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LOCAL AREA NETWORKS-ETHERNET

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It is a Finnish book written by hannu jaakohuhta.

Day 1 Highlights:

  • 80 to 90 % of all estimated LAN are Ethernet based.
  • Token ring and FDDI are absolute

                                      Token ring : A token ring network is a local area network  in which all computers are connected in a ring or star topology and pass one or more logical tokens from host to host. Only a host that holds a token can send data, and tokens are released when receipt of the data is confirmed. Token ring networks prevent data packets from colliding on a network segment because data can only be sent by a token holder and the number of tokens available is controlled.

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Physically, a token ring network is wired as a star, with ‘MAUs’ in the center, ‘arms’ out to each station, and the loop going out-and-back through each.

A MAU could present in the form of a hub or a switch; since token ring had no collisions many MAUs were manufactured as hubs. Although Token Ring runs on LLC, it includes Source Routing to forward packets beyond the local network. The majority of MAUs are configured in a ‘concentration’ configuration by default, but later MAUs also supporting a feature to act as splitters and not concentrators exclusively such as on the IBM 8226.

MAUs operating as either concentrators or splitters.

 

 

Network Topologies:

In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines. There are two ways of defining network geometry: the physical topology and the logical (or signal) topology.

The physical topology of a network is the actual geometric layout of workstations. There are several common physical topologies, as described below and as shown in the illustration.

topology

In the bus network topology, every workstation is connected to a main cable called the bus. Therefore, in effect, each workstation is directly connected to every other workstation in the network.

In the star network topology, there is a central computer or server to which all the workstations are directly connected. Every workstation is indirectly connected to every other through the central computer.

In the ring network topology, the workstations are connected in a closed loop configuration. Adjacent pairs of workstations are directly connected. Other pairs of workstations are indirectly connected, the data passing through one or more intermediate nodes.

If a Token Ring protocol is used in a star or ring topology, the signal travels in only one direction, carried by a so-called token from node to node.

The mesh network topology employs either of two schemes, called full mesh and partial mesh. In the full mesh topology, each workstation is connected directly to each of the others. In the partial mesh topology, some workstations are connected to all the others, and some are connected only to those other nodes with which they exchange the most data.

The tree network topology uses two or more star networks connected together. The central computers of the star networks are connected to a main bus. Thus, a tree network is a bus network of star networks.

Logical (or signal) topology refers to the nature of the paths the signals follow from node to node. In many instances, the logical topology is the same as the physical topology. But this is not always the case. For example, some networks are physically laid out in a star configuration, but they operate logically as bus or ring networks.

DAY 2

FDDI:

FDDI provides a 100 Mbit/s optical standard for data transmission in local area network that can extend in range up to 200 kilometers (120 mi). Although FDDI logical topology is a ring-based token network, it did not use the IEEE 802.5 token ring protocol as its basis; instead, its protocol was derived from the IEEE 802.4 token bus timed token protocol. In addition to covering large geographical areas, FDDI local area networks can support thousands of users. FDDI offers both a Dual-Attached Station (DAS), counter-rotating token ring topology and a Single-Attached Station (SAS), token bus passing ring topology.

FDDI, as a product of American National Standards Institute X3T9.5 (now X3T12), conforms to the Open Systems Interconnection (OSI) model of functional layering using other protocols. The standards process started in the mid 1980s.FDDI-II, a version of FDDI described in 1989, added circuit-switched service capability to the network so that it could also handle voice and video signals.Work started to connect FDDI networks to synchronous optical networking (SONET) technology.

A FDDI network contains two rings, one as a secondary backup in case the primary ring fails. The primary ring offers up to 100 Mbit/s capacity. When a network has no requirement for the secondary ring to do backup, it can also carry data, extending capacity to 200 Mbit/s. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 mi). FDDI had a larger maximum-frame size (4,352 bytes) than the standard Ethernet family, which only supports a maximum-frame size of 1,500 bytes,allowing better effective data rates in some cases.

The FDDI data frame format is:

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Where PA is the preamble, SD is a start delimiter, FC is frame control, DA is the destination address, SA is the source address, PDU is the protocol data unit (or packet data unit), FCS is the frame check Sequence (or checksum), and ED/FS are the end delimiter and frame status.

