Three Operating Modes of Soft Routers in OpenWrt

Three Operating Modes of Soft Routers

Our current home networks generally consist of two configurations:

Single Optical Modem: The optical modem serves as the main router, providing all functions including optical signal conversion, dial-up internet access, NAT, DHCP, and basic wireless capabilities.

Network Topology:

Single Optical Modem Network Topology Diagram
Optical Modem + (Hardware) Router Combination: The optical modem works with one or more routers to share all the above functions.

Network Topology:

Optical Modem + Hardware Router Network Topology Diagram

At this point, if we want to add a soft router to an already established network environment, we need to consider the role that our soft router will play in the entire home network. Depending on the functions shared by the soft router, we can categorize its operating modes in the home network into three types: main router, one-arm router, and bypass router. Each operating mode has different connection methods in the home network.

Main Router

The configuration of the soft router as the main router has been explained in detail in previous texts, meaning that the soft router takes on all functions except for optical signal conversion and wireless capabilities. This allows us to perfectly achieve Principle One: all network control functions and permissions are centralized in one device, the soft router. However, to configure the soft router as the main router, two conditions must be met:

The optical modem must be in bridge mode, meaning it can only provide optical signal conversion.
The soft router must have two or more network ports, meaning it must have at least one lan port and one wan port.

Once the soft router is connected to the home network as the main router, the network topology diagram is as follows:

Main Router Network Topology Diagram of Soft Router

First, the optical modem needs to be switched from router mode to bridge mode, which means disabling dial-up and DHCP functions, and it is recommended to turn off the built-in Wi-Fi function, retaining only the optical signal conversion capability. Then, configure a static IP on the soft router’s lan port for logging into the soft router’s backend, and configure dial-up and DHCP functions on the wan port. Finally, switch the hardware router to AP mode (which is wired relay mode); in relay mode, the hardware router acts like a switch, providing only data forwarding and wireless functions. It is also important to note that routers in AP mode do not have a wan port, and more intelligent routers will automatically convert the wan port to a lan port when switched to AP mode.

One-Arm Router

The one-arm router may be the most difficult operating mode of the soft router to understand. If the soft router is still to take on all functions, the one-arm router is a variant of the main router, applicable to soft routers with only one network port. The author has not researched this extensively, so here is a brief introduction.

First, let’s look at the network topology diagram of the one-arm router:

One-Arm Router Network Topology Diagram of Soft Router

Why is the one-arm router considered a variant of the main router? Because the responsibilities of the soft router are essentially the same as those of the main router, taking on all functions except for optical signal conversion and wireless capabilities, but the soft router only has one physical network port. This port can simultaneously take on the roles of both wan and lan ports through VLAN technology.

It is important to note that not all instances of one-arm routers are variants of the main router. If we set the hardware router as the main router, then the one-arm router becomes a special secondary router that can provide Wi-Fi, firewall, and scientific internet access functions, which leads us to the third operating mode of the soft router.

Bypass Router

The bypass router is also a very popular operating mode for soft routers and has specific advantages compared to using the soft router as the main router.

Once the soft router is connected to the home network as a bypass router, the network topology diagram is as follows:

Bypass Router Network Topology Diagram of Soft Router

When we configure the soft router as a bypass router, we can think of it as a simple internet access device, but it performs the function of processing network data. In this case, we need to modify the computer’s internet IP to ensure it is in the same subnet as the soft router’s IP, then log into the soft router’s backend, modify the lan port IP to ensure the soft router’s address is in the same subnet as the main router, and set the soft router’s lan port gateway to the main router’s address (hardware router or optical modem), otherwise, data transmission will be interrupted at the soft router.

The biggest advantage of the bypass router mode compared to the main router mode is that configuring the soft router as a bypass router does not affect the main structure of the entire home network. This means that if the bypass router fails, the home network can still function normally, which is one of the most important reasons for the popularity of the bypass router.