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Básico de Internetworking
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Agenda
História do Networking 
Como construir uma LAN
Topologia das LANs
Equipamentos LAN/WAN
História do Networking
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Redes Primitivas
Samuel Morse
Alexander Graham Bell
Emile Baudot
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Redes Telefônicas
Rede Analógica
Telefone segundo Bell
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Desenvolvimento Importante
1966—Carterphone acoplado às linhas telefônicas permitia a transmissão chamadas via rádio para os trabalhadores da construção.
1975—FCC regulamenta que se poderia acoplar equipamentos às linhas telefônicas , desde que seguissem algumas especificações.
1977—FCC Parte 68 foi responsável pelas definições das especificações técnicas.
1984—Foi definido que as empresas Bell System/AT&T deveriam ser divididas.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Rede Telefônica
Bell Atlantic
MCI
AT&T
Pacific Bell
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
1960s–1970s Comunicação
IBM Host Computer Systems Network Architecture (SNA)
Programas de Aplicação
Banco de Dados
Impressão
Linhas de acesso de baixa velocidade
Rede Digital
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Problema...
Analógico
Digital
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Sinais Analógicos e Digitais
Transmissão Digital 
1’s e 0’s
On ou Off
Computer-speak
1
0
1
0 0 1 1 0 1
“1” bit
“0” bit
Start
Bit
Stop
Bit
Transmissão Analógica 
Com ou sem fio, 
Sinais de Áudio
Informações codificadas através
de amplitude de sinais, freqüência, e fase
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Solução —Modems
Modem—Modulator/Demodulator
Traduz os sinais digitais dos computadores em sinais analógicos que o mundo da telefonia pode entender e vice versa.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Solução — Modems
Modem—Modulator/Demodulator
Traduz os sinais digitais dos computadores em sinais analógicos que o mundo da telefonia pode entender e vice versa.
Modem
Modem
POTS (Plain Old Telephone Service)
Mainframe
Host 
POTS
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Outra Solução — Multiplexação
Baseband— Carrega apenas 1 sinal por vez
Broadband—Capaz de carregar
 múltiplos sinais simultaneamente.
Multiplexer—Agrega vários sinais sobre um único meio físico. 
Mainframe
Host 
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Broadband— 
Wide-Area Network 
(WAN)
Baseband— 
Local-Area Network
(LAN)
Baseband versus Broadband
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
1960s–1970s Comunicação
Digital
Digital
Mainframe
Host 
Escritório Remoto
Matriz
POTS
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
1960s–1970s Communications
Conexão
Dialup Modem
Escritório 
de vendas
Digital
Mainframe
Host 
Matriz
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Aniversário do PC ( Personal Computer )
Aplicações
Arquivo de documentos
Poder de processamento
Opções de Impressão
Terminais Inteligentes
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
A Internet—1970s e 1980s
ARPANET—Advanced Research Projects Agency Network, Dept. of Defense
Desenvolvido em meados dos anos 60
Fundação de pesquisa para Universidades e Empresas. 
A primeira rede comutada de pacotes foi construída pela BBN—Dez 1969
Muitas LANs foram conectadas ao ARPANET com o TCP/IP
Foi desativada em 1990 dando lugar à uma nova rede que estava surgindo.
NSFNET—National Science Foundation, Final dos anos 70.
Sucessor de alta velocidade do ARPANET 
6 super computadores : San Diego, Boulder, Champaign, Pittsburgh, Ithaca, and Princeton
Cada Super computadores tinha um microcomputador ligado a ele que falava TCP/IP
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
A Internet 
ANSNET (Advanced Networks and Services)
Assumiu a NFSNET em 1990
Formada por MCI, MERIT, e IBM para uso comercial
Evoluiu para links de 1.5-Mbps para 45 Mbps, e vendida para a AOL em 1995
NFS fechou contrato com os 4 maiores Provedores de Acesso dos USA.
