NetEngine AR V300R019 CLI-based Configuration Guide - Security
Firewall Working Mode
To improve networking flexibility, a firewall device defines the working mode of each interface but not the entire device. An interface has the following modes.
Routed Mode
A device is located between the internal network and the external network. On the device, the interfaces connecting to internal network and external network are assigned IP addresses on different network segments. The network topology needs to be changed.
As shown in Figure 6-1, two zones are configured on the device, Trust zone and Untrust zone. The interface in the Trust zone is connected to the internal network, and the interface in the Untrust zone is connected to the external network.
Note that, the interfaces in the Trust zone and Untrust zone locate in different subnets.
When forwarding packets among the interfaces in Layer 3 zones, the device searches the routing table according to IP addresses of packets. The device is similar to a router in this case. However, unlike a router, the device filters the packets and determines whether to allow them to pass according to the session table or ACL rules. In addition, the firewall takes other attack defense measures.