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Network Theory – OSI and TCP/IP Models. Internetworking: An Overview. What is Networking?. Networking - the interconnection of workstations, peripherals, terminals and other devices*. Yesterday’s Networks. The advent of the desktop PC brought with it small, closed networks in the mid-1980s. - PowerPoint PPT Presentation
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@ONE Spring Hands-On Institute
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Network Theory – OSI and Network Theory – OSI and TCP/IP ModelsTCP/IP Models
@ONE Spring Hands-On Institute
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Internetworking:Internetworking:An OverviewAn Overview
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What is Networking?What is Networking?
• Networking - the interconnection of workstations, peripherals, terminals and other devices*
@ONE Spring Hands-On Institute
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Yesterday’s NetworksYesterday’s Networks
• The advent of the desktop PC brought with it small, closed networks in the mid-1980s.
An old-school LAN (local-area network)
@ONE Spring Hands-On Institute
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Today’s Computer NetworksToday’s Computer Networks
• Today, networks are everywhere:– School, work, home
– Coffee shops, airports, state parks
– Emerging technologies such as EV-DO and WiMAX promise metro-wide networks in the air.
@ONE Spring Hands-On Institute
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What happened?What happened?
• Over the past 20 years, computer networks have evolved:
Small, proprietary, closed systems
One huge, global, collection of networks (an internetwork)
The Internet
@ONE Spring Hands-On Institute
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What happened?What happened?
• Vendors realized that standardizing their products would help them make money.
• Various groups got together and proposed networking standards.
• The Internet (b.1969) offered an attractive de facto set of standards.
@ONE Spring Hands-On Institute
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Network Protocols and Network Protocols and StandardizationStandardization
@ONE Spring Hands-On Institute
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Network ProtocolsNetwork Protocols
• Early networks:– proprietary technologies– single vendor only
• Today:– Standards-based technologies– Macs, PCs, cell phones, watches, toasters, and
earrings can all share data as long as they all speak to each other according to the same set of rules, or protocol.
@ONE Spring Hands-On Institute
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Network ProtocolsNetwork Protocols
• Protocol - a set of rules, or an agreement, that determines the format and transmission of data.
SNA (Systems Network Architecture) = IBM
IPX (Internet Packet eXchange) = Novell
IP (Internet Protocol) = US Department of Defense
XNS (Xerox Network System) = Xerox
NetBEUI (NetBIOS Extended User Interface) = IBM
AppleTalk = Apple
DECnet = Digital Equipment Corporation
VINES = Banyan
@ONE Spring Hands-On Institute
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TCP/IP: Internet ProtocolTCP/IP: Internet Protocol
• One protocol has become the de facto standard for all computer networks.
• IP v4 = The Internet Protocol (version 4)• All hosts on the Internet use the IP protocol• The Internet actually uses a family, or suite, of
protocols called TCP/IP which includes:– TCP, or Transmission Control Protocol: (adds reliability
and sequencing to Internet conversations)– HTTP: (web stuff)– FTP: (file transfer)– DNS: (naming system that brought us .com and www)– SMTP: (mail, SPAM, and other delights of the Info Age)
@ONE Spring Hands-On Institute
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TCP/IP: Internet ProtocolTCP/IP: Internet Protocol
All of these devices use the TCP/IP protocol “stack” to communicate. In this case, they are using HTTP to browse the web.
All of these devices need an IP Address to be on the Internet.
TCP/IP’s developers never envisioned that this protocol could support a global network of entertainment and commerce.
@ONE Spring Hands-On Institute
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Reality CheckReality Check
• In the mid-1980s, Cisco (like all other vendors) focused on “multi-protocol” platforms.
• Because TCP/IP has emerged as the dominant protocol, our focus is entirely on IP networks.
• So, this is an Introduction to Cisco IP Network Devices
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Types of NetworksTypes of Networks
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LANsLANs
• Local-Area Networks (LANs) emerged in the mid 1980s
• LANs– connects workstations, peripherals, and
other devices in a single building– LANs made it possible to efficiently share
such things as files and printers
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Early LANs IsolatedEarly LANs Isolated
Seattle
``
`
San Francisco
New York
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Wide Area Networks (WANs)Wide Area Networks (WANs)
Seattle
San Francisco
New York
`
`
`
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LAN, CAN, MAN, and WANLAN, CAN, MAN, and WAN
• LAN - limited geographic area– office, home, small building (enterprise)
• CAN - Campus-Area Network– University, Company Tech Center (enterprise)
• MAN - Metropolitan-Area Network– citywide network, (typically involves a service provider)
• WAN - large geographic area– city-to-city, worldwide, Internet (typical involves a service
provider)
• PAN – personal area network– Cell phone, watch, PDA, bluetooth stuff (you!)
