Network Fundamental and its Components

What Is Networking?

In the simplest sense, networking means connecting computers so that they can share files, printers, applications, and other computer-related resources. The advantages of networking computers are fairly obvious:
● Users can save their important files and documents on a file server. This is more secure than storing them on workstations because a file server can be backed up in a single operation.
● Users can share a network printer, which costs much less than having a locally attached printer for each user’s computer.
● Users can share groupware applications running on application servers, which enables users to share documents, send messages, and collaborate directly.
● The job of administering and securing a company’s computer resources is simplified since they are concentrated on a few centralized servers. The above definition of networking focuses on the basic goals of networking computers together: increased manageability, security, cost-effectiveness, and efficiency over non-networked systems. However, we could also focus our discussion on the different types of networks, including
● Personal area networks (PANs), once the stuff of science fiction but rapidly becoming a reality as the mobile knowledge workers of today carry around an array of cell phones, Personal Digital Assistants (PDAs), pagers, and other small devices
● Local area networks (LANs), which can range from a few desktop workstations in a Small Office/Home Office (SOHO) to several thousand workstations and dozens of servers deployed throughout dozens of buildings on a university campus or in an industrial park
● Metropolitan area networks (MANs), which span an urban area and are generally run by telcos and other service providers to provide companies with high-speed connectivity between branch offices and with the Internet
● Wide area networks (WANs), which might take the form of a company’s head office linked to a few branch offices or an enterprise spanning several continents with hundreds of offices and subsidiaries
● The Internet, the world’s largest network and the “network of networks” On the other hand, we could also focus on the different networking architectures in which these various types of networks can be implemented, including
● Peer-to-peer networking, which might be implemented in a workgroup consisting of computers running Microsoft Windows 98 or Windows 2000 Professional
● Server-based networking, which might be based on the domain model of Windows NT, the domain trees and forests of Active Directory directory service in Windows 2000, or another architecture such as Novell Directory Services (NDS) for Novell NetWare
● Terminal-based networking, which might be the traditional host-based mainframe environment; the UNIX X Windows environment; the terminal services of Windows NT Server 4 Enterprise Edition; Windows 2000 Advanced Server; or Citrix MetaFrame Or we could look at the various networking technologies used to implement these architectures, including
● LAN technologies such as Ethernet, Token Ring, Fiber Distributed Data Interface (FDDI), Fast
Ethernet, Gigabit Ethernet (GbE), and the emerging 10G Ethernet (10GbE)
● WAN technologies such as Integrated Services Digital Network (ISDN), T-carrier leased lines, X.25, frame relay, Asynchronous Transfer Mode (ATM), Synchronous Optical Network (SONET), Digital Subscriber Line (DSL), and metropolitan Ethernet
● Wireless communication technologies such as the wireless LAN (WAN) standards 802.11a and
802.11b, and the consumer wireless technologies HomeRF and Bluetooth
● Cellular communication systems such as Time Division Multiple Access (TDMA), Code Division
Multiple Access (CDMA), Global System for Mobile Communications (GSM), and the emerging
3G cellular communication standards In addition, we could consider the hardware used to
implement these different networking technologies, including

