Network communication consists of packets of information being sent from one device to another. A large task, such as copying a huge file from one computer to another, can be broken down into thousands or millions of packets. A small task, such as a printer informing the network that it is on and ready to work, may only take one packet.
In a standard network, all packets passes through a central device. There are 3 basic types of central devices: hub, switch, and router. Each of these devices is designed for a specific purpose, but the distinction has become blurred in recent years. Many publications use the terms interchangeably, others use the term switch to refer to all of them. Some devices only do one thing at a time, others will do 2 or more things at a time. Some devices send all packets to every computer (or printer), and it is up to each computer to know if the packet is for it or not. The more efficient devices know which connected device needs what packets, and only sends data where it is needed.
The switch (or hub or router) has a number of ports. This number tells how many devices can be connected to it. Most ports have equal features, but some switches will have a couple of ports that run at a faster speed, and many have a port that is used to connect switches to each other.
Networks run at different speeds. Historically the speeds are given names like T10, T100 and T1000. A T10 network can send data at a maximum rate of 10 million bits per second, T100 at 100 million bits per second, and T1000 at 1000 million bits per second. T1000 is also called Gigabit. Some networks require all connected things to communicate at the same speed, others allow different devices to communicate at different speeds.
Networks have built in error checking. So, for example, when a packet is sent from one device to another there will be some form of feed back used to confirm that the data was properly received. If the data was not properly received, the packet is resent, sometimes at a slower speed. Such resending of data is common, and an error will not be reported to the user unless this resending happens too often.
Networks have many layers and components. We shall only concern ourselves with the 3 major parts: the computer (and other devices) connected to the network, the network device that controls the packets; and the wires that connect them. (Wireless networks are becoming popular. They are discussed separately.)
Macintosh computers and most PCs come equipped with ethernet ports. If you need to add a network board (or replace an existing one) we strongly suggest going with a major vendor, they strive to make sure they are compatible with the latest standards.
Computers often support multiple speeds, such as T10/T100. This means that the computer is capable of communicating at any of the listed speeds, and will communicate as fast as the network will allow. Thus a T10/T100 computer will communicate at T10 speeds if connected to a T10 hub, but it will communicate at T100 speeds if connected to a T100/T1000 switch.
Network devices come in many varieties. They support different numbers of ports, have different speeds, different switching features, and may or may not require operator support. Every machine that is going to be on the network needs its own port. This includes computers, servers, and printers.
Network devices follow the standard rule for hardware: faster costs more, as do additional features! Hubs and switches are functionally equivalent; the primary difference is that switches are far more efficient than hubs. The price difference between them has reduced to the point that an inexpensive switch is not that more expensive than a hub with the same number of ports. The third device is called a router, and it is used to join 2 or more networks.
Switches can communicate with different devices at different speeds. They can also multi-task, so the transfer of a gigabyte file from one computer to another will not slow down the other users who are not involved in the file transfer. Some switches are called attended. This means that they require an operator to set things up, and to monitor performance. Such devices will increase network efficiency, but at the cost of staff resources.
Routers are defined as a device that connects 2 or more networks. A traditional use of routers would be to join two Ethernet networks (possibly in different cities or states) over a long distance line such as a satellite link. A more recent use of routers is to connect Ethernet networks to the internet. A very popular router features 4 ethernet ports and one internet port. Many organizations with small networks are finding that these devices provide all the network service they need. These devices are also very popular in home network environments.
The wires that connect computers to the network are rated in categories: 3, 4, 5, 5e and 6. The higher the number the faster they can transmit information. To support T100 speeds, all wires in the chain need to be Cat 5 or faster. To support T1000, all wires in the chain need to be Cat 5e or Cat 6. The use of slower speed wires will slow down all packets that need to pass through that wire.
One major expense in a wired (versus a wireless) network is the labor required to run the wires from the location where the switch will be, to the locations where the computers and printers are. To make the most of this necessary work we strongly suggest using the "fastest" wires that will support the network you have choosen. For example, if you have choosen a T100 network, use Cat 5e or Cat 6 wires. This way you can upgrade your network to T1000 later without having to replace all the wires.
Wireless networks are the computer's equivalent of the cordless telephone. They are very convenient since they don't need wires connecting everything. Their down side is that they are more expensive, slower and less secure than conventional networks. A person equipped with a wireless laptop could tap into a wireless network from a waiting room, adjoining office space, or from the parking lot across the street.
Networking is a constantly evolving technology. A few years ago a T1000 connection was quite expensive and not widely available. Now it is commonplace, and the next faster connections are being developed! Simple networks can usually be self installed, but networks with complex needs are best left to professional network designers.
Fortnight Software will be happy to work with you and your network designers to discuss the network needs of a database product.
Phone: (818) 773-4640 |
Last Updated: July 1, 2005