Task Computer Networks

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Task: Computer Networks
Your manager has asked you to prepare a 2 - 4-page written report including the following:

a) Address the following points as they relate to Ethernet:
Provide a diagram of an Ethernet packet.
Describe the frame format of a typical Ethernet packet.
Explain the significance of each field.
b) For Manchester, 4B/5B, and 8B/10B encoding, discuss the following:
the cable grades required for different speeds of Ethernet
efficiency and advantages
Explain how carrier sense multiple access with collision detection (CSMA/CD) works.
Ethernet performance as more hosts are added to a network

Answer:

a) Ethernet, being an easy and comparatively reasonable-priced medium of providing high-performance networking service to the existing computer system, is considered to be the mostly widespread LAN technology in the modern world.
Ethernet is a joint research product from Digital Equipment Corporation, Intel and Xerox: Xerox PARC invented the technology and Digital Equipment Corporation, Intel and Xerox jointly developed the idea and methodology. An Ethernet frame is typically a data packet on an Ethernet link. Every bit of information transmitted on an Ethernet network is conveyed in a packet; a packet is nothing but a chunk of data enclosed in few wrappers which eventually assist to detect the chunk of data and direct it to the right destination. Ethernet packets are often referred to as network frames because they add both a header and a trailer to the packets, thus framing the network data being transmitted. Below is a diagram of an Ethernet packet:

7 byte 1 byte 2 or 6 bytes 2 or 6 bytes 2 bytes 4-1500 bytes 4 bytes
Preamble Start
Frame Delimiter Dest.
MAC address Source
MAC address Length Data/Payload
(DSAP, SSAP, CTRL, NLI) FCS
Figure: An Ethernet Packet diagram
The frame format and significance of each field are described below:
Preamble
A typical Ethernet packet begins with 7 bytes of data know as preamble. The transmitted signals must need a proper clocking and preamble makes sure that it gets the clocking by delivering the proper synchronization and signal transitions. The preamble consists of 56 alternating 1s and 0s. Start Frame Delimter or SFD follows the preamble right away in the packet.
Start Frame Delimter
This is the next part after the preamble; it has the consistent format of: 10101011; and is used to specify the beginning of the frame information.
Destination MAC
This field represents the Media Access Control address of the machine that is in the process of receiving source machine's data. MAC address is of 6 bytes in length and stipulates the layer 2 physical addresses on the LAN. It is the physical address of a specific Network Interface Card, ...