AWS Architecture Guide for Cost-Effective Fixed Outbound IP Design

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If you want your retail trading platform to have dedicated fixed outbound IP addresses for each customer, using a Virtual Private Cloud (VPC) setup with NAT Gateways and Elastic IPs is a solid approach. This setup ensures each customer’s traffic always exits the network through their own fixed IP address, which is crucial for broker API whitelisting.

Start by creating separate VPCs or isolated subnets within a shared VPC for each customer. In each VPC or subnet, deploy NAT Gateways in the public subnet, and assign a unique Elastic IP address to each NAT Gateway. Then, configure the route tables in the customer’s private subnets so that all outgoing traffic is directed through their assigned NAT Gateway. This way, whenever your customer’s data leaves your network, it uses their dedicated fixed IP address.

For reliable operation, you should deploy NAT Gateways across multiple Availability Zones with separate Elastic IPs. If you opt for the regional NAT Gateway mode, it can automatically adjust across zones, reducing management workload while still providing the fixed IP addresses you need.

To improve scalability and control costs, consider grouping customers who have similar traffic patterns into shared VPCs. You can allocate dedicated subnets and NAT Gateways within these shared setups. NAT Gateway costs depend on hourly usage and data processed, so consolidating low-traffic customers can be cost-effective. Using tools like AWS IP Address Manager (IPAM) helps manage IP allocations centrally and automate IP management at scale. If you already own IP blocks, bringing your own IPv4 addresses can further reduce costs and streamline management.

Operational efficiency is key. Integrate IPAM with prefix list management to automatically track IP ranges and facilitate partner whitelisting. Share prefix lists through AWS Resource Access Manager with your broker partners to streamline the process of keeping IP addresses up to date. Centralized management of your IP pools ensures consistency and reduces manual work.

While NAT Instances might seem like an option, they are generally not recommended because they require more effort to manage, offer less reliability, and don’t scale as easily as managed NAT Gateways. Transit Gateways, meanwhile, are useful for connecting multiple VPCs but don’t directly address the need for fixed outbound IPs. Using EKS with routing at the pod level adds unnecessary complexity and may not offer the straightforward control you need.

For low-latency trading environments, a NAT Gateway setup offers consistent, high-performance, and scalable outbound connections. Deploy NAT Gateways in the same Availability Zone as your workloads to minimize latency. Choosing the regional NAT Gateway mode simplifies deployment across zones and ensures high availability without complicating your architecture. Regularly monitor NAT Gateway metrics and IPAM utilization to plan capacity and avoid bottlenecks.

This architecture can efficiently support hundreds or even thousands of customers, maintaining operational simplicity, cost predictability, and the fixed IP addresses essential for your broker API whitelisting process.

For more detailed guidance, you can consult resources on generating static outbound IP addresses using serverless methods, or building scalable IPv4 address management with AWS NAT Gateway in regional mode.