<http://lib.cnfolio.com/ENG653SwitchingArchitectures>
WAN and VLAN Solutions

Switching architectures



Division of labour principle


  1. Control plane functions include the system configuration, system management, maintenance of forwarding tables and maintenance of network topology information.
    • Less strict performance requirements
    • Not applied to every input frame
  2. Datapath functions include forwarding decisions, data transfer and data scheduling.
    • Very strict performance requirements
    • Applied to every input frame





Development of datapath architectural patterns



Shared bus




Shared bus, multiple CPUs




Dedicated processors




Crossbar




Architectural importance of fixed-size frames







Classification of switching fabrics


Time division architectures multiplex input frames and forward them through a single data path connecting all input and output ports.

Space division architectures have multiple data paths available between the input and output ports, in which a subset of the paths can transmit data simultaneously.





Shared bus architecture







Shared memory architecture







Basic crossbar architecture







Asymmetric crossbar architectures











Banyan-based switch architectures








Four types of banyan-based architectures


  1. shuffle exchange
  2. reverse shuffle exchange
  3. banyan
  4. baseline





Internal blocking may occur with banyan architectures







Batcher-banyan architecture to avoid internal blocking


A banyan switch can avoid internal blocking by using a pre-processing sorting network to:
  1. Concentrate input ports so that there are no idle ports between any two active input ports
  2. Sort destination addresses in either ascending or descending order









Clos multipath architecture











Stages of the Clos architecture have specific roles:

The integers n, m, and r determine the overall size of the Clos network.




Commercial products and research papers