dasar jaringan komputer

Chapter 3Dasar Jaringan Komputer

16 Maret 2009

Pendahuluan

Pada bab ini akan di-cover prinsip, standar dan maksud Jaringan Komputer

Termasuk didalamnya tipe dari jaringan :– Local Area Network (LAN)– Wide Area Network (WAN)– Wireless LAN (WLAN)

Apa yang kita pelajari adalah : – Network topologies, protocols, dan logical models– Kebutuhan2 hardware untuk membuat jaringan– Software untuk jaringan, metode komunikasi dan

hubungannya dengan hardware

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Pendahuluan

Internet membawa perubahan yang sangat besar pada segala bidang

Kemampuan dari ‘jaringan’ sangat menguntungkan dan membawa pengaruh yang besar pada berkembangan di segala bidang

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Support jaringan terhadap jalan hidup kita :

Meningkatkan kualitas hidup manusia dimana saja.

Pentingnya komunikasi Bagaimana cara kita berkomunikasi?

– Dengan saling berhadapan– Dengan menggunakan media?– Multimedia?

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Support jaringan terhadap jalan hidup kita :

Pada awalnya jaringan data hanya terbatas pada pertukaran informasi berdasar karakter antara komputer yang saling terhubung..

Bagaimana jaringan saat ini?

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Bagaimana pengaruh jaringan pada kehidupan se-hari2:

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In the course of a day, resources available through the Internet can help you:– Decide what to wear using online current weather

conditions.– Find the least congested route to your destination,

displaying weather and traffic video from webcams.– Check your bank balance and pay bills

electronically.– Receive and send e-mail, or make an Internet

phone call, at an Internet cafe over lunch.

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– Obtain health information and nutritional advice from experts all over the world, and post to a forum to share related health or treatment information.

– Download new recipes and cooking techniques to create a spectacular dinner.

– Post and share your photographs, home videos, and experiences with friends or with the world.

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Describe the characteristics and purpose of popular communication media such as, IM, Wikis , Blogs, Podcasting, and Collaboration Tools– Instant messaging

Real time communication between 2 or more people based on typed text

– Weblogs (Blogs) Web pages created by an individual

– FB

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– PodcastingWebsite that contains audio files

available for downloading– Wiki

Wikis are web pages that groups of people can edit and view together.

Whereas a blog is more of an individual, personal journal, a wiki is a group creation.

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– PodcastingWebsite that contains audio files

available for downloading– Wiki

Wikis are web pages that groups of people can edit and view together.

Whereas a blog is more of an individual, personal journal, a wiki is a group creation.

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Examples of Today’s Popular Communication Tools

Weblogs (blogs)– Weblogs (Blogs) are web pages that are

easy to update and edit.– Blogs give anyone a means to

communicate their thoughts to a global audience without technical knowledge of web design.

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Collaboration Tools– Collaboration tools give people the opportunity to

work together on shared documents. – Without the constraints of location or time zone,

individuals connected to a shared system can speak to each other, share text and graphics, and edit documents together

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Explain ways that using information networks to share and collaborate improves teaching and learning

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Network supporting the way we learn

Traditional learning : – Text book– Instructor

Online courses can contain voice, data, and video, and are available to the students at any time from any place

Blended courses can combine instructor-led classes with online courseware to provide the best of both delivery methods.

E-Learning Online distance learning

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Network supporting the way we learn

Online courseware and delivery offer many benefits to businesses. – Current and accurate training materials.– Availability of training to a wide audience.– Consistent quality of instruction. – Cost reduction.

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Intranets, private networks in use by just one company, enable businesses to communicate and perform transactions among global employee and branch locations.

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Describe ways communication over a network changes the way we work

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Describe ways communication over a network supports the way we play

Networks are systems that are formed by links. People use different types of networks every day:

– Mail delivery system– Telephone system– Public transportation system– Corporate computer network– The Internet

Computers can be linked by networks to share data and resources.

A network can be as simple as two computers connected by a single cable or as complex as hundreds of computers connected to devices that control the flow of information.

