VPC subnet configuration for AWS Network Firewall
When you associate a firewall to your VPC, you must provide a subnet for each Availability Zone where you want to place a firewall endpoint to filter traffic. A common configuration is to have a firewall endpoint in each zone where you have customer subnets that you want to protect, but you can also have a firewall endpoint filter traffic from multiple zones. When you create the firewall, Network Firewall adds a firewall endpoint to each of the designated subnets. Each firewall endpoint uses the firewall's associated firewall policy configuration to filter traffic that you route through it.
To prepare your VPC for your Network Firewall firewall, in each Availability Zone where you want a firewall endpoint, create a subnet for the endpoint. Each subnet must have at least one IP address available. Your can't change the IP address type after you create the subnet.
Network Firewall supports up to 100 Gbps of network traffic per firewall endpoint. If you require more traffic bandwidth, you can split your resources into subnets and create a Network Firewall firewall in each subnet.
Note
Reserve these firewall subnets for the exclusive use of Network Firewall. A firewall endpoint can't filter traffic coming into or going out of the subnet in which it resides, so don't place other applications in the firewall endpoint subnets.
For information about managing subnets in your VPC, see VPCs and subnets in the Amazon Virtual Private Cloud User Guide.
When you create your Network Firewall firewall, you must provide at least one zone and subnet for the firewall configuration. You can add and remove subnets after you create a firewall.
