Tackling the Networking Monster in the Cloud Era
In the early days of IT, networking was often a separate domain. If a networking task came up, you could simply pass it off to the network team. However, with the rise of cloud computing, especially platforms like AWS, this has completely changed.
As a Developer, SRE, or engineer, having a deep understanding of networking is now essential. There’s no escaping it—let’s dive in and tame the networking beast.
Virtual Private Cloud (VPC): The Starting Point
The journey in AWS infrastructure begins with creating a Virtual Private Cloud (VPC). This is where the magic happens. When you set up a VPC, the first thing you define is the CIDR (Classless Inter-Domain Routing). CIDR will be explained later, but it’s essentially the range of IP addresses you’ll use within the VPC.
Once your VPC is created, the next step is to define subnets. Subnets are smaller segments of the VPC’s IP address range, and each is tied to a specific Availability Zone (AZ). A key rule to remember: a subnet can only exist within a single AZ—it can’t span multiple zones.
IP Addressing: The Foundation of Communication
For your resources inside the VPC to communicate, they need IP addresses (IPv4 or IPv6). Think of it like giving your house an address so you can send and receive mail. Lets discuss IP addressing in a different post.
Routing: Controlling Traffic Flow
As the creator of the infrastructure, you get to control how traffic moves between subnets and resources using route tables. By defining routes, you dictate where and how data flows within your VPC.
Making Things More Complex: Gateways and Endpoints
Now that you have your VPC and subnets in place, let’s talk about connecting them to other networks, like the internet or AWS services. This is where Gateways and Endpoints come in.
- Gateway: Connects your VPC to an external network. For example, an Internet Gateway connects your VPC to the internet.
- VPC Endpoint: Allows your VPC to privately connect to AWS services without using the internet.
Connecting Multiple VPCs: Peering and Transit Gateways
If you end up with multiple VPCs and need to connect them, you can use a VPC Peering Connection. But what if you have many VPCs? Enter the Transit Gateway, which acts as a central hub to route traffic between your VPCs, VPNs, and AWS Direct Connects.
Troubleshooting: VPC Flow Logs
If things aren’t working as expected, the first place to look is your VPC Flow Logs. These logs will give you insight into the traffic flowing through your VPC and help you troubleshoot issues.
With cloud infrastructure, networking has become a critical part of every engineer’s toolkit. The more you understand it, the better equipped you’ll be to design, build, and troubleshoot in today’s cloud-first world.
