Internal Backpressure for Onboard Crosspoint-Buffered Switches with Port Multiplexing

Onboard switching, as a core technology in satellite networks, offers robust support for the advancement of the Space–Air–Ground Integrated Network (SAGIN). The onboard switching fabric is tasked with achieving high-speed and large-capacity data exchange and ensuring service quality within the constraints of limited resources. However, the current onboard crossbar switching fabric is confronted with internal traffic congestion issues. To address this, this paper introduces an internal backpressure scheme for the crosspoint buffered switching. This scheme entails the incorporation of a buffer queue at the output port. Once an output queue reaches the maximum queue capacity due to traffic congestion, a backpressure (BP) signal is transmitted to the input end, thereby preventing the input port from sending data to the output port, alleviating crosspoint buffer overload. A validation and performance evaluation of various backpressure algorithms are conducted. The results demonstrate that the implementation of a backpressure mechanism in switching fabric can significantly reduce packet loss rate under network congestion conditions.