Principles of Networking

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Networking Fundamentals

Computer network:– Two or more computers connected together

Each is a Node

Benefits of a network:– Sharing resources– Transferring files

Computer Networks

Network devices include:– Desktop and laptop computers– Printers and scanners– PDAs and Smartphones– File and print servers

Resources shared across networks include:– Services, such as printing or scanning– Storage devices, such as hard drives or optical drives– Applications, such as databases

Different types of network media:– Copper cabling – Fiber-optic cabling– Wireless connection

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Network Architecture

Network designs:– Individual PC controlled:

Peer-to-peer (P2P)

– Centrally controlled: Client/server

Peer-to-peer

Client/server

Benefits of Networking

Fewer peripherals needed

Increased communication capabilities

Avoid file duplication and corruption

Lower cost licensing Centralized

administration Conserve resources

Types of Networks

A computer network is identified by: The type of media used to connect the devices The type of networking

devices used How the resources are

managed How the network is

organized How the data is stored The area it serves

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LANs and WANs

Local area network (LAN):– Nodes are within a small geographic region:

Homes Schools Small businesses

Wide area network (WAN):– LANs connected over long distances:

A few miles to thousands of miles Use telecommunications lines

Local Area Network (LAN)

A group of interconnected computers that is under the same administrative control.

Can be as small as a single local network installed in a home or small office.

Can consist of interconnected local networks consisting of many hundreds of hosts, installed in multiple buildings and locations.

Wide Area Network (WAN)

A WAN connects LANs in geographically separated locations.

A WAN covers a much larger area than a LAN.

The Internet is a large WAN. Telecommunications service

providers (TSP) are used to interconnect these LANs at different locations.

Wireless LAN (WLAN)

Wireless devices are used to transmit and receive data using radio waves.

Wireless devices connect to access points within a specified area.

Access points connect to the network using copper cabling.

WLAN coverage can be limited to the area of a room, or can have greater range.

You can share resources such as files and printers, and access the Internet on a WLAN.

Peer-to-Peer Networking

Share files, send messages, and print to a shared printer.

Each computer has similar capabilities and responsibilities.

Each user decides which data and devices to share. No central point of control in the network. Best if there are ten or fewer computers.

Disadvantages of Peer-to-Peer

Without centralized network administration, it is difficult to determine who controls network resources.

Without centralized security, each computer must use separate security measures for data protection.

More complex and difficult to manage as the number of computers on the network increases.

Without centralized data storage, data backups must be performed by users.

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Peer-to-Peer Networks

Nodes communicate with each other:– Peers

Share peripheral devices:– Printers– Scanners

Home and small office networks

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Types of Peer-to-Peer Networks

Power line Phone line Ethernet Wireless

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Ethernet Networks

Ethernet network adapters are used to connect nodes

– NIC card– PC Card– USB adapter

Computers are connected to each other using unshielded twisted pair cable

RJ-45

Phoneline

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Ethernet Switches

Keep track of data packets Amplify and retransmit signals Keep the network running efficiently

39

Ethernet Routers

Transfer packets from one network to another Home Internet routers transfer data from the Internet

to the home network. Router

40

Wireless Networks

• Use radio waves to connect nodes• Basically an Ethernet network that uses radio waves instead

of wires• Each node requires a wireless network adapter:

– Transceiver

41

Power Line Networks

Computers are connected to a house’s electrical wiring to create a network

Power line network adapter is used to connect nodes to electrical outlets

42

Phone Line Networks

Computers are connected to a house’s telephone wiring to create a network

Home phone line network adapter is used to connect nodes to phone jacks

Client/Server Network

Client/server network model provides security and control for the network.

Client requests information or services from the server. Server provides the requested information or service. Servers are maintained by network administrators.

– Data backups and security measures– Control of user access to network resources

Centralized storage and services include:– Data stored on a centralized file server– Shared printers managed by a print server– Users have proper permissions to access data or printers

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Client/Server Networks

Client computers:– Users

Server computers:– Provide resources to clients– Central network control

Internet– A large, multi-server,

multi-client network.