● LAN devices such as repeaters, concentrators, bridges, hubs, Ethernet switches, and routers
● WAN devices such as modems, ISDN terminal adapters, Channel Service Units (CSUs), Data Service Units (DSUs), packet assembler/disassemblers (PADs), frame relay access devices (FRADs), multiplexers (MUXes), and inverse multiplexers (IMUXes)
● Equipment for organizing, protecting, and troubleshooting LAN and WAN hardware, such as racks, cabinets, surge protectors, line conditioners, uninterruptible power supplies (UPSs), KVM switches, and cable testers
● Cabling technologies such as coaxial cabling, twinax cabling, twisted-pair cabling, fiber-optic cabling, and associated equipment such as connectors, patch panels, wall plates, and splitters
● Unguided media technologies such as infrared communication, wireless cellular networking, and satellite networking, along with their associated hardware
● Data storage technologies such as redundant array of independent disks (RAID), network-attached storage (NAS), and storage area networks (SANs) along with their associated hardware, plus various enabling technologies, including Small Computer System Interface (SCSI) and Fibre Channel Or we could talk about various technologies that enhance the reliability, scalability, security, and manageability of computer networks, including
● Technologies for implementing network security, including firewalls, proxy servers, and virtual private networking (VPN), and such devices as smart cards and firewall appliances
● Technologies for increasing availability and reliability of access to network resources, such as clustering, caching, load balancing, Layer 7 switching, and terminal services
● Network management technologies such as Simple Network Management Protocol (SNMP), Remote Network Monitoring (RMON), Web-Based Enterprise Management (WBEM), Common Information Model (CIM), and Windows Management Instrumentation (WMI) Returning to a more general level, networking can also be thought of as the various standards that underlie the
different networking technologies and hardware mentioned above, including
● The Open Systems Interconnection (OSI) networking model from the International Organization for Standardization (ISO)
● The G-series, H-series, I-series, T-series, V-series, and X-series standards from the International Telecommunication Union (ITU)
● Project 802 of the Institute of Electrical and Electronics Engineers (IEEE)
● The Requests for Comment (RFC) series from the Internet Engineering Task Force (IETF)
● Various standards developed by the World Wide Web Consortium (W3C), the Frame Relay Forum, the ATM Forum, the Gigabit Ethernet Alliance, and other standards organizations Networking protocols deserve special attention in any definition of the word networking. These protocols include:
● LAN protocols such as NetBEUI, Internetwork Packet Exchange/Sequenced Packet Exchange
(IPX/SPX), Transmission Control Protocol/Internet Protocol (TCP/IP), and AppleTalk
● WAN protocols such as Serial Line Internet Protocol (SLIP), Point-to-Point Protocol (PPP), Point-to- Point Tunneling Protocol (PPTP), and Layer 2 Tunneling
Protocol (L2TP)
● Protocols developed within mainframe computing environments, such as Systems Network Architecture (SNA), Advanced Program-to-Program Communications (APPC), Synchronous Data Link Control (SDLC), and High-level Data Link Control (HDLC)
● Routing protocols such as the Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF) Protocol, and Border Gateway Protocol (BGP)
● Internet protocols such as the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Network News Transfer Protocol (NNTP), and the Domain Name System (DNS)
● Electronic messaging protocols such as X.400, Simple Mail Transfer Protocol (SMTP), Post Office Protocol version 3 (POP3), and Internet Mail Access Protocol version 4 (IMAPv4)
● Directory protocols such as X.500’s Directory Access Protocol (DAP) and the Lightweight Directory Access Protocol (LDAP)
● Security protocols such as Password Authentication Protocol (PAP), Challenge Handshake Authentication Protocol (CHAP), Windows NT LAN Manager (NTLM) Authentication, Kerberos, IP Security Protocol (IPsec), Secure Sockets Layer (SSL), and public key cryptography standards and protocols
● Serial interface standards such as RS-232, RS-422/ 423, RS-485, V.35, and X.21
We could dig still deeper and discuss the fundamental engineering concepts that underlie the various networking technologies and services previously discussed, including
● Impedance, attenuation, shielding, near-end crosstalk (NEXT), and other characteristics of cabling and other transmission systems
● Signals and how they can be multiplexed using time-division, frequency-division, statistical, and other multiplexing techniques
● Transmission parameters including bandwidth, throughput, latency, jabber, jitter, backbone, handshaking, hop, dead spots, dark fiber, and late collisions
● Balanced vs. unbalanced signals, baseband vs. broadband transmission, data communications equipment (DCE) vs. data terminal equipment (DTE), circuit switching vs. packet switching, connection-oriented vs. connectionless communication, unicast vs. multicast and broadcast, pointto- point vs. multipoint links, direct sequencing vs. frequency hopping methods, and switched virtual circuit (SVC) vs. permanent virtual circuit (PVC) We could also talk about the different types of providers of networking services, including
● Internet service providers (ISPs), application service providers (ASPs), and integrated communications providers (ICPs)
● Telcos or local exchange carriers (LECs), including both Regional Bell Operating Companies (RBOCs) and competitive local exchange carriers (CLECs), that offer such popular broadband services as Asymmetric Digital Subscriber Line (ADSL) and High-bit-level Digital Subscriber Line (HDSL) through their central office (CO) and local loop connection
● Inter-exchange carriers (IXCs) that provide popular WAN services such as dedicated leased lines and frame relay for the enterprise (large companies)
● Local loop alternatives including cable modems, fixed wireless, and satellite networking companies We could also list the various software technologies vendors have developed that make computer networking both useful and possible, including
● Network operating systems such as Windows, Novell NetWare, UNIX, and Linux
● Specialized operating systems such as Cisco Systems’ Internetwork Operating System (IOS), which runs on Cisco routers, and the variant of IOS used on Cisco’s Catalyst line of Ethernet switches
● Directory systems such as Microsoft Corporation’s domain-based Active Directory, Novell Directory Services (NDS), and various implementations of X.500 and LDAP directory systems
● File systems such as NTFS file system (NTFS) on Windows platforms and distributed file systems such as the Network File System (NFS) developed by Sun Microsystems for the UNIX platform
● Programming languages and architectures for developing distributed computing applications, such as the C/C++ and Java languages, Microsoft’s ActiveX and Sun’s Jini technologies, component technologies such as Distributed Component Object Model (DCOM) and COM+, inter process communication (IPC) technologies such as Remote Procedure Calls (RPCs) and named pipes, and Internet standards such as the popular Hypertext Markup Language (HTML) and the Extensible Markup Language (XML) family of standards
● Tools for integrating networking technologies in heterogeneous environments, such as Gateway Services for NetWare (GSNW), Services for Macintosh, Services for UNIX on the Windows 2000 platforms, and Microsoft Host Integration Server, all of which provide connectivity with mainframe systems On an even deeper level, we could focus on the various administration tools for managing networking hardware, platforms, services and protocols, including
● The Microsoft Management Console (MMC) and its various snap-ins in the Windows 2000 and
Windows .NET Server platforms
● The various ways routers and network appliances can be administered using Telnet, terminal programs, and the universal Web browser interface
● Popular TCP/IP command-line utilities such as arp, ping, ipconfig, traceroute, netstat, nbtstat, finger, and nslookup
● Platform-specific command-line utilities such as various Windows commands used for automating common administration tasks
● Cross-platform scripting languages that can be used for system and network administration, including JavaScript, VBScript, and Perl We could also look at various enterprise applications widely used in networked environments, including
● Enterprise Resource Planning (ERP) and Customer Relationship Management (CRM) platforms
● Enterprise Information Portal (EIP) and Enterprise Knowledge Portal (EKP) platforms
● The Microsoft .NET Enterprise Server family of applications that includes Microsoft Application Center Server, BizTalk Server, Commerce Server,Exchange Server, Host Integration Server, Internet Security and Acceleration Server, Mobile Information Server, and SQL Server I think that you can see by now that we could go on and on, slowly unpeeling our answer to the question “What is networking?” like the many layers of an onion. And it is pretty obvious by now that there is more to networking than just hubs and cables! In fact, the field of computer networking today is almost overwhelming in its breadth and complexity, and one could spend a lifetime studying only one small aspect of the subject. This has not always been the case. Let’s take a look now at how the field of computer networking has reached the amazing point where it is today.