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LAN vs WANLAN vs WAN
• Early LANs and WANs typically used very different:– Protocols– Devices– Signaling– Media (physical connections, wire, RF)
Typical Early LANs Typical Early WANs
High bandwidth Low bandwidth
Cheap Costly
Intermittent, on-demand connectivityAlways “on”
Small geographical area Large geographical area
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Early LAN vs WANEarly LAN vs WAN
• Different network types, different devices:
Hub, Repeater
Bridge
LAN Switch
Router
Modem, CSU/DSU
Switch
Access Server
Router
Common LAN Devices Common WAN Devices
@ONE Spring Hands-On Institute
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Early LAN vs WANEarly LAN vs WAN
• Emerging technologies and dominance of TCP/IP spurred widespread adoption of new device types:
Switch
Multilayer Switch
Firewall
Router
Today’s LAN Devices
DSLAM
Optical Transport
Router
Today’s WAN Devices
VPN Gateway
IP Telephony (LAN/WAN)
IP Phone IP PBX
Wireless (LAN/WAN)
Bridge Access Point
@ONE Spring Hands-On Institute
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Today’s LAN/WANToday’s LAN/WAN
• Several factors have blurred the distinctions between WANs and LANs and the devices that operate in each.
• However, for the purposes of our discussions, we will talk about devices as either “LAN” or “WAN”
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The OSI Reference ModelThe OSI Reference Model
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Enter ISOEnter ISO
• ISO – International Organization for Standardization (Geneva)– Voluntary, non-treaty organization charted by the UN
• From the earliest days of networking, it was clear to ISO that standards were needed.
• Standardization aids: development, interoperability, education…
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ISO’s OSI ModelISO’s OSI Model
• ISO looked at existing network protocols (TCP/IP, XNS, SNA) and came up with OSI RM.
• OSI RM - Open Systems Interconnection Reference Model
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OSI Reference ModelOSI Reference Model
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7 - Application Layer7 - Application Layer
• Network processes to applications– Provides network services
to user applications
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6 – Presentation Layer6 – Presentation Layer
• Data Representation– Code Formatting– Negotiation of data
transfer– Ensures information sent
by the application can be transmitted on the network
– Data encryption
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5 – Session Layer5 – Session Layer
• Interhost communication– Establishes, maintains,
and manages sessions between applications
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4 – Transport Layer4 – Transport Layer
• End-to-end connections– Segmentation – Reassembly into data
stream– Offers potential of reliable
transport
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3 – Network Layer3 – Network Layer
• Addresses and best path– Logical addressing is used
at this layer• IP, AppleTalk, IPX, etc.
– Routers reside at this layer
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2 - Data-Link Layer2 - Data-Link Layer
• Access to media– Physical transmission
across the medium– Error notification, network
topology and flow control– Uses MAC (physical)
addresses– Switches and bridges
reside at this layer
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1 – Physical Layer1 – Physical Layer
• Binary Transmission– Provides the electrical,
mechanical, procedural and functional means for activating and maintaining the physical link between systems.
– The media resides at this layer
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Data Encapsulation ExampleData Encapsulation Example
End System
Intermediate Systems
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Data EncapsulationData Encapsulation
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TCP/IP vs OSI ModelTCP/IP vs OSI Model
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Cisco NetworkingCisco Networking
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Brief(est) History of LANsBrief(est) History of LANs
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Early LANsEarly LANs
• In the 1980s, several LAN technologies competed to offer Layer 1/Layer 2 services:– Token Ring (IBM)– Ethernet (Xerox, et al)– ARCnet (Datapoint)
• Later on:– FDDI, Fiber Distributed Data Interface– ATM, Asynchronous Transfer Mode
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The IEEE Working GroupsThe IEEE Working Groups
802.1
802.2
802.3
802.4
802.5
802.6
802.7
802.8
802.11
Networking Overview and Architecture
Logical Link Control
Ethernet
Token Bus
Token Ring
MANs
Broadband
Fiber Optic
Wireless Ethernet
...and more!
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TodayToday
• Ethernet is the de facto standard.
• It has crushed its competitors in the LAN space, and has been adopted for Wireless networks and Metro WANs.
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Ethernet and TCP/IPEthernet and TCP/IP
• Ethernet and TCP/IP are the most pervasive protocols
Data Link Layer
Physical Layer
Network Layer
Session Layer
Transport Layer
Presentation Layer
Application Layer
TCP/IP
Ethernet
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Device Functions at Layers Device Functions at Layers