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Network

Minggu ke – 9

Magister Teknik Elektro

Universitas Udayana

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• What is a Network?– Allows Computers to Communicate– Share Files, Printers and Other Peripherals– Connect to a Centralized Server

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• Network Communications and Protocols– Protocol - The definition of a language that allows

computers and networks to communicate

• OSI Model– Breaks network protocols down into seven different

layers.

• Computer Protocols– Languages Computers use to communicate across

networks

• Network Protocols– Languages Networks use to communicate

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Network Communications and ProtocolsComputer Protocols

• NetBEUI (NetBIOS Extended User Interface)• Microsoft Windows• File and Printer Sharing• Easiest to Setup• Works Best on Small Networks

– Less Than 25 Computers

• Large Networks Require WINS Server• Alternative is NetBIOS over TCP/IP

• IPX/SPX and NWLink (NetWare)• Allows Windows computers to communicate with Novell

based networks• Available as of Windows 95 and NT 4.0

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• TCP/IP– Most widely used protocol today– Protocol used across the Internet hence IP– Packet based– IP Based Networks

• IP Addresses• Subnet Masks• Gateway• DHCP (Dynamic Host Configuration Protocol )Server• DNS Server

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• Public IP Addresses– Given out in “Blocks”– Computers with Public IP addresses can be directly

accessed from the Internet– Poses Potential Security Risk

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• Private IP Addresses– Can not directly

connect to the Internet– Translated to public IP

address prior to sending data on the Internet

– Free for anyone to use

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• TCP/IP : IP Addresses– Dynamic vs. Static– Subnet Mask– Gateway– DNS Server

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SubnettingA Network with two levels of hierarchy (not

subnetted)

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A Network with three levels of hierarchy (subnetted)

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ARP (Address Resolution Protocol)

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• Cross Platform Communications– Linux / Unix / Mac OS X

• Samba – Allows these operating systems to use the NetBIOS Protocol to communicate with Windows operating systems

– Windows• Services for Unix (SFU) – Allows Windows

operating systems to use the NFS protocol to communicate with Linux / Unix operating systems

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• OSI Model– Breaks network protocols down into seven different

layers.• Protocol functions

• Segmentation and reassembly• Encapsulation Addressing• Connection control Multiplexing• Ordered delivery Transmission services• Flow control• Error control• synchronization

• Computer Protocols– Languages Computers use to communicate across

networks• Network Protocols

– Languages Networks use to communicate

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Layer

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Application

Presentation

Session

Transport

Network

Data Link

Physical

Users-oriented

Perspective on the OSI architecture

Point-to-point link oriented

End-to-end connection

oriented

Network service

Users of transport service

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O s

P y

E s

R t

A e

T m

I

N

G

Appli-cations

TCP

IP

Network Access protocol

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Network Protocol• Token Ring

– Backbone for large ring topologies

– Uses special packet called a Token

– Computer holding token allowed to communicate on network

• Ethernet– • Designed for LAN technologies- Bus topology; Fast Ethernet: 100

Mbps; Gigabits Ethernet: 1000 Mbps

– • Listens to network before transmission

– • Uses random wait times to resolve collisions

– • Not limited to Ring Topology

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• Ethernet implementations

10Base5: Thick Ethernet or Thicknet

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10Base2: Thin Ethernet or CheapernetIt uses bus topology with an internal transceiver or p2p connection via an external transceiver. If the station uses an internal transceiver, there is no need for an AUI cableIf the station lacks a transceiver, then an external transceiver can be used in conjunction with the AUI

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SegmentsMax. 5 segments, each segment max 185 m.Only 3 segments for connecting stations to medium; 2 segments for remote repeatersThe max.no. stations 96, 32 stations/segment

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Medium & Connectors

Descriptions

Thin coaxial cable Spec. in table

BNC-type coaxial connectors

For the end of each segment

BNC-type barrel connector

To connect 2 sections of a segment together

BNC-type terminators 50-ohm terminator

BNC-type tee connectors

To connect the medium to the external transceiver or to the NIC

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10Base-T: Twisted-Pair EthernetPhysically is star topology, logically is bus topologyThe stations are connected to a hub with either an internal or external transceiver Internal transceiver: no need AUI cableExternal transceiver: AUI cable for connecting the transceiver – interfaceMedium & connectors: twisted-pair cable and RJ-45 connectors

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Spec. 10Base-FL:Duplexity: Full-duplexPhysical topology: starMedium: Fiber 62.5/125 mMax. length: 2000 m

10Base-FL: Fiber Link EthernetStar topology, External transceiver: fiber-optic MAUAUI Cable: to connect the station – external transceiver

Medium and connectors

Medium & Connectors

Descriptions

Fiber optic cable

Graded index multimode with a 62.5 m core and 125 m cladding

ST connector Type for fiber-optic medium

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VLAN (Virtual Local Area Network)A subnetwork or a segment of a local area network configured by software, not by physical wiring

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VPN (Virtual Private Network)A network that is private, but virtualIt is private because it guarantees privacy inside the organization.It is virtual because it does not use real private WANs; the network is physically public, but virtually private

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Gigabit Media Independent Interface (GMII)(optional)

Media Access Control (MAC)full duplex and/or half duplex

1000 Base TPMA

transceiver

1000 Base – X PHY8B/10B auto-negotiation

1000 Base TPCS

Unshielded twisted pair

IEEE 802.3ab

1000 Base-LXFiber optictransceiver

1000 Base-SXFiber optictransceiver

1000 Base-CXCopper

transceiver

MultimodeFiber

ShieledCopper Cable

Single Mode orMultimode Fiber

IEEE 802.3z

Gigabit Ethernet Architecture Standard

Source - IEEE

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Gigabit Ethernet Technology

Figure 4-23.Gigabit Ethernet cabling.

1000 BASE SX fiber - short wavelength1000 BASE LX fiber - long wavelength1000 BASE CX copper - shielded twisted pair1000 BASE T copper - unshielded twisted pair* Based on Fiber Channel physical signaling technology.

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Network Hardware

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Network Hardware

• NIC – Network Interface Card• Cabling

– Cat 5– Cat 5e– Cat 6– Fiber Optic

• Hub or Repeater– Repeats information out to all ports– Creates unnecessary network traffic– Least sophisticated of all network equipment

• Switch– Analyzes packets and routes directly to destination port– More efficient than hub

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Network Hardware• Router

– More sophisticated than Switch– Knows what type of traffic– Can be used as first line of defense when securing a network

• Firewall– Not only knows type of traffic, but analyzes traffic for potential

vulnerabilities.– Rule based analysis

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• WAP – Wireless Access Point– Slower than traditional wired networks– Great for open spaces– Quickly reduces distances inside buildings– Can reach over a few miles with proper equipment– Less expensive than wired counterparts

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Internet Connection

• Types of Connections– Dial Up

• Slow• Maximum Throughput 50Kbps

– Satellite• • Available even in rural areas

• • Long response times (Latency)

• • Maximum Throughput 50Kbps up and 400Kbps down

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– DSL / Cable• • Increase speeds as needed• • Requires Phone Company or Cable Company

Support

– T1• • Maximum throughput 1,500 Kbps

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xDSL

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Network Security

• Firewalls

• Router

• VPN – Virtual Private Networking

• Wireless - WiFi– WEP – Wireless Encryption Protocol– WPA – WiFi Protected Access– Ethernet Address Lockdown

• Physical Security