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Network Components

• Transmission media• Network adapters• Navigation devices• Network software

46

Transmission Media

Provides communications channel between nodes

Forms of media:– Telephone wire:

Twisted pair– Coaxial cable– Fiber-optic cable– Radio waves:

Wireless Bandwidth:

– Data transfer rate– Throughput

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Network Adapters

Devices connected to or installed in nodes:– Network interface cards (NIC)– External network adapter

Enable communication between nodes

48

Network Navigation Devices

• Devices that help make data flow possible

• Routers:– Route data between networks

• Switches:– Receive data and retransmit it to

nodes on the network

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Networking Software

Peer-to-peer Software: Built into operating systems that support networking

– Windows– Mac OS

Client/server Software Network operating system (NOS) software

– Windows XP Professional– Windows Server 2003– Novell Netware

Bandwidth

Amount of data that can be transmitted within a fixed time period

Measured in bits per second and is usually denoted by the following:

- bps - bits per second

- Kbps - kilobits per second

- Mbps - megabits per second

Three Modes of Transmission

Data is transmitted in one of three modes:

1. Simplex (Unidirectional transmission) is a single, one-way transmission.

– Example: The signal sent from a TV station to your TV.

2. Half-duplex allows data to flow in one direction at a time.

– Simultaneous transmission in two directions is not allowed.

– Example: Two-way radios, police or emergency mobile radios

3. Full-duplex allows data to flow in both directions at the same time.

– Bandwidth is measured in only one direction. 100 Mbps full-duplex means a bandwidth of 100 Mbps in each direction.

– Broadband technologies, such as digital subscriber line (DSL) and cable, operate in full-duplex mode.

IP Address

An IP address is a unique number that is used to identify a network device.

An IP address is represented as a 32-bit binary number, divided into four octets (groups of eight bits):

– Example: 10111110.01100100.00000101.00110110 An IP address is also represented in a dotted decimal format.

– Example: 190.100.5.54 When a host is configured with an IP address, it is entered as a

dotted decimal number, such as 192.168.1.5. Unique IP addresses on a network ensure that data can be sent

to and received from the correct network device.

IP Address Classes

Class A– Large networks, implemented by large companies and

some countries Class B

– Medium-sized networks, implemented by universities Class C

– Small networks, implemented by ISP for customer subscriptions

Class D– Special use for multicasting

Class E– Used for experimental testing

Subnet Masks

Used to indicate the network portion of an IP address

Is a dotted decimal number

Usually, all hosts within a broadcast domain of a LAN (bounded by routers) use the same subnet mask.

The default subnet masks for three classes of IP addresses:

– 255.0.0.0 is the subnet mask for Class A

– 255.255.0.0 is the subnet mask for Class B

– 255.255.255.0 is the subnet mask for Class C If an organization owns one Class B network but needs to provide IP

addresses for four LANs, the organization will subdivide the Class B network into four smaller parts by using subnetting, which is a logical division of a network. The subnet mask specifies how it is subdivided.

IP SubnettingIP Subnetting

SubnetSubnet

Perlunya membagi network menjadi subnetwork: Mengurangi kepadatan jaringan

– Router diperlukan untuk menghubungkan antar subnet– Router membatasi broadcast traffic– Lebih efisien

Menyesuaikan dengan tata letak fisik– Mis.: 1 subnet per lantai pada bangunan

Fungsi Administratif– Mis.: Bagian Keuangan pada 1 subnet dan Bagian R&D

pada subnet lainnya. Untuk mengantisipasi pertumbuhan yang akan datang

Caranya?

NetworkNetwork HostHost

32 bit

SubnetSubnet

NetworkNetwork HostHost

Meminjam sebagian bit dari Host ID

Subnet MaskSubnet Mask

Network AddressNetwork Address Host AddressHost Address

32 bit

Subnet Mask adalah suatu cara untuk mengekstraksi Network Address dari sebuah IP Address.

172.16 12.1

00001100.0000000110101100. 00010000

IP Address

00000000.0000000011111111.11111111AND

00000000.0000000010101100. 00010000

172.16 0.0

IP Address

IP Address

Subnet Mask

Network Addr.

Network Addr.

Subnet MaskSubnet MaskFormat Subnet mask :

semua bit yang merepresentasikan Network Address adalah 1 semua bit yang merepresentasikan Host Address adalah 0. Umumnya

Subnet Mask dinyatakan dalam bentuk dotted decimal.

