Networking Essentials v2.0

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5.4.1 The Rise of Ethernet In the early days of networking, each vendor used its own proprietary methods of interconnecting network devices and networking protocols. If you bought equipment from different vendors, there was no guarantee that the equipment would work together. Equipment from one vendor might not communicate with equipment from another.

As networks became more widespread, standards were developed that defined rules by which network equipment from different vendors operated. Standards are beneficial to networking in many ways:

Facilitate design Simplify product development Promote competition Provide consistent interconnections Facilitate training Provide more vendor choices for customers There is no official local area networking standard protocol, but over time, one technology, Ethernet, has become more common than the others. Ethernet protocols define how data is formatted and how it is transmitted over the wired network. The Ethernet standards specify protocols that operate at Layer 1 and Layer 2 of the OSI model. Ethernet has become a de facto standard, which means that it is the technology used by almost all wired local area networks, as shown in the figure.

The figure shows a rectangle that identifies the proprietary vendor protocols from the 1970s as I B M, N C R, Xerox, D E C, and H P. An arrow points to another rectangle to the right that identifies the limited number of standards from the 1980s and 1990s as I E E E 802 dot 3 Ethernet, I E E E 802 dot 4 Arcnet, and I E E E 802 dot 5 Token Ring. An arrow points to another rectangle to the right that identifies the current winning standard as 802 dot 3 Ethernet.

Proprietary Vendor Protocols (1970s)Limited Number of Standards (1980s and 1990s)IBMAnd the Winner is:NCRXeroxDECHPIEEE 802.3 (Ethernet)IEEE 802.4 (ARCnet)IEEE 802.5 (Token Ring)IEEE 802.3 (Ethernet)

5.4.2 Ethernet Evolution The Institute of Electrical and Electronic Engineers, or IEEE (pronounced eye-triple-e), maintains the networking standards, including Ethernet and wireless standards. IEEE committees are responsible for approving and maintaining the standards for connections, media requirements and communications protocols. Each technology standard is assigned a number that refers to the committee that is responsible for approving and maintaining the standard. The committee responsible for the Ethernet standards is 802.3.

Since the creation of Ethernet in 1973, standards have evolved for specifying faster and more flexible versions of the technology. This ability for Ethernet to improve over time is one of the main reasons that it has become so popular. Each version of Ethernet has an associated standard. For example, 802.3 100BASE-T represents the 100 Megabit Ethernet using twisted-pair cable standards. The standard notation translates as:

100 is the speed in Mbps BASE stands for baseband transmission T stands for the type of cable, in this case, twisted-pair. Early versions of Ethernet were relatively slow at 10 Mbps. The latest versions of Ethernet operate at 10 Gigabits per second and more. Imagine how much faster these new versions are than the original Ethernet networks.

Drag the slider bar in the figure across the timeline to see how Ethernet standards have developed over time.

The animation shows a timeline of 1973, 198, 1983, 1985, 1990, 1993, 1995, 1998, 1999, 2002, 2006, 2009 2015, 2016, present. A table appears below the timeline with 3 rows: year, standard, and description. 1973, Ethernet, Ethernet invented by Dr. Robert Metcalf of Xerox Corp., 1980, D I X standard Ethernet II, Digital Equipment Corp., Intel, and Xerox (D I X) release a standard for 10 Mb/s Ethernet over coaxial cable, 1983 I E E E 802 dot 3 10 base 5, 10 Mb/s Ethernet over thick coaxial cable, 1985, I E E E 802 dot 3a 10 base 2, 10 Mb/s Ethernet over thin coxial cable, 1990 I E E E 802 dot 3i 10 Base t, 10 Mb/s Ethernet over twisted pair (T P), 1993, I E E E 802 dot 3j 10 base f, 10 Mb/s Ethernet over fiber optic, 1995, I E E E 802 dot 3u, 100Base – xx, Fast Ethernet: 100 Mb/s Ethernet over twisted pair (T P) and fiber (various standards), 1998, I E E E 802 dot 3z 1000 base – x, Gigabit Ethernet over fiber optic, 1999 I E E E 802 dot 3ab 100 base – T, Gigabit Ethernet over twisted pair, 2002, I E E E 802 dot 3ae, 10G base – xx, 10 Gb/s over fiber optic, 2006, I E E E 802 dot 3an 10G base T, power over Ethernet enhancements, 2009, 802 dot 3at (PoE), power over Ethernet enhancements, 2015, 100GbE and 40GbE, 100G / 40G for optical fiber, 2016 to present, 2.5GBase – T and 5GBase – T, 2.15 Gigabit and 5 Gigabit Ethernet over twisted pair.

