What Is the VNbus?The VNbus is a high-speed, virtual network bus (VNbus) that connects the VNswitch modules on the MultiSwitch 900 backplane. Three VNbuses are supported, each providing 400 Mb/s of bandwidth, for a total capacity of 1.2 Gb/s. Although three VNbuses are supported, the default configuration is for all the VNswitch modules within a single hub to connect to one VNbus. An important function of the VNbus is to allow virtual LANs (VLANs) to span across the modules in the hub. Each VNbus supports 63 VLANs. Another important function of the VNbus is to allow a VNswitch module that has its routing software enabled to serve as a router for one or more other VNswitch modules in the hub. For a more detailed overview of the VNbus, refer to Chapter 3 of the DIGITAL VNswitch 900 Series Technical Overview. |