Class A

Class B

Class C

1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0

Subnet Mask untuk Classful IP Address

255255

255255

255255

00

255255

255255

00

00

255255

00

00

00

Contoh Subnet MaskContoh Subnet Mask

IP : 152 .118 .98 .4

Subnet Mask : 255 .255 .255 .0

AND

Network Add. : 152 .118 .98 .0

Fungsi Subnet MaskFungsi Subnet MaskSubnet Mask digunakan untuk menentukan Network Address dari sebuah IP

Address. Network Address ini kemudian dicocokkan dengan Routing Table untuk menentukan jalur transit data

Ekivalen Desimal dari pola bit untuk subnet maskEkivalen Desimal dari pola bit untuk subnet mask

Subnet Mask - SubnetSubnet Mask - SubnetMisalnya:

• Sebuah Network Address Class B: 152.118.0.0/255.255.0.0

• Dipinjam 8 bit dari Host ID sebagai Subnet

• Maka Subnet Mask Menjadi:

255 .255 .11111111 .0 = 255.255.255.0

8 bit untuk subnet

Anggota SubnetAnggota Subnet• Dengan demikian Network Address Class B: 152.118.0.0 dengan

menggunakan SNM 255.255.255.0 akan memiliki 28 = 256 subnet sbb:

Subnet No. Subnet Address Host Range

0152.118. 00000000 .0

152.118.0.0152.118.0.1 - 152.118.0.254

B-cast Address

152.118.0. 11111111152.118.0.255

1152.118. 00000001 .0

152.118.1.0152.118.1.1 - 152.118.1.254

152.118.1. 11111111152.118.1.255

2152.118. 00000010 .0

152.118.2.0152.118.2.1 - 152.118.2.254

152.118.2. 11111111152.118.2.255

3152.118. 00000011 .0

152.118.3.0152.118.3.1 - 152.118.3.254

152.118.3. 11111111152.118.3.255

4152.118. 00000100 .0

152.118.4.0152.118.4.1 - 152.118.4.254

152.118.4. 11111111152.118.4.255

... ... ... ...

255152.118. 11111111 .0

152.118.255.0152.118.255.1 - 152.118.255.254

152.118.255. 11111111152.118.255.255

U N U S A B L EU N U S A B L E


Subnet Mask - SubnetSubnet Mask - SubnetMisalnya:

• Sebuah Network Address Class C: 205.12.3.0/255.255.255.0

• Dipinjam 2 bit dari Host ID sebagai Subnet

• Maka Subnet Mask Menjadi:

255 .255 .255 .1100 0000 = 255.255.255.192

2 bit untuk subnet

Anggota SubnetAnggota Subnet• Dengan demikian Network Address Class C: 205.12.3.0 dengan

menggunakan SNM 255.255.255.192 akan memiliki 22 = 4 subnet sbb:

B-cast Address

205.12.3. 00111111205.12.3.63

205.12.3. 01111111205.12.3.127

205.12.3. 10111111205.12.3.191

Subnet Address

205.12. 3. 00000000205.12.3.0

205.12. 3. 01000000 205.12.3.64

205.12.3. 10000000205.12.3.128

205.12.3. 11000000205.12.3.192

Host Range

205.12.3.00000001 - 205.12.3.00111110205.12.3.1 - 205.12.3.62

205.12.3.01000001 - 205.12.3.01111110205.12.3.65 - 205.12.3.127

205.12.3. 10000001 - 205.12.3. 10111110205.12.3.129 - 205.12.3.190

205.12.3. 11000001 - 205.12.3. 11111110205.12.3.193 - 205.12.3.254

SN No.

0

1

2

3205.12.3. 11111111

205.12.3.255



Efisiensi Penggunaan IP pada SubnetEfisiensi Penggunaan IP pada SubnetContoh: Penggunaan IP untuk subnet Class C (Max Host= 254)

LatihanLatihan

Lakukan subnet untuk sebuah IP Class B : 148.10.0.0 sehingga satu subnet memiliki 4096 host.

– Berapa bit subnet yang dipinjam dari host?– Berapakah Subnet Masknya?– Berapakah Network IP Address untuk subnet ke -7 ?– IP Address 148.10.5.10 merupakan anggota dari Network IP

Address berapa?

(Pakai calculator biasa dulu!) Gunakan IP Subnet Calculator untuk menguji hasil

anda!

IP Address Configuration

Manual configuration

– Manually configure each device with the proper IP address and subnet mask.

Dynamic configuration

– A Dynamic Host Configuration Protocol (DHCP) server automatically assigns IP addresses to network hosts.