Pacific Bell (San Francisco), Ameritech (Chicago), MFS (Washington, D.C.), Sprint (New York City).
Além de alguns Backbones do Governo.
Em meados dos anos 80, várias redes se viram como “A Internet”
TCP/IP é a cola que segurou todas juntas.
Em Janeiro de 1992, “Internet Society” deu forma às primeiras aplicações:
E-mail, noticias, acesso remoto, transferencia de arquivo, WWW
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Anos 90—Rede Global
1992—Montado o primeiro backbone, 3,000 redes, 200K computadores.
1995—Multiplos backbones, centenas de redes regionais, dezenas de
 milhares de redes, hosts e usuários.
 Dobrando cada ano!
Como uma LAN é construída
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Local-Area Network—LAN
O que é uma LAN? 
Uma coleção de computadores, impressoras, modems, e outros equipamentos que podem se comunicar entre si em uma pequena área. (< ~ 3000 m )
O que são os componentes ?
Computadores, sistemas operacionais , placas de rede (NIC), e concentradores.
Como a LAN é controlada?
Protocolos—São descrições formais de regras/convenções de como os dispositivos da rede irão trocar informações.
Padrões—Ajusta as regras e procedimentos que são especificados oficialmente. 
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Local-Area Networks
LANs são projetadas para:
Opere dentro de uma área geográfica limitada
Permita múltiplos acessos em alta velocidade
Controle a rede confidencialmente sob a administração local
Forneça acesso completo à todos os serviços
Conecte dispositivos fisicamente adjacentes
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Sistemas Operacionais
Software que permite se comunicar e compartilhar recursos de dados e da rede
Examples:
AppleTalk
NetWare
Banyan VINES
PC ou Workstation
sem Sistema Operacional
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Porta RJ45 ou BNC
Network Interface 
Card (NIC)
Network Interface Card - NIC
Amplifica os sinais Eletrônicos 
Faz empacotamento para transmissão
Faz a conexão física do PC com a Rede
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Impressora
(Também com placa de rede)
PC or Workstation
Hub - Concentrador
É utilizado como concentrador da rede
Contém múltiplas portas, onde são conectados os equipamentos da rede. 
Hub
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Impressora
NIC
PC or Workstation
Hub
Cabos ou Meios de transmissão
Ambientes físicos 
Par Trançado
Cabo Coaxial
Conectores (RJ-11, RJ-45, etc.)
Cabos
Fibra Óptica
WireLess
Conectores
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Cabeamento de Rede
Meios de conexão dos componentes da rede
NIC - Faz interfacecom o meio físico.
O cabo de Lan carrega apenas 1 sinal por vez
Os cabos de Wan carregam múltiplos sinais.
Tipos de cabeamento 
Par Trançado
Cabo coaxial
Fibra óptica
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Par Trançado (UTP e STP)
Velocidade de transmissão: 10/100/1000 Mbps 
Custo Relativo : 	 Baixo
Tamanho do conector:	 Pequeno
Comprimento máximo do cabo: 	100 m 
Código de Cores
Isolação Plástica
Par trançado
Revestimento
 Exterior
STP : 
Com isolação
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Par Trançado (UTP e STP)
Par Metálico Trançado:
Dois fios metálicos enrolados em espiral  propriedades elétricas constantes ao longo do suporte;
Suporte tradicional nos sistemas telefônicos  grande disponibilidade
Tipo blindado (STP) e sem blindagem (UTP):
Cabos STP (“Shielded Twisted Pairs”):
Classificação pela IBM
2 pares blindados
Impedância característica: 150 Ohms
Largura de banda de 300 MHz em 100 m de cabo.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Par Trançado (UTP e STP)
Par Metálico Trançado:
Cabos UTP (“Unshielded Twisted Pairs”):
Classificação pels EIA/TIA
Impedância característica: 100 Ohms (24 AWG)
Aplicações Típicas:
Rede telefônica;
Ethernet;
Token Ring;
ATM.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Padrão IEEE 802.3
Especificações 10Base5, 10Base2 e 10BaseT:
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Padrão EIA / TIA 568A ( Strainght Through )
10BaseT e 100BaseT
Pino 8 Marrom Não Utilizado
Pino 7 Mr / Br Não Utilizado
Pino 6 Laranja - RD 
 