Ethernet Evolution TimelinePresentYearStandardDescription19731980198319851990199319951998199920022006200920152016 to presentEthernetDIX standard Ethernet IIIEEE 802.3 10 BASE-5IEEE 802.3a 10 BASE-2IEEE 802.3i 10 BASE-TIEEE 802.3j 10 BASE-FIEEE 802.3u 100 BASE-xxIEEE 802.3z 1000 BASE-XIEEE 802.3ab 1000 BASE-TIEEE 802.3ae 10G BASE-xxIEEE 802.3an 10G BASE-T802.3at (PoE)100GbE and 40GbE2.5GBASE-T and 5GBASE-TEthernet invented by Dr. Robert Metcalf of Xerox Corporation.Digital Equipment Corporation, Intel, and Xerox (DIX) release a standard for 10 Mbps Ethernet over coaxial cable.10 Mbps Ethernet over thick coaxial cable10 Mbps Ethernet over thin coaxial cable10 Mbps Ethernet over twisted pair (TP)10 Mbps Ethernet over fiber opticFast Ethernet: 100 Mbps Ethernet over twisted pair (TP) and fiber (various standards)Gigabit Ethernet over fiber opticGigabit Ethernet over twisted pair10 Gbps over fiber opticPower over Ethernet enhancementsPower over Ethernet enhancements100G/40G for optical fiber2.5 Gigabit and 5 Gigabit Ethernet over twisted pair¹⁾

5.4.3 Video - Ethernet Addressing Play Video

5.4.4 The Ethernet MAC Address All communication requires a way to identify the source and destination. The source and destination in human communication are represented by names.

When your name is called, you listen to the message and respond. Other people in the room may hear the message, but they ignore it because it is not addressed to them.

On Ethernet networks, a similar method exists for identifying source and destination hosts. Each host connected to an Ethernet network is assigned a physical address which serves to identify the host on the network.

Every Ethernet network interface has a physical address assigned to it when it is manufactured. This address is known as the Media Access Control (MAC) address. The MAC address identifies each source and destination host on the network.

The animation has a topology consisting of a switch with links to four host PCs labeled, H1, H2, H3 and H4. H1 says I need to send information to H3. A frame appears on the screen of the PC and an expanded view of the frame appears above the PC. The frame consists of the framing addressing and data. The destination address CC:CC:CC:CC:CC:CC, the source address AA:AA:AA:AA:AA:AA and the data part of the frame is encapsulated. The frame from H1 is forwarded to the switch. The switch then forwards the frame out every interface but the interface connected to H1. When H2 and H4 receive the frame and they say This is not addressed to me. I shall ignore it. When H3 receives the frame it says This is mine.

This is not addressed to me. I shall ignore it.This is not addressed to me. I shall ignore it.This is mine.I need to send information to H3.Destination AddressSource AddressCC:CC:CC:CC:CC:CCAA:AA:AA:AA:AA:AAEncapsulated dataFrame Addressing

5.4.5 Lab - Determine the MAC Address of a Host In this lab, you will complete the following objectives:

Determine the MAC address of a Windows computer on an Ethernet network using the ipconfig /all command. Analyze a MAC address to determine the manufacturer. Determine the MAC Address of a Host 5.3 Network Communication Models 5.5 Communication Principles Summary

Alle Kommunikationsmethoden haben drei Elemente gemeinsam. Das erste dieser Elemente ist die Nachrichtenquelle oder der Absender. Nachrichtenquellen sind Personen oder elektronische Geräte, die eine Nachricht an andere Personen oder Geräte übermitteln müssen. Das zweite Element der Kommunikation ist das Ziel oder der Empfänger der Nachricht. Das Ziel empfängt die Nachricht und interpretiert sie. Das dritte Element wird als Übertragungsmedium oder Kanal bezeichnet. Es stellt den Pfad bereit, über den die Nachricht von der Quelle zum Ziel gelangen kann.

Bevor wir anfangen, miteinander zu kommunizieren, legen wir Regeln oder Vereinbarungen fest, die das Gespräch regeln. Diese Vereinbarungen umfassen Folgendes:

1. ? jeweils ein identifizierter Absender und Empfänger (3.transmission medium, or channel)
2. ? Kommunikationsmethode (persönlich, Telefon, Brief, Foto)
3. ? Gemeinsame Sprache und Grammatik Geschwindigkeit und Zeitpunkt der Zustellung
4. ? Bestätigungsstrategie Bestätigungs- oder Empfangsanforderungen Müssen wir bestätigen, dass unsere Nachrichten empfangen wurden?

