Section 1 Basic Networking Knowledge CSIS 479R Fall 1999 “Network +” George D. Hickman, CNI, CNE

Objectives Define computer networking Define computer networking Contrast the features of the computing models Contrast the features of the computing models Compare LAN and WAN Compare LAN and WAN Identify basic network elements and describe the role of clients, servers, transmission media, and protocols Identify basic network elements and describe the role of clients, servers, transmission media, and protocols Identify the functions and features of the five basic network services Identify the functions and features of the five basic network services

Objectives (con’t) Describe network file services Describe network file services Describe network print services Describe network print services Describe network message services Describe network message services Describe network application services Describe network application services Describe network database services Describe network database services

Objectives (con’t) Identify the difference between centralized and distributed network architectures Identify the difference between centralized and distributed network architectures Identify the term transmission media as it relates to computer networks Identify the term transmission media as it relates to computer networks Identify the appropriate transmission media to meet a stated business need Identify the appropriate transmission media to meet a stated business need Identify the network connectivity devices and their functions Identify the network connectivity devices and their functions Identify the internetwork connectivity devices and their functions Identify the internetwork connectivity devices and their functions

Computer Networking Networking is the sharing of information and services Networking is the sharing of information and services Computer Networking provides the tools to allow computers to share information and resources Computer Networking provides the tools to allow computers to share information and resources

Computing Models Centralized computing Centralized computing –Mainframes and terminals Distributed computing Distributed computing –PCs do some processing, servers provide processing or other services Collaborative Computing Collaborative Computing –Multiple computers share the same task –Screensavers in our labs

Client/Server Computing Several Clients (PCs) are connected to a server Several Clients (PCs) are connected to a server Clients request services from servers Clients request services from servers Server performs some processing for client Server performs some processing for client

Client/Network Computing Network-centric rather than Server-centric Network-centric rather than Server-centric Services are requested from the network, rather than from a specific server Services are requested from the network, rather than from a specific server Requires a Directory service, such as NDS (Novell Directory Services) Requires a Directory service, such as NDS (Novell Directory Services)

LAN /WAN Local Area Network Local Area Network –Small group of computers interconnected –Transmission measured in mbps (megabits/second) –Communication media usually owned by LAN owner Wide Area Network Wide Area Network –Geographically dispersed –Transmission measured in kpbs (kilobits/second) –Communication media often leased from a provider

Special WANs Enterprise WAN Enterprise WAN –Connects LANs of a single Organization Global WAN Global WAN –Crosses national boundaries (may or may not cover entire globe) –Internet is an example

Required Network Elements Individuals who need to share something Individuals who need to share something –Network Services A method or pathway for contacting each other A method or pathway for contacting each other –Transmission media Communication rules to allow successful communication (2 way communication) Communication rules to allow successful communication (2 way communication) –Protocols like TCP/IP or IPX/SPX

Network Services Servers Servers –Service providers –Only provide services Clients Clients –Service requesters –Only request services Peers Peers –Provide and request services

Peer-to-Peer Networks Distributed network services using peers Distributed network services using peers –Window 3.x –Windows 95/98 –Windows NT Workstation –Windows NT Server –AppleTalk

Server-Centric Networks Strictly defined roles Strictly defined roles Clients request services Clients request services Servers provide services Servers provide services –NetWare –Banyon Vines –Open VMS

Transmission Media The pathway network signals take The pathway network signals take Often thought of as wires, but doesn’t need to be Often thought of as wires, but doesn’t need to be –Fiber Optic –Radio (atmosphere is media) –Infrared (atmosphere is media) Guarantees message delivery path, but not that messages will be understood Guarantees message delivery path, but not that messages will be understood

Protocols Rules that allow communication Rules that allow communication Can be one rule or a suite of protocols or rules Can be one rule or a suite of protocols or rules TCP/IP is a protocol suite TCP/IP is a protocol suite

Common Network Services File Services File Services Print Services Print Services Message Services Message Services Application Services Application Services Database Services Database Services

Network File Services Rapidly move files from place to place Rapidly move files from place to place Back up data Back up data Efficient use of storage media Efficient use of storage media Handle multiple copies of same files Handle multiple copies of same files

File Storage and Data Migration Online Storage Online Storage –Hard disks, etc. immediately available for use Nearline Storage Nearline Storage –Tape carousels, CD jukeboxes –Not immediately available, but no human intervention needed Offline Storage Offline Storage –Not immediately available, human intervention needed to use

File Storage and Data Migration File Archiving File Archiving Data Migration Data Migration Backups Backups –Moving data (often less-used or aged data in the case of migration) to offline, longer life, less expensive media.