 

Chapter One

Basic Principles

Network :

Image result for network diagram lan man wan MAN is also known as RAN- range area network

Network Operating system

Network Operating System (NOS)

Definition – What does Network Operating System (NOS)mean?

A network operating system is an operating system designed for the sole purpose of supporting workstations, database sharing, application sharing and file and printer access sharing among multiple computers in a network. Certain standalone operating systems, such as Microsoft Windows NT and Digital’s OpenVMS, come with multipurpose capabilities and can also act as network operating systems. Some of the most well-known network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, Linux and Mac OS X.

Network Operating System (NOS)

The salient features of network operating systems are:

  • Basic operating system features support like protocol support, processor support, hardware detection and multiprocessing support for applications
  • Security features like authentication, restrictions, authorizations and access control
  • Features for file, Web service, printing and replication
  • Directory and name services management
  • User management features along with provisions for remote access and system management
  • Internetworking features like routing and WAN ports
  • Clustering capabilities

Common tasks associated with network operating systems include:

  • User administration
  • System maintenance activities like backup
  • Tasks associated with file management
  • Security monitoring on all resources in the network
  • Setting priority to print jobs in the network

The term network operating system is used to refer to two rather different concepts:

  • A specialized operating system for a network device such as a router, switch or firewall.
  • An operating system oriented to computer networking, to allow shared file and printer access among multiple computers in a network, to enable the sharing of data, users, groups, security, applications, and other networking functions. Typically over a local area network (LAN), or private network. This sense is now largely historical, as common operating systems generally now have such features included.

 

Network operating systems can be embedded in a router or hardware firewall that operates the functions in the network layer (layer 3).[2]

 

CHAPTER 2

History of the Ethernet

Highlights:

1.in the course of 30 years Ethernet has evolved from a 4,800 bps radio link and connection based technology to a 10 Gbps optical fiber based data transmission technology.

2. A shared transmission path is fundamental idea behind Ethernet.

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Image result for Thick and thin ethernetImage result for Thick and thin ethernetImage result for Thick ethernet

Image result for Thick ethernetImage result for AUI connector

Image result for 10 base 5Image result for 10 base 5Image result for 10 base 2

Image result for 10 base 2

Thick Ethernet is Also known as 10 base 5 or thick net.

ETHERNET STANDARDIZATION

At the time when ethernet was introduced , it had several competitiors like

– MCA by data General

– HYPER channel by Network System corporation

– Attached Resource computer network (ARCnet) by Datapoint Corporation

– Omninet by corvus systems

The reason why Ethernet beat all of the players were its goal to develop into industry standard which is not tied to any manufacturer specific solutions.

DEC,Intel and Xerox(DIX group) decided to work together to develop ethernet. Soon Metcalfe resigned from his position at xerox and assumed the responsibility of full time collaboration negotiator. In 1980 the collaboration produced the ethernet blue book known as DIX Ethernet version 1.0. In version 1 speeed was 10 mbps.In summer of 1981 , 802.3 sub committee was developed for standardization task based on DIX group.

In 1983 intel, AT&T and NCR Corporation began developing a new interconnection method for Ethernet : Unshielded twisted pair(UTP). They decided to go for Star topology.This enabled the use of structural cabling, in which cables from individual workstations are connected to a central hub.

Image result for star topologyNetworking technologies #infografia #infographic http://arideocean.com: History-of-Ethernet

as the workstation ebolved, it became clear that 1Base-5 networkwere too slow and client did not trust starlan. When SynOptics released 10Mbps twisted pair Ethernet starlan was blown out of market.

Synoptic became 10Base-T standard.

Gigabit Ethernet

 

Intel PRO/1000 GT PCI network interface controller

In computer networking, Gigabit Ethernet (GbE or 1 GigE) is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second (1,000,000,000 bits per second), as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks, as a result of being considerably faster. The cables and equipment are very similar to previous standards and have been very common and economical since 2010.

Half-duplex gigabit links connected through repeater hubs were part of the IEEE specification,[1] but the specification is not updated anymore and full-duplex operation with switches is used exclusively.

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Medium Attachment Unit

From Wikipedia, the free encyclopedia

Two Medium Attachment Units or transceivers. (The units shown are backwards compatibility-oriented 10BASET MAUs, not the more typical 10BASE5 MAUs; cf. article.)

