Networking Basics

Here are some of the fundamental parts of a network:

Network- A network is a group ofcomputersconnected together in a way that allows information to be exchanged between the computers.
Node- A node is anything that is connected to the network. While a node is typically a computer, it can also be something like aprinterorCD-ROM塔。
Segment- A segment is any portion of a network that is separated, by a switch, bridge or router, from other parts of the network.
骨干- The backbone is the main cabling of a network that all of the segments connect to. Typically, the backbone is capable of carrying more information than the individual segments. For example, each segment may have a transfer rate of 10 Mbps (megabitsper second), while the backbone may operate at 100 Mbps.
Topology- Topology is the way that each node is physically connected to the network (more on this in the next section).
Local Area Network (LAN)- A LAN is a network of computers that are in the same general physical location, usually within a building or a campus. If the computers are far apart (such as across town or in different cities), then aWide Area Network(WAN) is typically used.
Network Interface Card (NIC)- Every computer (and most other devices) is connected to a network through an NIC. In most desktop computers, this is anEthernetcard (normally 10 or 100 Mbps) that is plugged into a slot on the computer'smotherboard.
Media Access Control (MAC) address- This is thephysicaladdress of any device -- such as the NIC in a computer -- on the network. The MAC address, which is made up of two equal parts, is 6byteslong. The first 3 bytes identify the company that made the NIC. The second 3 bytes are the serial number of the NIC itself.
Unicast- A unicast is a transmission from one node addressed specifically to another node.
Multicast- In a multicast, a node sends a packet addressed to a special group address. Devices that are interested in this group register to receive packets addressed to the group. An example might be aCiscorouter sending out an update to all of the other Cisco routers.
Broadcast- In a broadcast, a node sends out a packet that is intended for transmission to all other nodes on the network.

在下一个页面上,我们'll discuss some of the most common network topologies.