PC Repair Tips

Ethernet was developed at Palo Alto Research Center (PARC) by Robert Metcalfe and David Boggs with Chuck Thacker and Butler Lampson early 1970. Xerox filed a patent application Ethernet in 1975. Today, Ethernet is based on the IEEE 802.3 (Institute of Electrical and Electronics Engineers). Metcalfe left Xerox in 1979 and founded 3Com to promote networks and personal computers. He convinced Digital Equipment Corporation (DEC) and Intel to work together to promote Xerox DIX (Digital / Intel / Xerox) Ethernet standard. Ethernet is the name of the invisible substance massless 19th century scientists believed that fills the universe. Ethernet was based on the same rules for polite conversation. Each team eager to transmit data waits until there is a pause in network traffic before attempting to transmit its data. This technology has been called CSMA / CD Carrier Sense Multiple Access Collision Detection and coaxial cables are used as transmission medium. Today, the Ethernet transmission uses full duplex on copper wires unshielded twisted pair or fiber optic cables with a system of schools and / or switches.

Ethernet operates at layer two of the model OSI Reference. Layer Two, also known as the data link layer is divided into Logical Link Control (LLC) layer and Media Access Control (MAC). Ethernet Nodes use a globally unique address of 48 bits called MAC address to communicate on a network. Datagrams are called level two frames. The management structure used Modern Ethernet is the same as previously used by the Ethernet coaxial cable networks, providing a level of compatibility.

The original Ethernet operated at a speed of three megabits per second. Today, transmission rates are typical of 10 Mbps Ethernet, 100 Mbps and 1000 Mbps (Gigabit Ethernet). 10,000 Mbps (10 Gigabit Ethernet) are now beginning. Faster data rates are still developing.

Ethernet Cable Standards

10-Base-2 also thinnet known as using a coaxial cable is limited to 10 Mbps and a maximum segment length of 185 meters. 10 Base-2 fell into disuse due to lower costs and greater simplicity associated with UTP (unshielded twisted pair) wiring.

10-Base-5, also known thicknet uses a coaxial cable is limited to 10 Mbps and a maximum segment length 500 meters. 10-Base-5 is more rare.

10-Base-T cable uses unshielded twisted pair (UTP) at a maximum of 100 meters (328 feet) at speeds of 10 Mbps 10-Base-T uses only two of the four child pairs in the cable.

10-Base-FL uses fiber optic lines up to 2000 meters with a flow of data up to 10 Mbps

100-Base-TX uses UTP cable, with a maximum segment length of 100 meters with a maximum flow of 100 Mbps 100-Base-TX uses two of the four child pairs in the cable.

100-Base-FX uses fiber optic cable with a maximum segment length of 2000 meters with a maximum data rate of 100 Mbps

1000-Base-FX using the cable optical fiber with a maximum segment length of 2000 meters with a maximum flow rate of 1000 Mbps (one gigabit per second).

1000-Base-TX using a UTP cable to a Maximum segment length 100 meters with a maximum flow rate of 1000 Mbit / s (gigabit per second). Unlike 100-Base-TX, 1000 Base-TX uses all four pairs of child cable.

Categories of copper wire

Although this is a total of nine categories of unshielded twisted pair (UTP) copper cable, actually there are only three likely to be found in your local network. The others are obsolete, or designed for use in backbone networks. The three categories are:

Category 5e: Provides performance of up to 100 MHz, and is frequently used for the 100 Mbps and Gigabit Ethernet.

Category 6: provides performance up to 250 MHz, more than double category 5 and 5e.

Category 6A: provides performance up to 500 MHz, twice the level 6 and is even suitable for 10 Gigabit Ethernet.

What should you use on your network?

Build your network with the fastest cable you can afford. Their bandwidth requirements will increase with time and retro-install your factory wires has long been disruptive and costly.

Copyright (c) 2008 Don R. Crawley

Don R. Crawley, Linux+ and CCNA-certified, is president and chief technologist at soundtraining.net, the Seattle training firm specializing in accelerated, task-oriented training for IT professionals. He works with IT pros to enhance their work, lives, and careers. For more information about learning opportunities with soundtraining.net, visit here.