File Update Synchronization When the same file exists in two or more locations, they can become out of sync When the same file exists in two or more locations, they can become out of sync Often occurs with laptops and portable devices Often occurs with laptops and portable devices File Update Synchronization identifies changes and manages file updates to maintain file system integrity File Update Synchronization identifies changes and manages file updates to maintain file system integrity Depends heavily on time stamps Depends heavily on time stamps

Network Print Services Network Applications that manage access to printers, fax machines, and copy equipment Network Applications that manage access to printers, fax machines, and copy equipment Useful to limit the number of printers required and to share specialized equipment Useful to limit the number of printers required and to share specialized equipment Handling multiple simultaneous requests (Queuing) Handling multiple simultaneous requests (Queuing)

Network Message Services Storing, accessing, delivering text, binary, graphic, digitized video, and audio data. Storing, accessing, delivering text, binary, graphic, digitized video, and audio data. Integrated and voice mail Integrated and voice mail Workgroup applications Workgroup applications

Network Application Services Network services that run software for clients. Network services that run software for clients. Different from file services because processing, not just files, is shared. Different from file services because processing, not just files, is shared. Specialization of servers Specialization of servers –Client-server database –PBX

Network Database Services Optimizes the computers that store, search, and retrieve database records Optimizes the computers that store, search, and retrieve database records Control where data is stored geographically Control where data is stored geographically Organize data logically between organizational departments Organize data logically between organizational departments Provide data security Provide data security Reduce database client access time Reduce database client access time

Distributed Data Database is divided into smaller parts, often managed by the department that owns the data Database is divided into smaller parts, often managed by the department that owns the data DBMS makes the whole database appear as a single, logical unit, and coordinates changes DBMS makes the whole database appear as a single, logical unit, and coordinates changes

Replication Multiple copies of data distributed throughout network Multiple copies of data distributed throughout network Provides faster access when users can access a closer copy of the database Provides faster access when users can access a closer copy of the database Provides fault tolerance since there is more than one copy in the event of loss of the master copy Provides fault tolerance since there is more than one copy in the event of loss of the master copy Requires a way of handling synchronization Requires a way of handling synchronization

Synchronization Methods Master Database Replication Master Database Replication –Changes can only be made to the master database –Replicas have read-only access Local Database Replication Local Database Replication –Changes can be made to the local copy of DB –All replicas must be able to communicate changes to all other replicas

Transmission Media Characteristics Characteristics –Cost –Ease of installation –Capacity –Attenuation –Immunity from interference (EMI, RFI) –Signal capture

Cable Media Twisted Pair cable Twisted Pair cable –Shielded or unshielded –Category 1-5 (Cat 3, Cat 5 common for data) Coaxial cable Coaxial cable –Like Cable TV cable, different resistance »75 Ohm RG-6 Satellite TV, RG-59 Cable TV »50 Ohm RG-8/11 Thick Ethernet RG-58 Thin Ethernet »93 Ohm RG-62 ARCnet Fiber Optic Cable Fiber Optic Cable –Glass or plastic fibers –EMI immune, allows faster transmission, greater lengths

Wireless Media Radiowave Radiowave –Shortwave, VHF and UHF Microwave Microwave –Terrestrial (earth-based) or Satellite Infrared Infrared –Point to Point or Broadcast

Spread Spectrum Radio Direct sequence modulation Direct sequence modulation –Figure 1-23 on page 1-81 –Signals send bits on rotating sequence on various frequencies Frequency hopping Frequency hopping –Figure 1-24 on page 1-81 –Signals send bytes (or other units) on rotating sequence on various frequencies

Transmission Media Connectors Attach directly to the transmission media Attach directly to the transmission media Provide physical interface between computing device and media Provide physical interface between computing device and media Figures 1-26 and 1-27 on page 1-98 Figures 1-26 and 1-27 on page 1-98

Network Interface Card A NIC is a NIC, not a NIC card A NIC is a NIC, not a NIC card Some use an adapter to allow different media to attach (Transmission media adapter) Some use an adapter to allow different media to attach (Transmission media adapter) Designed for a specific use Designed for a specific use –Don’t use a Token Ring NIC on an Ethernet LAN

Modem Modulator/DEModulator Modulator/DEModulator Converts computer’s digital signals to analog signals which can be used by phone/other systems Converts computer’s digital signals to analog signals which can be used by phone/other systems

Repeaters Used to overcome attenuation and extend transmission lengths Used to overcome attenuation and extend transmission lengths Amplifier type repeater amplifies all signals, including noise Amplifier type repeater amplifies all signals, including noise Signal Regenerating Repeater strips data out and retransmits it so noise is less of an issue Signal Regenerating Repeater strips data out and retransmits it so noise is less of an issue

Hubs Sometimes called concentrators or multiport repeaters Sometimes called concentrators or multiport repeaters Active Hubs Active Hubs –Regenerate or amplifies signals –Can extend cable length Passive Hubs Passive Hubs –Not a repeater (Cable TV splitter) Switches Switches –An Active hub that works like a bridge as well

Bridges Receives all signals on all segments they are attached to Receives all signals on all segments they are attached to Determines destination of each signal Determines destination of each signal Retransmits on other segments only those signals needing to “cross the bridge” Retransmits on other segments only those signals needing to “cross the bridge” Used to divide traffic on heavily used networks Used to divide traffic on heavily used networks

Multiplexers Allows users to use the entire transmission media bandwidth Allows users to use the entire transmission media bandwidth Combines two or more signals on a media segment Combines two or more signals on a media segment Often called a MUX Often called a MUX

Internetwork Connectivity Devices Routers Routers »Connect two or more logically separate networks »More processing intensive than bridges, so they don’t have as high of a throughput. (packets) »Provide Route Selection Brouters Brouters »Bridge & Router (Won’t drop unknown protocols) CSU/DSU CSU/DSU »Channel Service Unit/Digital Service Unit »Digital to digital “modem,” prepares signals for digital WAN links