Learning @ Micro-Ctrl.
Micro-Ctrl – Network Basics – Everything you need to know.
This guide won’t teach you all the ins & outs of networking. It will however, give you the basic understanding on PC networking.
Essentially, a network is the means by which we connect people, enabling them to communicate with each other and share information using computers.
At the heart of every network beats the PC. Most of these PCs are user desktop systems, also called clients, that access another system’s network resources for file ac cess, print services, email and so on. A Client system typically doesn’t provide any services to other clients on the network. A network can encompass just a handful of clients systems, or it can link hundreds of thousands.
A server is any system that provides network-based services to the (client) users on the network. Usually, a network will have more than one server. Most servers offer some sort of security or protection against unauthorized use, for example, logins, passwords and group access rights.
A non-dedicated server is a system that can both access and be accessed by other systems on the network. In other words, it acts as both a client and a server, thus, it typically has all the characteristics of a client and a server.
More often , you find that servers are dedicated. This doesn’t mean they’re committed, just that they’re designed for a specific function or application. Some of the resources typically provided by a server include:
File server
Print server
Database server
Mail server
Internet server
Intranet server
Virtual terminal (VT) server
Remote execution server
Remote boot server
Any system that needs to be linked to a network requires a LAN adapter to be installed. A LAN adapter, also called a network interface card or NIC, is a hardware device that enables a PC to communicate over the network wiring and thus share resources. Adapters come in a variety of configurations, depending on which LAN access method, network cabling and system bus they support. The most popular adapters for today’s latest generation of processors support Category 5 cabling and the PCI bus.
Hubs are key components of the network infrastructure. A hub is a multi port hardware device that connects the network wiring between multiple nodes in a star configuration. This configuration has a hub at the center and cables radiating out from it to each node. Hubs allow multiple clients and servers at a site to connect to the network in one central location. The nodes connected to the hub’s ports share the 10Mbps or 100Mbps or 1000Mps bandwidth of the wire. Some hubs are stackable, enabling multiple connections at a lower cost per port. Stackability also provides scalability as the network grows.
Hubs can be passive, in which case they simply pass data through, or they can be active, in which case they regenerate the data to keep the signal strong. (Active hubs are sometimes called multi-port repeaters or switches.) Hubs may also be managed or unmanaged. If they're managed, they can monitor and report on the traffic that passes through them, as well as identify problems with faulty nodes.
A switch is a multi-port hardware device that receives incoming data at one port, stores it temporarily, then sends it back out to another port. The switch forwards data from a source to a destination based on address information included with incoming data. Switches can be used to segment LANs (and thus optimize network performance), to connect different LAN's or extend the collision diameter of a LAN.
Unlike hubs, which share bandwidth, switches provide dedicated bandwidth on each port at full wire speed.
A Router is a hardware device that stores and forwards network data between LANs and WANs. It connects LANs at the Network Layer ( Layer 3 of the OSI model) and supports the protocols required to route messages expediently from source to destination. Routers read the address information included with incoming data, then decides on the best path. Typically deployed on larger networks, routers can be used to improve network segmentation, route data between dissimilar LANs or route data to a WAN.
A bridge is a hardware/software device that connects local or wide area networks of dissimilar configurations, using the Data Link Layer protocol. It forwards complete packets between the networks.
LAN Access Methods:
Ethernet is by far the most widely deployed LAN access method today. A shared media technology, Ethernet broadcast packets to as many as 1024 nodes on a network segment via twisted pair, coaxial or fiber optic cabling.
Peer-to-peer networks are another type of PC LAN architecture. In this kind of network, each user PC doubles as a server. This provides the ability to share peripherals and resources with any other workstation. Peer-to-peer resource sharing can be effective on small networks, but security and reliability issues typically thwart its use in larger installations.
Network Cabling
The three most common wiring types you'll hear mentioned are:
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Twisted pair
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Fiber optic
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Coaxial
Twisted pair is a thin-diameter wire that arrived in the LAN world in the mid-1980s courtesy of the telephone companies, who commonly use it to wire standard phones. This type of cabling features two or more pairs of copper wires, each pair intertwined then wrapped to minimize electrical interference. Twisted pair cabling uses a modular RJ-45 connector. An RJ-45 connector is the nine wire version of that nifty little number that snaps into your phone and wall outlet.
Twisted pair wiring comes in two major varieties. Unshielded twisted pair (UTP) is the more popular of the two because it is more pliable, inexpensive and easy to install. Its only downside is limited immunity to noise. Shielded twisted pair (STP) wiring is wrapped in an extra layer of sheathing for better shielding against electrical noise, offering high-speed transmission.
Fiber Optic Cable (Category 7)
Fiber optic cable is the fastest of all the cables. However, it also turns out to be the most expensive. Using light to communicate it's susceptibility to electrical noise is zero. Using glass fiber optic cable allows very long distances between network nodes without any signal degradation.
