Types of Switches
Fixed configuration switches:-
These types of switches are fixed in their configuration. What that means is that you cannot add features or options to the switch beyond those that originally came with the switch. The particular model you purchase determines the features and options available. For example, if you purchase a 24-port gigabit fixed switch, you cannot add additional ports when you need them. There are typically different configuration choices that vary in how many and what types of ports are included.
Modular switches: -
These types of switches offer more flexibility in their configuration. Modular switches typically come with different sized chassis that allow for the installation of different numbers of modular line cards the line cards actually contain the ports. The line card fits into the switch chassis like expansion cards fit into a PC. The larger the chassis, the more modules it can support.
Stackable Switches
Stackable switches can be interconnected using a special back cable that provides high-bandwidth between the switches. Cisco introduced StackWise technology in one of its switch product lines. Stack Wise allows you to interconnect up to nine switches using fully redundant back plane connections. As you can see in the figure, switches are stacked one atop of the other, and cables connect the switches in daisy chain fashion. The stacked switches effectively operate as a single larger switch. Stackable switches are desirable where fault tolerance and bandwidth availability are critical and a modular switch is too costly to implement. Using cross-connected connections, the network can recover quickly if a single switch fails. Stackable switches use a special port for interconnections and do not use line ports for inter-switch connections. The speeds are also typically faster than using line ports for connection switches.
Difference between a Switch and a Hub