Pino 5 Az / Br Não Utilizado 
Pino 4 Azul Não Utilizado
 
Pino 3 Lr / Br + RD 
 
Pino 2 Verde - TD 
Pino 1 Vd / Br + TD 
 
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Padrão EIA / TIA 568A ( Strainght Through )
 1000BaseT (Gigabit Ethernet)
Pino 8 Marrom - BI_DD 
Pino 7 Mr / Br + BI_DD 
Pino 6 Laranja - RD 
 
Pino 5 Az / Br - BI_DC 
Pino 4 Azul + BI_DC 
 
Pino 3 Lr / Br + RD 
 
Pino 2 Verde - TD 
Pino 1 Vd / Br + TD 
 
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Padrão EIA / TIA 568B ( Half Cross )
10BaseT e 100BaseT
Pino 8 Marrom Não Utilizado
Pino 7 Mr / Br Não Utilizado
Pino 6 Verde - RD 
 
Pino 5 Az / Br Não Utilizado 
Pino 4 Azul Não Utilizado
 
Pino 3 Vd / Br + RD 
 
Pino 2 Laranja - TD 
Pino 1 Lr / Br + TD 
 
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Cabo Coaxial
Velocidade de transmissão: 10/100 Mbps 
Custo Relativo : 	 Mais caro que o UTP, porém 	 continua Baixo
Tamanho do conector:	 Médio
Comprimento máximo do cabo: 200 à 500m 
Revestimento 
Exterior
Malha de cobre
Isolação Plástica
Condutor de Cobre
Conector BNC
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Cabo Coaxial
Cabo Coaxial:
Condutor isolado dentro de tubo -> blindagem eletrostática metálico concêntrico;
Grande variedade de tipos;
Capacitância baixa  CTE -> altas taxas (Mbps);
Sistemas com transmissão em banda básica (50 Ohms);
Sistemas de TV a cabo e redes em banda larga (75 Ohms);
Aplicações Típicas:
Redes em banda larga;
Ethernet;
Token Ring.
Interface G 703:
Usa cabo coaxial para interligação de equipamentos;
Velocidades acima de 2 Mb
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Fibra Óptica
Monomodo: 	Somente um feixe de luz gerada (100 km)
Multimodo: 	Multiplos feixes de luz geradas (2 km)
Velocidade de transmissão: >	Gbps 
Custo Médio por nó : 	O mais caro
Tamanho do conector : 	Pequeno
Tamanho Máximo do cabo: 	100Km
Conector
Multimodo
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Fibra Óptica
Guia de onda luminosa (faixa de freqüência de infravermelho, 1014 a 1015Hz);
Material Dielétrico (sílica) -> imunidade às interferências e ruídos eletromagnéticos.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Fibra Óptica
Meio de transmissão recente -> média disponibilidade;
Suporta altas taxas de transmissão (centenas de Mbps);
Tipos:
Multimodo com índice degrau (d ~ 50 - 200um);
Multimodo com índice gradual (d ~ 50 - 100um);
Monomodo (d ~ 5 - 10um).
Atenuação: tipo 1 > tipo 2 > tipo 3
Aplicações Típicas:
Entroncamentos digitais (2, 8, 34 e 140 Mbits/s);
Ethernet;
Token Ring;
FDDI.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Espaço Livre ( wireless )
Meio natural de propagação 	grande flexibilidade na localização das estações
Suporte essencial aos terminais com necessidade de mobilidade
Custo dos equipamentos de 	redes locais  radiofusão + regulamentação 	wireless são do espectro de freqüência	pouco usuais
Aplicações Típicas:
Conexões ponto-a-ponto entre sub-redes locais
Comunicações militares
Serviços celulares.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
INTERFACES MECÂNICAS/ELÉTRICAS DTE/DCE
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS232 – V24
RS-232
Padrão por décadas de interface elétrica entre equipamentos DTE e DCE com velocidade máxima de 20 kbps.
