During study about ‘CISCO’ devices, different kinds of Ethernet Standards & wiring will required to be come up first. Actually, Ethernet wiring is an essential subject on Cisco’s CCNA exam. So what do you need to know about Ethernet Standard & Cables?
Ethernet is a widely used LAN technology. It was invented at EXROX PARC (Palo Alto Research Center) in 1970s. Xerox, Intel and Digital defined it in a standard so it is also called DIX standard. The standard is now managed by IEEE in which 802.3 standard of IEEE defines formats, voltages of cable length etc.
The IEEE 802.3 Ethernet CSMA/CD architecture is based on the original DIX format established in the early 1980s by Digital, Intel, and Xerox. Current Ethernet networks uses a mixture of copper and fiber optic cabling. Ethernet standard recommends specific cable types and their lengths. So far this standard evolves as per need and requirement basis. New protocols are established. The naming structure of Ethernet standard assist to understand about its type and cable. For example 10Base5 is a 10 M/bits per second baseband transmission with a 500 meter distance limitation and 100BaseT is a 100 M/bits baseband transmission using category 5 unshielded twisted pair cable.
Common Ethernet Types
The 10Base5 standard is a linear bus topology design where all computers are connected through a shared cable. 10Base5 is baseband signal transmission, which uses entire bandwidth for signaling. Maximum length for every segment was 500 meters. It uses coaxial cable with 50 ohm resistance and AUI connectors. This standard is also known as Thicknet. It is inexpensive cable with great protection against EMI. However its negative side is “difficult to work as it takes up a lot of space and speed limit is 10 M/bit per second only. Because of this factor Thicknet has been phased out of networks.
The 10Base2 standard proposed in 1985. Signaling is baseband at speed of 10 M/bits per second. 10Base2 is baseband signal transmission. The 2 in 10base2 is representing maximum length for every segment would be 185 meters not 200 meter. It uses coaxial cable with 50 ohm resistance and T shape BNC connectors. This cable is less expensive and flexible than thick coaxial, which make it easier to install.
This standard published in 1990, used twisted pair cabling. 10BaseT has ability to use existing telephone cabling, frequently installed in buildings. It is low cost approach which can support different signal speeds depend on cable type. Twisting pairs of wires inside the jackets cuts down on the possibility of electromagnetic interference. Unshielded Twisted Pair cable is 100 ohm cable with 4 twisted pairs with maximum cable segment of 100 meter. UTP uses RJ-45 connector to connect devices and very flexible in design and easy to install and troubleshoot. UTP cables are divided into different categories according their characteristics:
- Cat-3 (16 M/bits per second)
- Cat-4 (20 M/bits per second)
- Cat-5 (100/1000 M/bits per second)
- Cat-6 (1000 M/bits per second)
Shielded Twisted Pair cable is also used in this standard for connecting devices. STP cable is a 150 ohm cable with 4 pairs.
100BASE-T (Fast Ethernet)
100base-T is same like 10Base-T with the difference of speed and full duplex capacity. It can send and receive packets simultaneously. Maximum cable segment distance is 250 meters. Fast Ethernet is defined IEEE 802u and has maximum capacity of 100 M/bits per second.
Gigabit standard is defined by IEEE802.ab and 803.3z. Gigabit Ethernet has a maximum capacity of 1000 M/bit per second. The maximum cable length is 100 meters. There are different physical layer standards for gigabit Ethernet using optical fiber (1000BASE-X), twisted pair cable (1000BASE-T), or shielded balanced copper cable (1000BASE-CX).