Cisco StackWise

Cisco StackWise is a technology offered by Cisco Systems that allows for up to nine Catalyst switch 3750 series switches to operate as though they were one 32-Gbit/s switch. This allows for greater resiliency, and performance.
One switch from the stack will act as the master switch. The master switch will maintain the stack and allow you to configure and monitor the whole stack as though one via a single console.
If one switch fails the remaining switches will continue to operate by looping back any information that would normally traverse the failed switch, effectively bypassing it. If the master switch fails, the next switch in the stack will automatically take over as master. This feature means greater redundancy, as one switch's failure will not bring about a failure of the entire stack.
As each switch contains the entire configuration for the stack one of the benefits of this technology is the ability to replace a down switch (any including master) with a new un-programmed switch. The stack will configure the new switch on the fly and allow for minimal downtime
StackWise effectively replaced the GigaStack found on lower-price models such as Catalyst 35xx and 29xx series.
Recently, there is a new variation of the technology, known as Cisco Stackwise Plus, offering 64Gbit/s nonblocking switching fabric speed.
Master Selection
The master switch of a stack is determined in the following order.
User specified.
The switch with the most advanced IOS, i.e. Advanced IP Services IPv6 (AIPv6), then Enhanced Multilayer Software Image (EMI) and then Standard Multilayer Software Image (SMI).
Programmed switch. A configured switch will preside over a switch with just the defaults.
Uptime. The switch that has been running the longest.
MAC address. The switch with the lowest MAC address.
Models

Like most Cisco product lines, the Catalyst Switch series evolves fairly rapidly. There are two general types of Catalyst switches: fixed configuration models that are usually one or two rack units in size, with 12 to 80 ports; and modular switches in which virtually every component, from the CPU card to power supplies to switch cards, are individually installed in a chassis.
As of 2011, the most popular fixed configuration switches are the WS-C2960, the WS-C3560 and WS-C3750 series at the high end, an entry level managed "express" series - with models beginning WS-CE (configurable by web interface only, no command line interface), the "ME" metroline series of switches, and a new "Small Business" series coming from Cisco's acquisition of Linksys. In addition, there are many excellent legacy switches suitable for most business and service provider needs no longer offered directly through Cisco (WS-C2950, WS-C3550 for example). Cisco fixed configuration switches come with a bewildering assortment of features (10/100 ports versus 10/100/1000 ports, some with power over Ethernet, some with varying types of gigabit and 10gig uplink ports, some with standard or enhanced software, varying power supplies) and it is difficult to tell what features a switch has (aside from the number of ports) from a visual inspection, and similar-appearing switches can have dramatically different features.
[edit]Cisco model names and switch features
In general, switch names start with WS-C, followed by the model line (2960). A letter at the end of this number signifies a special feature, followed by the number of ports (usually 24 or 48) and additional nomenclature indicating other features.
Cisco modular switches are much larger and are entirely configurable, beginning with a chassis, power supplies, the choice of supervisory engines (CPU mainboards), and switch modules. Among Cisco's modular series are:
The Cisco Catalyst 6500 Series is a chassis-based switch family. This series can support interfaces up to 10 Gigabit Ethernet in speed and redundant Supervisor modules.
The Cisco Catalyst 5500 Series and Cisco Catalyst 5000 Series is a chassis-based switch family. The Cisco Catalyst 5000 Series is acquired from another company. This entire series has now reached end-of-sale.
The Cisco Catalyst 4900 series is a fixed-configuration switch. Uplink interfaces are either SFP ports or 10 gigabit Ethernet, with 48 copper ports of 10/100/1000 Ethernet.
The Cisco Catalyst 4500 Series is a mid-range modular chassis based Switch manufactured by Cisco System.
The Cisco Catalyst 3000 and 3100 series switches are switches for use in blade-enclosures: the Catalyst 3032 is a Layer2 switch and the Catalyst 3130x and 3130G are blade-switches for the Dell M1000e enclosure.
The 1000 switch family is considered an edge device, having many functionalities that can be built as the device is very modular.


The inside of a Cisco 1900-series switch
1700: 24 10BaseT ports, 1 switchable MDI/MDIX uplink 10baseT/AUI/BNC port, and 2 Fast Ethernet ports. Runs neither CatOS nor IOS. Is a first-generation carryover from Cisco's acquisition of Grand Junction Networks.
19xx: 12 or 24 10BaseT ports and 2 Fast Ethernet ports. ISL trunking on the 100 Mbit/s ports. Runs neither CatOS nor IOS. It is in End-of-Life today.