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AWS Outposts Fundamentals: Sizing and Network Considerations

You've identified AWS Outposts as a solution for a business need, now what do you do? Here are some thoughts on Outposts sizing and network considerations.

January 27, 2021 8 minute read

Once you have determined that AWS Outposts has the ability to meet one or more of your business needs, what are the next steps? What do you need to think about as you prepare to have AWS Outposts installed into your on-prem data center?

What is an AWS Outpost?

Put simply, an AWS Outpost is a fully managed service that allows you to host AWS infrastructure (compute and storage) and services (EC2, EBS, RDS, S3, EKS, etc.) in virtually any data center or on-premises facility. An AWS Outpost enables an organization to manage their on-premises environment using the same AWS tools, APIs and services they use in the cloud today and is ideal for:

  • Workloads that require low latency access to on-premises resources.
  • Local data processing.
  • Data resiliency.

Today, an AWS Outpost is delivered to you from AWS as a 42U rack that can be expanded to 96 racks should you need additional compute and storage capacity. Looking to the future, AWS announced at re:Invent 2020 that Outposts will be available in 1U and 2U small form factors for locations with limited space or environment capabilities in 2021. It will be exciting to see how the introduction of these systems impacts AWS Outposts delivery and design.

Yes, I agree! AWS Outposts is awesome, but don't rush the order…

Yes, AWS Outposts is awesome. And once you get a glimpse of how AWS Outposts can help you address critical business needs, that excitement can result in an overwhelming temptation to buy. I get it, I can feel the same way at times when buying a car — especially if it's a manual transmission sports car. The overwhelming temptation to satisfy my immediate “need” and purchase the car in front of me is very real. Even if the car doesn't meet the requirements of what I was looking for, satisfying the immediate need can cause me to gloss over important options, features, details or benefits… and the price! This is why I don't go sports car shopping alone.

You may be asking, what does this have to do with AWS Outposts? And that's a great question. Our Advanced Technology Center (ATC) is an “innovation ecosystem” that allows us to design, build and test the latest technology products and solutions. We are fortunate to have an AWS Outpost installed within the ATC, and we believe it can be a tremendous benefit to our customers.  

Why? We'll be your partner! We'll help to ensure that AWS Outposts is the right solution to address your business need. We can help you to determine what AWS Outposts options and features are optimal for your organization, and we'll help you to test and validate your use case. 

Why not try Outposts before you buy, ensuring the investment you make will provide the benefits you desire? You don't have to figure Outposts out on your own. Work with us to address some of the basic Outposts fundamentals, touched on below.

Will my application work on AWS Outposts?

To increase customer confidence in a solution, AWS created the AWS Outposts Ready designation to recognize solutions that have been tested and validated by AWS to work on AWS Outposts. If you're looking to deploy a third-party solution on Outposts, I suggest checking the AWS Outpost Ready partner portal to see if that partner and/or solution is listed.

But what happens if your preferred partner solution is not AWS Outposts Ready? What if you're planning on deploying an application or workload that has been developed in-house and will never be certified by AWS? Does this mean that AWS Outposts is not a viable solution? No, it does not mean that.  

It simply means that YOU are responsible for the testing, that YOU must do the necessary validation to ensure your workload will work properly on an AWS Outpost. As stated above, this is one of the many reasons why a partnership with WWT can provide an immense benefit to your organization.

Sizing an Outpost to support your initiative

After making the decision to use AWS Outposts to solve a business need, your first challenge will be to properly size AWS Outposts for your use case. Today, AWS Outposts are available in 22 pre-defined configurations with various combinations of EC2 instance capacity and EBS storage. You can see the available Outposts combinations by launching the AWS Outposts service dashboard from the AWS Management Console and then browsing the Outposts catalog.

On the Configurations screen, you’ll see the available Outposts configurations and can search for specific verbiage relevant to your use case. In this example, I searched the pre-defined configurations for “virtual desktops” and received a match with the Outposts resource ID OR-LMF5LJ1.

AWS Outposts configurations
AWS Outposts configurations

In terms of the OR-LMF5LJ1 configuration, the EC2 capacity is listed as (2) g4dn.12xlarge instances. However, this does not mean that you can only run (2) g4dn.12xlarge instances on this Outpost, but the value represents a measure of total system capacity.

If one of the pre-defined Outposts configurations cannot support the number or type instances required to support your workload, you can request a custom Outposts capacity configuration.

Request a custom AWS Outposts configuration
Request a custom AWS Outposts configuration

For AWS Outposts, It is vitally important to understand the system capacity requirements of your use case as you seek to properly size your Outpost, especially in terms of the 42U rack configuration that exists today. If you oversize your Outpost, you'll potentially be paying thousands of dollars per month for capacity you don't need, or may never need. If you undersize your Outpost, you may quickly exhaust your available capacity.  

Now, purchasing a second Outpost isn't unprecedented. In fact, it may be the optimal solution in some use cases. But being “forced” to obtain a second Outpost due to lack of planning will not be looked upon favorably as your organization, and its Outposts-related initiatives, must wait for a new Outpost to arrive. How much will that wait cost your business? 

The Outpost local gateway, NAT and system connectivity

When designing and considering network connectivity, it’s important to understand the function and purpose of the Outposts networking components, called the local gateway and the customer-owned IP address pool.

Each Outpost supports a single local gateway (LGW) which serves two purposes. First, any network traffic originating on an Outpost and destined for the local data center will use the LGW as the target for that traffic. Second, should a local resource communicate with an instance hosted on AWS Outposts, the LGW performs NAT for any instances that have been assigned an address from a customer-owned IP pool.

During the Outpost installation process, you are required to provide a CIDR block to serve as the customer-owned IP (CoIP) pool. This CIDR block is assigned to the LGW and is advertised to the on-prem network via BGP. IP addresses from this block are then assigned to resources on your Outpost.

Perhaps a simple example and diagram would be helpful to visualize the concept. As shown below, when the Outpost-based EC2 instance 172.16.3.23 communicates with the local data center, it will traverse the LGW and be translated to the CoIP of 10.23.7.44. When the communication is reversed, the traffic navigates the on-prem network using the CoIP and is translated back to the 172.16.3.23 address at the LGW to reach the Outpost instance.

Traversing the AWS Outpost local gateway with NAT
Traversing the AWS Outpost local gateway with NAT

What impact do the LGW and NAT have in regard to system connectivity? Using the AWS Outpost in the ATC will help answer this question, as the answer will likely “depend” (we love that word in IT) on the workload being deployed on Outposts. In performing our own testing, we have found that some applications require a proxy system capable of understanding alternate IP addressing to support AWS Outposts/on-prem connectivity.

Conclusion

AWS Outposts is a fantastic solution and capable of supporting a myriad of use cases. As we have discussed today, it's important to understand the use case to effectively size the Outpost and properly facilitate network connectivity — and in this manner, partnering with WWT can get you “ahead of the curve." 

Is there a scenario you'd like to test on Outposts, or would you just like to see it in action? Allow me to urge you once again to partner with WWT to use the AWS Outpost we have available in our ATC. Use the ATC and the WWT platform as a tool to help you address the challenges you are facing, and check back often as we plan to release content as new use cases arise and as Outposts continues to mature as a service offering.

Contact us at aws_alliance@wwt.com to learn more.

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