Internet Gateways & Route Tables

Internet Gateways

• It is a horizontally scaled, redundant, and highly available VPC component that allows communication between your VPC and the internet.

• It serves two purposes:

  • Provide a target in your VPC route tables for internet-routable traffic.

  • Perform network address translation (NAT) for instances that have been assigned public IPv4 addresses.

• You can only have 1 Internet Gateway per VPC.

Enabling internet access

1. Create an internet gateway.

2. Attach the internet gateway to your VPC.

3. Add a route to your subnet's route table that directs internet-bound traffic to the internet gateway.

4. Ensure that instances in your subnet have a globally unique IP address (public IPv4 address, Elastic IP address, or IPv6 address).

5. Ensure that your network access control lists and security group rules allow the relevant traffic to flow to and from your instance.

Route Tables

• A route table contains a set of rules, called routes, that are used to determine where network traffic from your subnet or gateway is directed.

Main Route Table

• When you create a VPC, it automatically has a main route table.

• The main route table controls the routing for all subnets that are not explicitly associated with any other route table.

• You cannot delete a main route table.