Ethernet Technology and Ethernet Frame format

Ethernet technology is introduced by Xerox in 1970. Initially, it was introduced for Coaxial Cable but now we can use Twisted pair or Fiber optic cables. Standard name of Ethernet Technology is IEEE802.3

Ethernet Technology basically a LAN technology which describes the how data can communicate to other networking devices in same network segments.

Initially, it was operating data rate of 2-3 Mbps using CSMA/CD (Carrier Sense Multiple Access Collision Detect) over the Coaxial Cable.

Currently, data rates over Twisted pair and optical Fiber are:

  • 10-Base T
  • 100 Mbps- Fast Ethernet
  • 1000 Mbps- Gigabit Ethernet

Ethernet Technology basically works on both layer- Data-link and Physical Layer because it defines two type of transmission Packet and Frames.

Ethernet Frame format-

 

Frames contains lots of information-

Preamble– it has size of 7 bytes, used for data synchronization

Start of frame– It shows starting point and size is 1 byte.

Destination MAC Address– It has size of 6 bytes

Source MAC Address– It has size of 6 bytes

Length/Type– It has size of 2 bytes

Data– This field has a size of 42-1500 bytes, contain the actual data here.

FCS– it has a size of 4 bytes and used CRC for error detection.

 

Ethernet_Frame Format

 

Ethernet Cables:

There are 3 types of cable-

  • Twisted Pair- Twisted Pair cable consists of 2 or 4 pairs of copper wire in twisted form and these wires can’t do cross talk. Cross Talk is an error where one wire signal disturbs (Interference) to another wire.

There is 2 type of Twisted Pair cable-

Unshielded(UTP)- UTP uses in Ethernet network and telephone network. UTP is not shielded with any cover. In UTP wires are made from copper polyethylene with specific color codes. Colors of wires depend on, what purpose is making like AT&T made a cable for our Indoor Telephone Application with a distinct color pair like Blue-white, White-Blue, Orange white, White-Orange etc.

UTP cable mostly connects with the RJ-45 connector, RJ45 connector is an 8 Wire converter which uses in connect devices to network or ethernet.

UTP_Cable.jpg

Patch Cable

 

Main Categories for Twisted pair-

  • Cat3- support up to 10Mbps
  • Cat5- Support up to 100 Mbps
  • Cat5e- Support up to 1000Mbps
  • Cat6- Support up to 10 Gbps

 

  • Shielded(STP)- STP is shielded with a cover that is helping to protect for electromagnetic interference or cross talk. In STP, each cable of wires is wrapped with a Metallic Foil. STP cables are costly as compare to UTP, hence in market everyone using UTP cables.
  • Coaxial Cable: Coaxial Cable is made of a solid conductor which surrounded by a foil, insulator, and plastic. Insulator controls the signals and Foil are protected cable from electromagnetic interference. Coaxial cable is used to deliver the cable services in television.
  • Fiber Optical: Now a day, Fiber Optical cables are using for fast data transmission at  ISP or other service providers because this is reliable and the fast transmission and data are transferred in the form of signal.  In Fiber optical, data is transmitted in the form of light, that transfer the data as per the speed of light. That’s why this is the fasted cable for data transmission.

 Ethernet Topology:

  • Point to point Ethernet topology
  • Bus Ethernet topology
  • Star Ethernet topology

You can read more about topology in our old post.  Network Fundamentals and Topologies

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