Network Interface Card (NIC) is the hardware that enables a computer to connect to a network and it has two addresses:

– The IP address is a logical address that can be changed.

– The Media Access Control (MAC) address is "burned-in" or permanently programmed into the NIC when manufactured. The MAC address cannot be changed.

Dynamic Host Configuration Protocol (DHCP)

DHCP automatically provides computers with an IP address.

The DHCP server can assign these to hosts:– IP address– Subnet mask– Default gateway– Domain Name System

(DNS) server address

DHCP Process and Advantages

DHCP process:1. DHCP server receives a request from a host.

2. Server selects IP address information from a database.

3. Server offers the addresses to requesting host.

4. If the host accepts the offer, the server leases the IP address for a specific period of time.

Advantages of DHCP: Simplifies the administration of a network Reduces the possibility of assigning duplicate or invalid

addresses

Configure Host to Use DHCP

Configure the host to "Obtain an IP address automatically" in the TCP/IP properties of the NIC configuration window

Internet Protocols

A protocol is a set of rules.

Internet protocols are sets of rules governing communication within and between computers on a network.

Many protocols consist of a suite (or group) of protocols stacked in layers. These layers depend on the operation of the other layers in the suite to function properly.

The main functions of protocols:

– Identifying errors

– Compressing the data

– Deciding how data is to be sent

– Addressing data

– Deciding how to announce sent and received data

Common Network Protocols Protocols used for browsing the web, sending and

receiving e-mail, and transferring data files

DescriptionTCP/IP A protocol used to transport data on the Internet.

NETBEUI NETBIOS

A small, fast protocol designed for a workgroup network that requires no connection to the Internet.

IPX and SPX

A protocol used to transport data on a Novell Netware network.

HTTP and HTTPS

A protocol that defines how files are exchanged on the Web.

FTP A protocol that provides services for file transfer and manipulation.

SSH A protocol that is used to connect computers together securely.

Telnet A protocol that uses a text-based connection to a remote computer.

POP A protocol used to download email messages from an email server.

IMAP A protocol used to download email messages from an email server.

SMTP A protocol used to send mail in a TCP/IP network.

Internet Control Message Protocol (ICMP)

Internet Control Message Protocol (ICMP) is used by devices on a network to send control and error messages to computers and servers.

PING (Packet Internet Groper) is a simple command line utility used to test connections between computers

– Used to determine whether a specific IP address is accessible.– Used with either the hostname or the IP address.– Works by sending an ICMP echo request to a destination

computer.– Receiving device sends back an ICMP echo reply message.

Ping Command Switches

These command line switches (options) can be used with the ping command.

Output of the Ping Command

Four ICMP echo requests (pings) are sent to the destination computer to determine the reliability and reachability of the destination computer.

Physical Network Components

Network devices:– Computers– Hubs– Switches– Routers– Wireless access points

Network media:– Twisted-pair copper cabling– Fiber-optic cabling– Radio waves

Repeaters, Hubs, Bridges, Switches, Routers and Gateways

(a) Which device is in which layer.

(b) Frames, packets, and headers.

Repeaters, Hubs, Bridges, Switches, Routers and Gateways (2)

(a) A hub. (b) A bridge. (c) a switch.

Virtual LANsA building with centralized wiring using hubs and a

switch.

Virtual LANs (2)

(a) Four physical LANs organized into two VLANs,

gray and white, by two bridges.

(b) The same 15 machines organized into two

VLANs by switches.

Hubs

Extend the range of a signal by receiving then regenerating it and sending it out all other ports

Traffic is sent out all ports of the hub Allow a lot of collisions on the network segment and are

often not a good solution Also called concentrators because they serve as a

central connection point for a LAN

Bridges and Switches

A packet, along with its MAC address information, is called a frame.

LANs are often divided into sections called segments bounded by bridges.

A bridge has the intelligence to determine if an incoming frame is to be sent to a different segment, or dropped. A bridge has two ports.

A switch (multiport bridge) has several ports and refers to a table of MAC addresses to determine which port to use to forward the frame.

Routers

Routers are devices that connect entire networks to each other.

– Use IP addresses to forward packets to other networks.– Can be a computer with special network software installed.– Can be a device built by network equipment manufacturers.– Contain tables of IP addresses along with optimal routes to

other networks.