WAN Cabling and ISDN
Any discussion of cabling in the WAN world needs to factor in ISDN (Integrated Services Digital Networks). ISDN is an international telephony standard for sending digitized voice, video and data signals over the public switched telephone system . It increases the amount of information that can be transmitted over regular phone lines, making ISDN a popular technology for remote LAN access and Internet connections.
ISDN supports speeds of up to 64kbps via a standard phone line, at a modest cost increase over regular phone call. ISDN service is widely available in many parts of the world. Routers and other communication devices connect to ISDN through either of the two standardized interfaces : Basic Rate Interface (BRI) and Primary Rate Interface (PRI). BRI and PRI services are typically ordered through a telephone company.
Network Operating Systems
A network operating system, or NOS, is the glue that holds the network together. Essentially, it is multi-user software that controls network resources, manages concurrent requests, oversees communication with other networks, and provides administrative tools and security for the network.
With a client/server NOS, a portion of the software is installed at each user PC (client). Another portion is installed at each server. Like a traffic cop, the NOS directs requests from client PCs to the appropriate resources, such as applications that reside at servers. The NOS also handles client communiqués to shared network devices, such as printers or modems.
Network operating systems come in a variety of flavours. As with software applications and hardware platforms, users demand and preference drive the marketplace. Today, only a relative few NOSs enjoy market predominance.
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Netware
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Windows NT Server
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UNIX
While you'll find that Netware and Windows NT tend to dominate the NOS world, you may also encounter less widely known NOS's.
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LANtastic
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LAN Manager
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LAN Server
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Banyan VINES
Strategic Networking Issues
Bandwidth:
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The enormous volume of traffic generated by today's powerful PCs.
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The Internet & intranets
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An increasing number of users
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Sophisticated desktop computing applications
These trends can strain the bandwidth of a typical LAN, creating bottlenecks and crippling productivity.
Manageability:
A number of vendors today are designing products around the client/server architecture. Ensuring interoperability and maintaining control over this increasing complex environment is becoming exponentially more difficult.
Total Cost of Ownership:
Reducing the total cost of ownership, or TCO, of PCs is a crucial concern in building networks today. To minimize these costs, companies need tools and strategies that make PCs and networks more manageable.
Security:
Companies are reaching out for information in ways no one could have imagined just a few years ago. As the Internet & WANs play an ever-larger role in a company's business, worries spiral about how to keep internal data secure against pilfering, tampering and viruses.
Applications:
Applications are becoming more sophisticated, complex, powerful, bandwidth-intense and business-critical. As if applications weren't enough, now everyone wants e-mail and desktop video conferencing.
Internet / Intranets
Companies are rushing en masse towards the internet, envisioning it as both the World Bank of Unlimited Information and the nirvana of global commerce. The past couple of years have also seen explosive growth in the phenomenon known as intranets. Intranets are networks within companies or organizations that use Internet technologies and protocols to improve productivity and share information.
WANs:
The standalone PC is rapidly becoming an artifact of a bygone era as more and more businesses jump on the WAN bandwagon. Remember that WANs aren't just those high speed global networks that link Multinational Corporations XYZ headquarters with its sites all over the world. Even small businesses that connect to the internet are tapping into a WAN.
Speaking the LAN-guage
10BASE-T: The IEEE 802.3i standard specification for 10Mbps Ethernet transmission over UTP wiring. using a star configuration with a hub at he center.
100BASE-T: The IEEE802.3u standard Ethernet specification for 100Mbps (Fast Ethernet) transmission using UTP cable.
Adapter: The device that connects a piece of equipment to the network and controls the electrical protocol for communication with that network; also called network interface card, or NIC.
Adaptive Technology: An Intel technology (supported in adapters and switches) that automatically and dynamically customizes product performance to match network operating conditions, thus helping to optimize network performance.
ATM (Asynchronous Transfer Mode:) A high-speed networking technology that transfers packets of data to transmit various kinds of information (voice, video, data)
Backbone: The part of the network that carries the heaviest traffic; it connects LANs, either within a building or across a city or region.
Bandwidth: The maximum amount of data that a network cable can carry, measured in bits per second (bps).
Baseband: A network transmission technique that uses voltage to represent data; similar to turning a light switch on and off.
Bridge: A device that connects two networks at the OSI Data Link layer and passes data between them; equivalent to a two-port switch.
Broadband: A network transmission technique that uses radio frequencies on a cable; a broadband cable is typically shared with other networks or services, such as TV or teleconferencing.
Browser: Client software used to search information posted on the Web; Netscape & Microsoft Internet Explorer are the most popular browsers.
