Role of Switched Networks

A few years ago the flat Layer 2 switched networks were the standard. Flat Layer 2 data networks work on the basic principles of Ethernet and the common use of hub and repeaters to broadcast LAN traffic throughout a campus. As shown in Figure 1, networks have primarily changed to switched LANs in a hierarchical network. A switched LAN allows traffic management, additional flexibility, and extra features, such as:

• QoS


• Wireless network connectivity and support


• IP telephony and mobility services


• Additional security

Form Factors

Different types of switches are used in a business network. Considering common business requirement the appropriate switched equipment selection is a very important factor.  Selecting the type of switch the network administrator and designer must select a modular or fixed configuration and stackable or non-stackable. The physical installation is also an important consideration of the switch. The thickness of the switch decides where to install the switch. The switch can be installed in a rack or in a cabinet. These options are sometimes referred to as switch form factors, which I am going to explain below:-

Fixed Configuration Switches

Fixed Configuration switches are switches with a fixed number of ports and are normally not expandable. These switches do not support features or options further than those that originally came with the switch. The switch model determines the features and options available. Such as, if you have a 16-port gigabit fixed switch, you cannot add additional ports when you need them. This category is discussed in further detail below. Cisco Catalyst 2K, 3K, and the Cisco 300/500 series are good examples of Fixed Configuration switches. The Fixed configuration switch category is further broken down into:

• Unmanaged Switches


• Smart Switches


• Managed L2 and L3 Switches

Modular Configuration Switches

Modular switches are expendable switches comes with different sized chassis which allow a different number of modular line cards inside the chassis. The modular switches offer more flexibility in their configuration. If you have a 24 port modular switch you can easily expand the switch to 48 port.  

Stackable Configuration Switches

A stackable switch is a switch that is completely functional operating standalone but which can also be set up to operate jointly with one or more other switches in a group. This group of switches will show the characteristics of a single switch but have the port capacity of the sum of all switches. Stackable switches can be interconnected using a special cable that provides high-bandwidth throughput between the switches. The Cisco Stack Wise Technology allows the interconnection of nine switches in the group. These stacked switches effectively operate as a single larger switch.