It is all about features, and the quality of the device.
You can usually check the quality of the device by looking for reviews for that particular device.
Features you want to look at
- Port count, and link speed for each port
- Remote administration features. How will you configure the switch, http, https, ssh, telnet, proprietary tool.
- The bandwidth of the backplane. A switch should be able allow for lots of simultaneous conversations. For a 1GB, you might expect to see a 10GB backplane.
- VLAN support, this allows you to have multiple virtual networks.
- Etherchannel/Bonding/Link Aggregation. It is possible to merge many ports into a single trunk.
- Routing/Firewalling L3 features. These days, many advanced switches including routing functionality.
- Quality of Service (QoS), if you will be using Voip, having QoS is pretty much required.
- Stackability, Many switches can be stacked using a special cable which allows them to be managed as a single unit.
- POE, some types of devices like phones can be powered by a switch.
If you have a small network, you probably don't really need most of the features, and a simple inexpensive switch will be fine. If you have high security demands, a VoiP system, a complex network, you'll need more features.
Unmanaged switches — These switches have no configuration interface or options. They are plug-and-play. They are typically the least expensive switches, found in home, SOHO, or small businesses. They can be desktop or rack mounted.
Managed switches — These switches have one or more ways, or interfaces, to modify the operation of the switch. Common management methods include: a serial console or Command Line Interface accessed via telnet or Secure Shell; an embedded Simple Network Management Protocol SNMP agent allowing management from a remote console or management station; a web interface for management from a web browser. Examples of configuration changes that one can do from a managed switch include: enable features such as Spanning Tree Protocol; set port speed; create or modify VLANs, etc.
Two sub-classes of managed switches are marketed today:
Smart (or intelligent) switches — These are managed switches with a limited set of management features. Likewise "web-managed" switches are switches which fall in a market niche between unmanaged and managed. For a price much lower than a fully managed switch they provide a web interface (and usually no CLI access) and allow configuration of basic settings, such as VLANs, port-speed and duplex.[10]
Enterprise Managed (or fully managed) switches - These have a full set of management features, including Command Line Interface, SNMP agent, and web interface. They may have additional features to manipulate configurations, such as the ability to display, modify, backup and restore configurations. Compared with smart switches, enterprise switches have more features that can be customized or optimized, and are generally more expensive than "smart" switches. Enterprise switches are typically found in networks with larger number of switches and connections, where centralized management is a significant savings in administrative time and effort. A Stackable switch is a version of enterprise-managed switch.
Source: http://en.wikipedia.org/wiki/Network_switch
I would explain in more personal detail, but the wiki explains it pretty well.
Best Answer
This is called MAC flooding. A "MAC address" is an Ethernet hardware address. A switch maintains a CAM table that maps MAC addresses to ports.
If a switch has to send a packet to a MAC address not in its CAM table, it floods it to all ports just like a hub does. So if you flood a switch with a larger number of MAC addresses, you will force the entries of legitimate MAC addresses out of the CAM table and their traffic will be flooded to all ports.