How to reduce the cost for public IP?

Question

Hello team,

From this month, Amazon going to charge for all public IP and Elastic IP which are associated or not. I have checked with below URL.

[https://aws.amazon.com/blogs/aws/new-aws-public-ipv4-address-charge-public-ip-insights/]()

We are running 1000+ ec2 instances with multiple VPC's across multiple regions in AWS account. All instances has public IP address.
For example

1. If EC2 Instances in public subnets with public IPs

**1000 EC2 instances -  1000 x 0.005 = 5 USD p/hour (1month x 5 = 3720 USD)**

2. If EC2 instances in private sunbets with NAT gateway

**1000 EC2 instances - 1000 x 0 = 0 USD p/hour (Because I dont need public ips)
50 VPC's - Each VPC has one NAT getway, then**

730 hours in a month x 0.045 USD = 32.85 USD (Gateway usage hourly cost)

10 GB per month x 0.045 USD = 0.45 USD (NAT Gateway data processing cost)

32.85 USD + 0.45 USD = 33.30 USD (NAT Gateway processing and month hours)

50 NAT Gateways x 33.30 USD = 1,665.00 USD (Total NAT Gateway usage and data processing cost)

one Elastic IP for NAT gateway - 1 month x 0,005 = 3.72 USD

**Total NAT Gateway usage and data processing cost (monthly): 1,665.00 USD**

Seems, If I go with NAT with private subnets for all my workloads, then it is cheaper than public ip's for my case. Am I right?

If I share the NAT gateway with other VPC's in same the region across account, then it will reduce the cost more. Right?

Is there any way to reduce the public ip cost ? Please correct If I'm wrong!

Accepted Answer

You're right. And you can reduce the NAT GW costs by using a shared egress VPC architecture. It would reduce the number of NAT GWs you need (less cost) but also allow you to deploy centralized egress filtering if that is something you would value from security perspective. Thing to keep in mind is that NAT GWs don't have infinite bandwidth, so you should keep an eye on usage.

* Business case for shared NAT GWs https://carriagereturn.nl/aws/vpc/nat/tgw/cost/saving/2022/02/07/sharing-natgw.html
* Shared egress VPC https://docs.aws.amazon.com/whitepapers/latest/building-scalable-secure-multi-vpc-network-infrastructure/centralized-egress-to-internet.html
* Monitoring NAT GW usage https://cloudonaut.io/nat-gateway-monitoring-with-cloudwatch-metrics-and-alarms/

Answer

Check out the blog post [Identify and optimize public IPv4 address usage on AWS](https://aws.amazon.com/blogs/networking-and-content-delivery/identify-and-optimize-public-ipv4-address-usage-on-aws/).  It covers the use of NAT gateway and ALB, and provides cost comparison with all public IP, among other items

How to reduce the cost for public IP?

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