The device triangulation method necessarily finds the best zone in terms of performance – but an application with compliance requirements to communicate only with servers in a certain country or state might be better served using another method.

AWS Cloud Map

Another approach is to maintain a central directory of carrier IPs that mobile applications can use to look up the closest carrier IP given their current GPS coordinates. This can be done using AWS Cloud Map. This is a managed cloud resource discovery service that is integrated with other AWS services:

Figure 7.13 – Using AWS Cloud Map to discover carrier IPs based on GPS coordinates

AWS Cloud Map allows you to create namespaces that dynamically track the state and location of constructs such as EC2 instances or containers in ECS/EKS. Because it is possible to attach arbitrary attributes to such things via tags, GPS coordinates for a given carrier IP can be retrieved by the mobile device. At that point, it would be up to the application on the device to calculate the closest carrier IP given the device’s location. In addition, the application needs permission to retrieve its location from the device – something that not all users are comfortable with.

Carrier-developed EDS

Another method is to leverage the fact that the MNO knows the physical location of all devices on its 5G fabric. Carriers such as Verizon have developed their own service discovery APIs that they make available on their 5G fabric. Mobile devices can query Verizon’s EDS service, which already knows both the physical location of the mobile device’s UE Identity and all carrier IPs it is servicing:

Figure 7.14 – Dynamic edge discovery with Verizon EDS

This approach simplifies the implementation on the mobile application by removing the requirement for permission to query the device’s GPS. It also eliminates the need to calculate coordinates and figure out which carrier IP is best. However, this comes at the cost of increased management overhead associated with keeping your application’s services registered in service profiles in Verizon’s EDS.

Security considerations

Carrier-developed EDS systems require client devices to be in possession of API keys that grant access to determine the location based on the client IP address/UE Identity. Depending upon the application’s architecture, granting these keys to thousands of devices could represent a vulnerability. Some customers, therefore, implement a caching tier on a central AWS resource (such as a container in the parent region). Only this central caching tier interacts with the EDS system, providing an opportunity for the application owner to directly inspect calls and respond to anomalous behavior.