Warum Protokolle wichtig sind?

Sowohl in einer kabelgebundenen als auch einer kabellosen Umgebung wird ein lokales Netzwerk als ein Bereich definiert, in dem alle Hosts „dieselbe Sprache sprechen“ müssen, was in der Computersprache bedeutet, dass sie „ein gemeinsames Protokoll verwenden“ müssen.

Protokollmerkmale

• Nachrichtenformat
• Nachrichtengröße
• Timing
• Kodierung
• Kapselung
• Nachrichtenmuster

RFCs for internet standards are published and managed by the IETF.

Es gibt kein offizielles Standardprotokoll für lokale Netzwerke, aber im Laufe der Zeit hat sich eine Technologie, Ethernet, durchgesetzt. Ethernet-Protokolle definieren, wie Daten formatiert und über das kabelgebundene Netzwerk übertragen werden. Die Ethernet-Standards spezifizieren Protokolle, die auf Schicht 1 und Schicht 2 des OSI-Modells arbeiten. Ethernet ist zu einem De-facto-Standard geworden, was bedeutet, dass es die Technologie ist, die von fast allen kabelgebundenen lokalen Netzwerken verwendet wird.

There is no official LAN standard protocol, but over time, Ethernet, has become more common than the others. Ethernet protocols define how data is formatted and how it is transmitted over the wired network. The Ethernet standards specify protocols that operate at Layer 1 and Layer 2 of the OSI model. Ethernet standards have evolved for specifying faster and more flexible versions of the technology. Each version of Ethernet has an associated standard. Each host connected to an Ethernet network is assigned a physical address which serves to identify the host on the network. Every Ethernet network interface has a physical address assigned to it when it is manufactured. This address is known as the Media Access Control (MAC) address. The MAC address identifies each source and destination host on the network.

Network Communication Models

A stack illustrates the protocols as a layered hierarchy, with each higher-level protocol depending on the services of the protocols shown in the lower levels. The separation of functions enables each layer in the stack to operate independently of others.

protocol models and reference models

internetwork reference model is the OSI model

The OSI model breaks network communications down into multiple processes. Each process is a small part of the larger task.

The protocols that make up the TCP/IP protocol suite can be described in terms of the OSI reference model. The functions that occur at the internet layer in the TCP/IP model are contained in the network layer of the OSI Model. The transport layer functionality is the same between both models.

~ consists of seven layers:

• 7 application
• 6 presentation
• 5 session
• 4 transport ²⁾
• 3 network
• 2 data link
• 1 physical ³⁾

• 5 6 7 Application
• 4 Transport
• 3 Internet
• 1 2 Network Access

Ethernet-Packet kann in der Regel 1514 Bytes groß werden. Sie schaffen so also 100 Pakete pro Sekunde a 1500 Bytes. 150kByte/Sek ist kein akzeptabler Wert. Erst wenn eine gewisse Größe überschritten ist oder keine eingehenden Pakete mehr kommen, sendet der Empfänger dann eine Sammelquittung:

https://www.msxfaq.de/netzwerk/grundlagen/tcp_retransmit_und_sack.htm

regelmäßigen Paketverlust teilweise ermitteln aber wenn ein Client 15MBit mit 1500byte Pakete überträgt, dann sind das 10.000 Pakete/Sek also 10 pro Millisekunde. Wenn ihr Netzwerk also nur 5ms „wackelt“, dann kostet das 50 Pakete

übermäßige Broadcasting-Anteil des NetBEUI am Gesamtverkehr innerhalb der Netzwerke

IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used initially on networks using the (since discontinued) Novell NetWare operating systems. They also became widely used on networks deploying Microsoft Windows LANs, as they replaced NetWare LANs, but are no longer widely used. IPX/SPX was also widely used prior to and up to Windows XP, which supported the protocols, while later Windows versions do not.

IPX ist ein Protokoll auf Netzwerkebene (Schicht 3 des OSI-Modells), während SPX ein Protokoll auf Transportschicht (Schicht 4 des OSI-Modells) ist. Die SPX-Schicht befindet sich auf der IPX-Schicht und stellt verbindungsorientierte Dienste zwischen zwei Knoten im Netzwerk bereit. SPX wird hauptsächlich von Client-Server-Anwendungen verwendet.