Evaluating the "Interworking" Hardware

You will need to select one or more devices to tie together the servers and computers to allow the machines to "interwork." We called these machines by various names. For this discussion, we'll be more specific. But before explaining them, bear in mind that the previous discussion about server hardware components generally pertains to interworking hardware as well. That is, processor, memory, and disk capacity are as important for these machines as they are for servers. Here's a summary of these devices:

• Hub-This device sends data from one computer to all other computers on the network. It's a low-cost, low-function machine that usually operates at Layer 1 of the OSI model and ties together the computers attached to it through multiple (twisted pair or optical) ports. It acts as a repeater for a signal passed from, say, port 1 (through the repeater) to port 2. For Ethernet hubs, it participates in the collision detection operations, which can affect response time and throughput. In addition, the need for hubs to detect collisions restricts the size of the network and the number of hubs that can be installed.
  Don't overlook hubs; they're inexpensive and easy to install and maintain. However, they are declining in use.
• Switch-This term is one of the more confusing buzzwords in the industry. Because of its early use in telephone networks (the famous circuit switch) and packet networks (the famous X.25 packet switch), it has evolved though many years to have more than one meaning. First, it (now) is usually associated with a device that relays traffic by using a Layer 2 address. As examples, an Ethernet MAC address, or an ATM/MPLS label. Second, it usually contains software that supports the building of routing tables-a technique to improve traffic flow in a network, and a substantial improvement over a hub.
• Bridge-To confuse matters, the bridge performs the same operations as those just described for a switch. However, be careful here. The term bridge is often associated with a LAN device that uses Ethernet MAC addresses for routing. Thus, there's no such thing as an ATM or MPLS bridge. They're called Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) switches.
• Router-A router, is a more powerful device than a hub, switch, or bridge. Its principal operations are at OSI Layer 3 with IP addresses. High-end routers can also be configured as firewalls and extensive network management features. Some can be configured for their ports to operate as Layer 2 bridges. They are flexible and powerful machines.
• Wireless access point (WAP)-The WAP interworks the wired and wireless worlds. We learned that most WAPs operate with the IEEE 802.11 specifications. Many routers have the capacity to act as WAPs.

So, which do you choose? The decision depends on the size and geographical range of your user base. That stated, as a general practice, I opt for routers with WAP interfaces. You can purchase them for a modest price for a home network at your local office store or acquire them for a large enterprise network with a variety of capabilities.