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


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