Networking Fundamentals

Introduction and OSI model

OSI ModelA Layered Approach To Manage Complexity

• Application Layer• Presentation Layer• Session Layer• Transport Layer• Network Layer• Data Link Layer• Physical Layer

CLASSIFICATIONSIntroduction

• LAN – Local Area Network

• WAN– Wide Area Network

• PAN– Personal Area Network

• MAN– Metropolitan Area Network

Classifications

TOPOLOGIESIntroduction

• Bus• Star• Ring• Mesh• Wireless• Hybrid

Topologies

NETWORK MODELSIntroduction

• Client/Server• Peer-to-Peer

Network Models

PROTOCOLSIntroduction

• TCP/IP• FIR• ATM• LLDP• NetBIOS & NetBEUI• HTTP• FTP• SMTP

Protocols

DEVICESIntroduction

• Media / Converters• NIC– Network Interface Card

• Repeater• Hub• Gateway• Bridge• Switch• Router

Devices

Hub

• Physical Layer• Box with lots of Ethernet connection sockets• Repeats messages to all connected nodes– Generates wasted traffic– Nodes must filter messages intended

for them

• Cheapest way to connect devices

Bridge

• Data Link Layer• Single incoming and outgoing ports• Keeps MAC address tables for two LAN

segments • Filters traffic using the MAC address

Switch

• Connects all nodes to each other like a hub • Examines Ethernet messages for destination

MAC address• Intelligently relays messages toward

destination• More expensive than hubs• Can be combined with hubs

Router

• Network Layer• A router connects to two different networks

Ex: LAN to WAN (internet)• Routers maintain a so-called routing table to

keep track of routes– Without routers the internet could not function– Uses the IP address to forward packets

Gateway

• Application Layer down to network layer• Connect and translate data between networks with

different protocols or architecture• For instance, allowing communication between TCP/IP

clients and IPX/SPX or AppleTalk• A gateway links two systems that do not use the same:– Communication protocols– Data formatting structures– Languages– Architecture

STANDARDS GROUPSIntroduction

• IEEE• ISO• W3C• CERN• UL• EIA• TIA• ANSI

Standards Groups

• IEEEInstitute of Electrical and Electronics Engineers

• ISOInternational Organization for Standardization

• W3CWorld Wide Web Consortium

• CERNEuropean Organization for Nuclear Research

• ULUnderwriters Laboratories

• EIAEnergy Information Administration

• TIATelecommunications Industry Association

• ANSIAmerican National Standards Institute

Standards Groups

OSI MODELIntroduction

• Application• Presentation• Session• Transport• Network• Data Link• Physical

OSI MODEL

Mnemonics to RememberTop Down:A Perfectly Simple Technology Narrowed Down PhysicallyAll People Seem To Need Data ProcessingAll Pros Search Top Notch Donut Places

Bottom Up:Programmers Like Networks That Seldom Postpone Anything*Programmers Dare Not Throw Salty Pretzels AwayPlease Do Not Throw Sausage Pizza AwayPlease Do Not Tell Sales People AnythingPeople Don’t Need To See Paula AbdulPeople Desperately Need To See Pamela AndersonPaula Did Networking 'Til She Passed Away

* Uses L for Link layer rather than D for Data Link