A Medium Attachment Unit (MAU) is a transceiver which converts signals on an Ethernet cable to and from Attachment Unit Interface (AUI) signals.

On original 10BASE5 (Thick) Ethernet, the MAU was typically clamped to the Ethernet cable. With later standards it was generally integrated into the network interface controller and eventually the entire Ethernet controller was often integrated into a single integrated circuit (“chip”) to reduce cost.

In most modern switched or hubbed Ethernet over twisted pair systems, neither the MAU nor the AUI interfaces exist (apart, perhaps as notional entities for the purposes of thinking about layering the interface), and the category 5 (CAT5) cable connects directly into an Ethernet socket on the host or router. For backwards compatibility with equipment which still has external AUI interfaces, MAUs are still available with 10BASE2 or 10BASETconnections.

The following standard, Fast Ethernet introduces division onto Media Access Controller (MAC) and Physical Layer Interface (PHY) layers connected with Media Independent Interface (MII). Some early Fast Ethernet hardware had a physical external MII connectors, functionally similar to AUI connector. However, the tradition of using a separate low-level I/O device in networking has continued in fast optical fiber network interfaces, where the GBIC, XENPAK, XFP, and enhanced small form-factor pluggable (SFP+) pluggable transceiver modules using the XAUI interface play a similar role.

Objectives of MAU:

  • Provide the physical means for communication between local network data link entities.
  • It defines a physical interface that can be implemented independently among different manufacturers of hardware and achieve the intended level of compatibility when interconnected in a common local network.
  • Provide a communication channel capable of high bandwidth and low bit error ratio performance.
  • Provide for ease of installation and service.
  • Provide for high network availability (ability of a station to gain access to the medium and enable the data link connection in a timely fashion).
  • Enable relatively low-cost implementations.

MAU Characteristics:

  • Enables coupling the Physical Layer Signalling (PLS) by way of the AUI to the explicit baseband coaxial transmission system.
  • Supports message traffic at a data rate of 10, 100, or even 1000 Mbit/s.
  • Provides for driving up to 500m of coaxial trunk cable without the use of a repeater.
  • Permits the DTE to test the MAU and the medium itself.
  • Supports system configurations using the CSMA/CD access mechanism defined with baseband signaling.
  • Supports bus topology interconnection.

Services provided by MAU:

  • Transmit.
  • Receive.
  • Collision detection and Loop-back functions direct transfer through the MAU.
  • The Jabber detect.
    • It removes equipment from the network whenever it continuously transmits for periods significantly longer than required for a maximum-length packet, indicating a possible problem with the NIC.
  • Signal quality error test.
    • The signal quality error test detects silent failures in the circuitry.
  • Link integrity functions
    • detects breaks in the wire pairs.
  • Both Signal quality error test and Link integrity functions assist in fault isolation.

Two modes of operation:

  • Normal mode:
    • The MAU functions as a direct connection between the baseband medium and the DTE. Data output from the DTE is output to the coaxial trunk medium and all data on the coaxial trunk medium is input to the DTE. This mode is the “normal” mode of operation for the intended message traffic between stations.
  • Monitor mode or Isolated mode:
    • The MAU functions as a receive-only connection between the baseband medium and the DTE. Data output from the DTE is suppressed and only data on the coaxial trunk medium is input to the DTE. This mode is for observing message traffic.

MAU functional specifications:

  • Transmit function
    • The ability to transmit serial data bit streams on the baseband medium from the local DTE entity and to one or more remote DTE entities on the same network.
  • Receive function
    • The ability to receive serial data bit streams over the baseband medium.
  • Collision Presence function
    • The ability to detect the presence of two or more stations concurrent transmissions.
  • Monitor function (Optional)
    • The ability to inhibit the normal transmit data stream to the medium at the same time the normal receive function and collision presence function remain operational.
  • Jabber function
    • The ability to automatically interrupt the transmit function and inhibit an abnormally long output data stream. It removes equipment from the network whenever it continuously transmits for periods significantly longer than required for a maximum-length packet, indicating a possible problem with the NIC.

MAU in this context is not to be confused with a Media Access Unit, which shares the same acronym.

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