A switching chassis includes more than one cascade unit and more than one switching unit, where: the cascade units have cascade interfaces to connect line processing chassis; the switching units have switching ports to connect the cascade interfaces; and any cascade interface of any cascade unit is connected to one switching port of any switching unit. A router cluster with the above switching chassis includes switching chassis and line processing chassis interconnected via optical fibers, where: any optical interface of any line processing chassis is connected to one cascade interface of any cascade unit; and any cascade interface of any cascade unit is connected to one switching port of any switching unit. With the present invention, the capacity of a router cluster can be expanded without the need to replace any component of the router cluster so that the expansion cost is lower.