AWS Cloud WAN Insertion via NFG

This scenario is achievable with AWS Cloud WAN's service insertion feature using Network Function Groups (NFGs). You can set up your inspection in eu-west-1 and configure the service insertion policy to route all cross-segment traffic through this region for inspection before reaching its destination, regardless of the source or destination region.

To implement this, you would create an NFG in eu-west-1 that includes your inspection VPC or security appliances. Then, in your Cloud WAN policy, you would use the "send-via" segment action with the "single-hop" mode. This configuration allows you to specify eu-west-1 as the preferred region for inspection.

Your policy might look something like this:

"segment-actions": [
  {
    "action": "send-via",
    "segment": "*",
    "mode": "single-hop",
    "when-sent-to": {
      "segments": "*"
    },
    "via": {
      "network-function-groups": ["InspectionNFG"]
    }
  }
]

In this configuration, you would also set an ordered list of regions with eu-west-1 as the preferred region for inspection.

Regarding potential issues:

1. Session timeouts: While this setup doesn't inherently cause session timeouts, you should be aware that routing traffic to eu-west-1 for inspection before reaching its destination in other regions (like us-east-1 or ap-south-1) will introduce some latency. This additional latency could potentially lead to timeouts if your applications have very strict timeout settings.

2. Asynchronous routing: AWS Cloud WAN is designed to handle complex routing scenarios, so asynchronous routing shouldn't be a significant concern. The service manages route propagation automatically based on your policy.

However, it's important to note that this centralized inspection model might introduce increased latency for traffic between us-east-1 and ap-south-1, as it would need to travel to eu-west-1 for inspection before reaching its destination. This could impact application performance, especially for latency-sensitive applications.

To optimize this setup, you might consider:

1. Ensuring your inspection appliances in eu-west-1 are properly sized to handle the global traffic load.
2. Monitoring network performance and adjusting your configuration if needed.
3. For latency-sensitive applications, you might explore using Cloud WAN's capability to set up multiple NFGs in different regions and use policy-based routing to balance between centralized and distributed inspection models.

While this setup is achievable and can simplify your global security inspection, it's crucial to carefully consider the trade-offs between centralized security control and potential performance impacts, especially for geographically distant regions.
Sources
Simplify global security inspection with AWS Cloud WAN Service Insertion | Networking & Content Delivery
AWS Cloud WAN service insertion - AWS Network Manager
AWS Cloud WAN introduces Service Insertion to simplify security inspection at global scale - AWS