Wireless Access Points

Provide network access to wireless devices such as laptops and PDAs.

Use radio waves to communicate with radios in computers, PDAs, and other wireless access points.

Have limited range of coverage.

Multipurpose Devices

Perform more than one function.

More convenient to purchase and configure just one device.

Combines the functions of a switch, a router and a wireless access point into one device.

The Linksys 300N is an example of a multipurpose device.

Twisted-Pair Cabling

A pair of twisted wires forms a circuit that transmits data.

The twisted wires provide protection against crosstalk (electrical noise) because of the cancellation effect.

Pairs of copper wires are encased in color-coded plastic insulation and twisted together.

An outer jacket, called poly-vinyl chloride (PVC), protects the bundles of twisted pairs.

Two Basic Types of Twisted-Pair Cables

Unshielded twisted-pair (UTP)

– Has two or four pairs of wires– Relies on the cancellation effect for reduction of interference

caused by electromagnetic interface (EMI) and radio frequency interference (RFI)

– Most commonly used cabling in networks– Has a range of 328 ft (100 meters)

Shielded twisted-pair (STP)

– Each pair is wrapped in metallic foil to better shield the wires from electrical noise and then the four pairs of wires are then wrapped in an overall metallic braid or foil.

– Reduces electrical noise from within the cable. – Reduces EMI and RFI from outside the cable.

Category Rating

UTP comes in several categories that are based on two factors:– The number of wires in the cable– The number of twists in those wires

Category 3 is used for telephone connections. Category 5 and Category 5e have are the most

common network cables used. Category 6 cable has higher data rate than the

Cat 5 cables.

Coaxial Cable

A copper-cored network cable surrounded by a heavy shielding

Types of coaxial cable:

– Thicknet or 10Base5 - Coax cable that was used in networks and operated at 10 megabits per second with a maximum length of 500 m

– Thinnet or 10Base2 - Coax cable that was used in networks and operated at 10 megabits per second with a maximum length of 185 m

– RG-59 - Most commonly used for cable television in the US

– RG-6 - Higher quality cable than RG-59 with more bandwidth and less susceptibility to interference

Fiber-Optic Cable

A glass or plastic strand that transmits information using light and is made up of one or more optical fibers enclosed together in a sheath or jacket.

Not affected by electromagnetic or radio frequency interference.

Signals are clearer, can go farther, and have greater bandwidth than with copper cable.

Usually more expensive than copper cabling and the connectors are more costly and harder to assemble.

Two types of glass fiber-optic cable:

– Multimode and Single-mode

Two Types of LAN Topologies

Physical topology is the physical layout of the components on the network

Logical topology determines how the hosts access the medium to communicate across the network

LAN Physical Topologies

A physical topology defines the way in which computers, printers, and other devices are connected to a network.

Bus Ring Star Hierarchical star Mesh

Bus Topology

Each computer connects to a common cable

Cable connects one computer to the next

Ends of the cable have a terminator installed to prevent signal reflections and network errors

Only one computer can transmit data at a time or frames will collide and be destroyed

Bus topology is rarely used today. Possibly suitable for a home office or small business with few hosts

Ring Topology

Hosts are connected in a physical ring or circle. The ring has no beginning or end, so the cable

does not need to be terminated. A special frame, a token, travels

around the ring, stopping at each host.

The advantage of a ring topology is that there are no collisions.

There are two types of ring topologies:– Single-ring and Dual-ring

Star Topology

Has a central connection point: a hub, switch, or router

Hosts connect directly to the central point with a cable

Costs more to implement than the bus topology because more cable is used, and a central device is needed

Easy to troubleshoot, since each host is connected to the central device with its own wire.

Hierarchical or Extended Star Topology

A star network with an additional networking device connected to the main networking device to increase the size of the network.

Used for larger networks

Mesh Topology

Connects all devices to each other Failure of any cable will not affect the network Used in WANs that interconnect LANs Expensive and difficult to install

because of the amount of cable needed

The Internet is an example of a mesh topology

Often used by governments when data must be available in the event of a partial network failure

Logical Topologies

The two most common types of logical topologies are broadcast and token passing.

In a broadcast topology, there is no order that the hosts must follow to use the network – it is first come, first served for transmitting data on the network.