Bus topology: The physical layout of a network in which all systems connect to a main cable; also known as linear bus.
Client: In a client/Server network, a node (or user workstation) on the network that uses resources provided by a server.
Coaxial cable: A network cable with good noise immunity; also known as coax or thicknet.
Collision Domain: The maximum length of the wiring media that allows collision detection; for example, the collision domain in Fast Ethernet using 100Base-TX is 205 meters.
CSMA/CD: The acronym for Carrier Sense Multiple Access with Collisions Detection; a LAN transmission technique implemented in Layer 2 of the OSI model and employed by 10Mbps Ethernet and Fast Ethernet.
Diskless workstation: A system on the network that boots up its operating system from a remote boot server, rather than locally.
Dumb terminals: A monitor and keyboard that displays information, only (as opposed to the processing capability of a PC); usually connected to a mainframe.
Fast Ethernet: The high-bandwidth networking technology based on the 802.3 Ethernet standard (100BASE-T); supports 100Mbps performance, a tenfold increase over original 10 Mbps Ethernet (10BASE-T) - 1000Base-T - now available.
FDDI: The acronym for Fiber Distributed Data Interface; a standard for fiber optic cable.
Fiber optic: A cable that uses light to communicate; the fastest and most noise resistant cable available for network wiring, but also the most expensive.
Frame Relay: A high speed. low latency packet switching technology, based on a switched virtual network topology. used for WAN's popular for Lan to Lan connections.
Full Duplex: Allows a packet to be transmitted and received at the same time.
Gateway: A network station used to interconnect two or more dissimilar networks or devices; may perform protocol conversion.
Gigabit Ethernet: A technology for 1 gigabit per second (1Gbps) Ethernet; equivalent to 1000Mbps and 10 times faster than fast Ethernet.
Half Duplex: Allows packets to be either transmitted or received, but not both at he same time.
Home Page: The main page of a Web Site and the first screen that visitors sees displayed when connecting to that site; usually has links to other pages, both within that site and to other sites.
HTML: HyperText Markup Language, the authoring language of the internet; used to create web pages.
Hyperlinks: Embedded "hot spots" in Web pages that allow users to jump from one document to another related document, regardless of where it "lives" on the internet.
Hub: The central wiring concentrator in a star configured network; useful for centralized management, the ability to isolate nodes from disruption, and extending the distance of Lan coverage.
IEEE: The Institute of Electrical and Electronics Engineers, a body that defines standards and specifications.
IP: Internet Protocol, the part of TCP/IP that governs packet forwarding.
IPX: Internet Packet Exchange, a Netware protocol that provides connectionless communications between devices on a network.
ISDN: Integrated Services Digital Network, a telecommunications standard for sending digitized voice, video and data signals over the existing public switched telephone network.
ISO: International Standard Organization, a body that promotes computer standards and developed the OSI model for network communication.
Local: Typically refers to devices attached to the user's workstation, as opposed to remote devices that are accessed through a server.
Local are network (LAN): Workstations and computers that are tied together in a specific work area in the same general location.
LocalTalk: Apple Computer's proprietary LAN, based on the AppleTalk architecture.
MAC: Media access Control, the IEEE specification for the lower sub-layer of the OSI Data Link Layer, CSMA/CD and token ring are types of MAC's.
Mac Address: Unique address assigned to each active infrastructure end station (including adapters, LAN on motherboards, switch ports and router ports.
MDI (Medium Dependent Interface): The predefined physical layer interface for 10Mbps Ethernet.
MIB: (Management Information Base): A database of objects that stores information used by SNMP-enabled management devices.
MII (Medium Independent Interface): The predefined physical layer interface for 100Base-T.
Networking Operating System: (NOS): Software that manages the resources of a network; typically provides file sharing, e-mail, print services, security measures, etc.
NIC: A Network interface card; see adapter.
Node: Each of the individual computers or other devices on the network.
OSI: Open System Interconnection, a LAN communication model developed by ISO.
Packet: A chunk of data bits and associated information, including source address and destination address, formatted for transmitting from one node to another.
Packet analyzer: A network diagnostic tool that hooks into a LAN and analyzes its traffic; capable of capturing a packet, examining it and breaking it down into its component parts of destination, origin, protocol, data etc.
Print server: An application specific computer that manages printers and requests for print services; allows multiple users to share a network printer.
Print Spooler: A software application, typically installed on a LAN server, that manages multiple print requests.
Protocol: Any defined set of procedures, conventions or methods that, when adhered to, allow two devices to interoperate; used to implement LAN services.
Remote boot: A firmware-based program in a network adapter that asks to have the workstation's operating system downloaded from a boot server on the network, used by networked diskless PCs.
Remote execution: The ability to run programs on remote systems; exporting time consuming processes to other systems frees up the local workstation.
