What is a Protocol? the communications between computers on a networkWritten by Gianfranco Fracassi
What is a Protocol? A protocol is a set of rules that governs communications between computers on a network. These rules include guidelines that regulate following characteristics of a network: access method, allowed physical topologies, types of cabling, and speed of data transfer. See Topology and Cabling sections of this tutorial for more information. The most common protocols are: Ethernet LocalTalk Token Ring FDDI ATM Ethernet The Ethernet protocol is by far most widely used. Ethernet uses an access method called CSMA/CD (Carrier Sense Multiple Access/Collision Detection). This is a system where each computer listens to cable before sending anything through network. If network is clear, computer will transmit. If some other node is already transmitting on cable, computer will wait and try again when line is clear. Sometimes, two computers attempt to transmit at same instant. When this happens a collision occurs. Each computer then backs off and waits a random amount of time before attempting to retransmit. With this access method, it is normal to have collisions. However, delay caused by collisions and retransmitting is very small and does not normally effect speed of transmission on network. The Ethernet protocol allows for linear bus, star, or tree topologies. Data can be transmitted over twisted pair, coaxial, or fiber optic cable at a speed of 10 Mbps. Fast Ethernet To allow for an increased speed of transmission, Ethernet protocol has developed a new standard that supports 100 Mbps. This is commonly called Fast Ethernet. Fast Ethernet requires use of different, more expensive network concentrators/hubs and network interface cards. In addition, category 5 twisted pair or fiber optic cable is necessary. Fast Ethernet is becoming common in schools that have been recently wired. Gigabit Ethernet The most recent development in Ethernet standard is a protocol that has a transmission speed of 1 Gbps. Gigabit Ethernet is primarily used for backbones on a network at this time. In future, it will probably be used for workstation and server connections also. It can be used with both fiber optic cabling and copper. The 1000BaseTX, copper cable used for Gigabit Ethernet, is expected to become formal standard in 1999. LocalTalk LocalTalk is a network protocol that was developed by Apple Computer, Inc. for Macintosh computers. The method used by LocalTalk is called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). It is similar to CSMA/CD except that a computer signals its intent to transmit before it actually does so. LocalTalk adapters and special twisted pair cable can be used to connect a series of computers through serial port. The Macintosh operating system allows establishment of a peer-to-peer network without need for additional software. With addition of server version of AppleShare software, a client/server network can be established. The LocalTalk protocol allows for linear bus, star, or tree topologies using twisted pair cable. A primary disadvantage of LocalTalk is speed. Its speed of transmission is only 230 Kbps.
| | How To Survive An Operating System CrashWritten by Patty Gale
"We apologize for inconvenience, but Windows could not be accessed or located."It happens to best of us. A complete operating system failure. One day you might turn on your p.c. and that dreadful message is on your screen as plain as day. You don't know what you could have possibly done, as your computer was working fine just a little while ago. Panic is usually first thing to set in. Something like an operating system failure can literally put home business owners out of business indefinitely. The cost and time involved in trying to repair a p.c. and months or even years of lost information is overwhelming and frightening to think about. This doesn't have to happen to you if you are prepared. When you think about it, our businesses are at mercy of technology. The technology is only as good as long as it's working properly. What a wonderful world we would live in if technology were flawless. The reality is that systems fail. Computers are machines and machines sometimes break down. It doesn't get any simpler that than. We have no other choice than to be prepared for when those times come, especially IF we want to make sure our home business suffers very little down time. There are some very easy things you can do right now to make ensure your peace of mind for your business. You need to be back up and running as quickly as possible in event of an operating system crash. 1. Document everything including usernames, passwords, merchant account numbers, important websites and especially software unlock codes. Anything that is not written down on paper is subject to be lost.
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