Token passing controls network access by passing an electronic token sequentially to each host. When a host receives the token, it can send data on the network. If the host has no data to send, it passes the token to the next host and the process repeats itself.

LAN Architecture

Is the overall structure of a computer or communication system.

Designed for a specific use and have different speeds and capabilities.

Describes both the physical and logical topologies used in a network.

The three most common LAN architectures:– Ethernet– Token Ring– Fiber-Distributed

Data Interface (FDDI)

Ethernet

Based on the IEEE 802.3 standard, which specifies that a network use the Carrier Sense Multiple Access with the Collision Detection (CSMA/CD) access control method.

– Hosts access the network using the first come, first served broadcast topology method to transmit data.

Standard transfer rates – 10 Mbps (Ethernet) “10Base-T”

– 100 Mbps (FastEthernet) “100Base-T”

– 1000 Mbps = 1 Gbps (Gigabit Ethernet) “1000Base-T”

Token Ring

Reliable network architecture Originally developed by IBM Based on the token-passing

access control method Often integrated with IBM

mainframe systems Used with smaller computers and mainframes Physically, a star-wired ring because the outer appearance

of the network design is a star Inside the device, wiring forms a circular data path, creating

a logical ring

Fiber Distributed Data Interface (FDDI)

A type of Token Ring network Often used for LANs, connecting several buildings in an

office complex or on a university campus Runs on fiber-optic cable High-speed performance combined with token-passing

advantage Runs at 100 Mbps with a primary and secondary ring

topology Normally, traffic flows only on the primary ring and uses

a secondary ring is a backup. FDDI dual ring supports up to 500 computers per ring

Standards OrganizationsName Type Standards Established

ITU-TITU Telecommunication Standardization Sector

(formerly CCITT)

one of the three Sectors of the International

Telecommunication Union

Standards covering all fields of

telecommunications

Became ITU-T in 1992

IEEE Institute of Electrical and Electronics Engineers

A non-profit, technical professional association

Standards for the computer and electronics

industry1884

ISOInternational

Organization for Standardization

A network of the national standards institutes of 157

countries

Promote the development of international standards

agreements1947

IAB Internet Architecture Board

A committee; an advisory body

Oversees the technical and engineering

development of the Internet

1979; first named ICCB

IECInternational

Electrotechnical Commission

Global organizationStandards for all

electrical, electronic, and related technologies

1906

ANSI American National Standards Institute

Private, non-profit organization

Seeks to establish consensus among groups

1918

TIA/EIA

Telecommunications Industry Association / Electronic Industries

Alliance

Trade associationsStandards for voice and

data wiring for LANs

After the deregulation of the

U.S. telephone industry in 1984

Ethernet Standards

Ethernet protocols describe the rules that control how communication occurs on an Ethernet network.

The 802.2 standard defines how a device addresses other devices on the medium.

The 802.3 standard defines the methodology that devices must use when they use the media.

The 802.11x standards define how wireless devices communicate using radio waves.

Cabled Ethernet Standards

IEEE 802.3 Ethernet standard specifies that a network implement the CSMA/CD access control method.

In CSMA/CD operation:

– All end stations "listen" to the network wire for clearance to send data.

– When the end station detects that no other host is transmitting, the end station will attempt to send data.

– If no other station sends any data at the same time, this transmission will arrive at the destination computer successfully.

– If another end station transmits at the same time, a collision will occur on the network media.

– The first station that detects the collision, sends out a jam signal to tell all stations to stop transmitting and to run a backoff algorithm.

– All stations stop transmitting and re-try after a random period of time.

10BASE-T

10BASE-T is an Ethernet technology that uses a star topology.

– The ten (10) represents a speed of 10 Mbps.– BASE represents baseband transmission.– The T represents twisted-pair cabling.

Advantages of 10BASE-T:

– Installation is inexpensive compared to fiber-optic installation.– Cables are thin, flexible, and easier to install than coaxial

cabling.– Equipment and cables are easy to upgrade.

Disadvantages of 10BASE-T:

– The maximum length for a 10BASE-T segment is 328 ft (100 m).

– Cables are susceptible to Electromagnetic Interference (EMI).

