Is the bandwidth of the Internet border firewall and NAT border firewall calculated separately?

Yes, the bandwidth of an Internet border firewall and a NAT border firewall can be calculated separately, depending on their deployment architecture and traffic handling roles.

Explanation:

1. Internet Border Firewall: This firewall typically sits at the edge of a network, directly facing the public Internet. It handles all inbound and outbound traffic between the internal network and the Internet. Its bandwidth is usually measured based on the total Internet-facing traffic, including web browsing, email, API calls, etc.

2. NAT Border Firewall: A NAT (Network Address Translation) firewall is often used to allow multiple internal devices to share a single public IP address when accessing the Internet. Its bandwidth is calculated based on the translated traffic passing through it, which may differ from the raw Internet traffic if NAT rules modify or aggregate flows.

In some cases, these firewalls are combined into a single device (e.g., a UTM or next-gen firewall with NAT capabilities), where the bandwidth is shared. However, in separate deployments, their bandwidths are independently measured.

Example:

• A company has a 1 Gbps Internet border firewall handling all external traffic.
• Internally, a 500 Mbps NAT border firewall translates traffic from 100 internal devices sharing 10 public IPs.
  Here, the Internet firewall's bandwidth is 1 Gbps, while the NAT firewall's bandwidth is 500 Mbps, calculated separately.

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