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From Microchip Technology, Inc.
AN1120 Ethernet Theory of Operation However, with ubiquitous deployment, internet Author: M. Simmons connectivity, high data rates and limitless range Microchip Technology Inc. expansibility, Ethernet can accommodate nearly all wired communications requirements. Potential applications include:INTRODUCTION • Remote sensing and monitoring This document specifies the theory and operation of ® • Remote command, control and firmware updating the Ethernet technology found in PIC MCUs with • Bulk data transfer integrated Ethernet and in stand-alone Ethernet • Live streaming audio, video and media controllers. • Public data acquisition (date/time, stock quotes, Ethernet technology contains acronyms and terms news releases, etc.) defined in Table 1. THEORY OF OPERATION APPLICATIONS Ethernet is a data link and physical layer protocol Ethernet is an asynchronous Carrier Sense Multiple defined by the IEEE 802.3™ specification. It comes in Access with Collision Detect (CSMA/CD) many flavors, defined by maximum bit rate, mode of protocol/interface, with a payload size of 46-1500 octets. transmission and physical transmission medium. With data rates of tens to hundreds of megabits/second, • Maximum Bit Rate (Mbits/s): 10, 100, 1000, etc. it is generally not well suited for low-power applications. • Mode of Transmission: Broadband, Baseband • Physical Transmission Medium: Coax, Fiber, UTP, etc. TABLE 1: ETHERNET GLOSSARY Term Definition CRC Cyclic Redundancy Check: Type of checksum algorithm used when computing the FCS for all Ethernet frames and the hash table key for hash table filtering of receive packets. DA Destination Address: The 6-octet destination address field of an Ethernet frame. ESD End-of-Stream Delimiter: In 100 Mb/s operation, the ESD is transmitted after the FCS (during the inter-frame gap) to denote the end of the frame. FCS Frame Check Sequence: The 4-octet field at the end of an Ethernet frame that holds the error detection checksum for that frame. IP Internet Protocol: Refers either to IPv4 or IPv6. LAN Local Area Network or Large Area Network. MAC Media Access Control: The block responsible for implementing the Media Access Control functions of the Ethernet specification. MAC Address A 6-octet number representing the physical address of the node(s) on an Ethernet network. Every Ethernet frame contains both a source and destination address, both of which are MAC addresses. MDI Medium Dependent Interface or Management Data Input. Products & Services
Ethernet extenders allow for network communication over distances longer than defined by the Ethernet standard.
Packet generators create a discrete chunk of communication in a pre-defined format.
Packet switching chips are communication integrated circuits (ICs) used in packet-switched networks to rout packets between network nodes.
Network equipment is used to split, switch, boost, or direct packets of information along a network. This product area includes network hubs, switches, routers, bridges, gateways, multiplexers, transceivers and firewalls. Often, network equipment is defined by is protocol or port type (e.g., Ethernet switch, USB hub).
Network repeaters regenerate incoming electrical, wireless or optical signals to preserve signal integrity and extend the distance over which data can travel. They are often used to connect cable segments in IEEE 802.3 networks.
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Topics of Interest
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Technical Articles
Ethernet Theory of Operation
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