100BASE-TX “FastEthernet”

Has a theoretical bandwidth of 100 Mbps. The "X" indicates different types of copper and fiber-optic can be

used. Advantages of 100BASE-TX:

– Transfer rates of 100BASE-TX are ten times that of 10BASE-T– 100BASE-X uses twisted-pair, inexpensive and easy to install

Disadvantages of 100BASE-TX:– Maximum length for a 100BASE-TX segment is 329 ft (100 m).– Cables are susceptible to Electromagnetic Interference (EMI).

1000BASE-TX “Gigabit Ethernet”

Advantages of 1000BASE-T:– 1 Gbps is ten times faster than Fast Ethernet and 100 times

faster than Ethernet.– Increased speed makes it possible to implement bandwidth-

intensive applications, such as live video.– The 1000BASE-T architecture has interoperability with

10BASE-T and 100BASE-TX. Disadvantages of 1000BASE-T:

– Maximum length for a 1000BASE-T segment is 328 ft (100 m).– It is susceptible to interference.– Gigabit NICs and Switches are expensive.– Additional equipment is required.

Wireless Ethernet Standards

IEEE 802.11 is the standard that specifies connectivity for wireless networks.

Wi-Fi (wireless fidelity), refers to the 802.11 family– 802.11 (the original specification)– 802.11b– 802.11a– 802.11g– 802.11n– These protocols specify the frequencies, speeds, and other

capabilities of the different Wi-Fi standards.

Wireless Ethernet StandardsBandwidth Frequency Range Interoperability

802.11a Up to 54 Mbps 5 GHz band100 feet

(30 meters)

Not interoperable with 802.11b, 802.11g, or

802.11n

802.11b Up to 11 Mbps 2.4 GHz band100 feet

(30 meters)Interoperable with

802.11g

802.11g Up to 54 Mbps 2.4 GHz band100 feet

(30 meters)Interoperable with

802.11b

802.11n

(Pre-standard)Up to 540 Mbps 2.4 GHz band

164 feet (50 meters)

Interoperable with 802.11b and 802.11g

802.15.1 Bluetooth

Up to 2 Mbps2.4 GHz band

or 5 GHz band

30 feet (10 meters)

Not interoperable with any other 802.11

OSI and TCP/IP Data Models

Architectural model– Separates functions of protocols into manageable layers– Each layer performs a specific function in network

communication TCP/IP model

– A four-layer model that explains the TCP/IP suite of protocols– TCP/IP is the dominant standard for transporting data across

networks Open Systems Interconnect (OSI) model

– Standards defining how devices communicate on a network– Ensures interoperability between network devices

The TCP/IP Reference Model

Description Protocols

Application Provides network services to user applications

HTTP, HTML, Telnet, FTP, SMTP,

DNS

Transport Provides end-to-end management of data and divides data into segments

TCP, UDP

Internet Provides connectivity between hosts in the network

IP, ICMP, RIP, ARP

Network Access

Describes the standards that hosts use to access the physical media

Frame of reference used to develop the Internet's protocols Consists of layers that perform functions necessary to prepare data

for transmission over a network

The OSI Model

The OSI model is an industry standard framework that is used to divide network communications into seven layers.

Although other models exist, most network vendors today build their products using this framework.

A protocol stack is a system that implements protocol behavior using a series of layers.

– Protocol stacks can be implemented either in hardware or software, or in a combination of both.

– Typically, only the lower layers are implemented in hardware, and the higher layers are implemented in software.

The OSI ModelLayer Description

Application 7 Responsible for network services to applications

Presentation 6 Transforms data formats to provide a standard interface for the Application layer

Session 5 Establishes, manages and terminates the connections between the local and remote application

Transport 4 Provides reliable transport and flow control across a network

Network 3 Responsible for logical addressing and the domain of routing

Data Link 2 Provides physical addressing and media access procedures

Physical 1 Defines all the electrical and physical specifications for devices

Remember the OSI layers with this mnemonic:

"Please Do Not Throw Sausage Pizza Away"

Compare OSI and TCP/IP Models

Power Line Communication (PLC)

Uses power distribution wires (local electric grid) to send and receive data.

May be available in areas without any other service. Is faster than an analog modem. May cost less than other high-speed connections. Will become more common in time. Can be used in a home or office environment through an

electrical outlet. Can control lighting and appliances.

Power Line Communication (PLC)

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