGURE 1.11 Traditional Cloud Application Access via WAN
Looking at changing and rethinking the WAN allows for different mechanisms that will allow for better performance and scale. A great example of this is using the Direct Internet Access design to offload the latency-sensitive cloud applications directly to the Internet. This method also gives the flexibility to have a local firewall or inspection device in the branch to ensure the branch is protected from any malicious threats coming into the local branch Internet link.
Figure 1-12 shows an example of what this would look like in a new WAN environment.
FIGURE 1.12 Direct Internet Access and Cloud Access Topologies