Interface não-balanceada: Os sinais são transmitidos através de um nível de tensão referenciado ao terra comum (pino 7).
Espeficações: 
Mecânica:
		Conector DB25 		25 pinos (macho/fêmea)
		Conector DB9 		9 pinos (macho/fêmea)
Elétrica:
			Sinal > +3volts = 0		(Tipicamente os valores
			Sinal < -3volts = 1		oscilam entre +12v e -12v)
Limitações:
		Cabo máx - 15 mts
		Velocidade máx - 20 kbps 	(na prática, dependendo do cabo 			 	utilizado, este valor pode chegar 			 	até 64 kbps)
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS232
Várias nomenclaturas: RS-232C, RS-232D, V.24, V.28 ou V.10, porém essencialmente todas elas são inter-operáveis.
Utilizada para transferência de dados assíncrona assim como para links síncronos como SDLC, HDLC, X25, Frame Relay, etc.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS232
 Pinagem (cabo direto - pino a pino)
DTE
DCE
CONECTOR 
CONECTOR
SINAL
DB25 (m)
DB25 (m)
1
1
SHIELD
2
2
TXD 
3
3
RXD 
4
4
RTS
5
5
CTS
6
6
DSR
7
7
SGND
8
8
DCD
15
15
TXC - DCE
17
17
RXC - DCE
19
19
20
20
DTR
22
22
RING INDIC
24
24
XTXC - DTE
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO V.35
V.35
Padrão de interface elétrica entre equipamentos DTE e DCE para velocidades de 48 kbps.
Mistura de sinais balanceados e desbalanceados: Os sinais de controle DTR, DSR, DCD, RTS e CTS são desbalanceados (único fio referenciado ao terra comum). Os sinais de dados e clocks são balanceados (2 fios, circuitos A e B).
Especificações: 
Mecânica:
		Conector Winchester M34	34 pinos (macho/fêmea)
Elétrica:
			VA - VB < -0.55volts = 0	
			VA - VB > +0.55volts = 1	
Limitações:Dependendo do cabo utilizado não é incomum utilizar o V.35 	para aplicações que requeiram velocidades de até 2Mbps.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO V.35
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO V.35
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS449 – V36
RS-449
Padrão de interface elétrica entre equipamentos DTE e DCE para velocidades acima de 20 kbps.
2 configurações:	RS423 (CCITT V.10) - Linhas desbalanceadas
		RS422 (CCITT V.11) - Linhas balanceadas
Espeficações: 
Mecânica:
		Conector DB37 		37 pinos (macho/fêmea)
Elétrica:
		VA - VB < -0.2volts = 0	
			VA - VB > +0.2volts = 1	
Limitações (comprimento cabo x velocidade de transmissão):
		RS423 -> 50mts@20kbps; 10mts@100kbps
		RS422 -> 1000mts@100kbps; 50mts@2Mbps; 10mts@10Mbps
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS449 – V36
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
PADRÃO RS449
DTE
DCE
CONECTOR 
CONECTOR
SINAL
DB37 (m)
DB37 (m)
1
1
SHIELD
3
3
4
4
SD A 
5
5
ST A
6
6
RD A
7
7
RTS A
8
8
RT A
9
9
CTS A
11
11
DSR A
13
13
DCD A
16
16
17
17
TT A
19
19
SG
20
20
21
21
22
22
SD B
23
23
ST B
24
24
RD B
25
25
RTS B
26
26
RT B
27
27
CTS B
29
29
DSR B
31
31
DCD B
34
34
35
35
TT B
37
37
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Necessidade de Vazão
2,457,000 bits/screen
30 screens/second
73,728,000 bps
100,000 bits
64,000 bps
841,000 bits
202,000,000 bits
7,300,000 bits/screen
30 pictures/second
224,000,000 bps!!!
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Necessidade de Vazão X Banda
Taxa de Transmissão ( THROUGHPUT )
É a taxa de informação que chega a um nó da rede e deve ser transmitido para Outro nó.
Largura de Banda ( BANDWIDTH )
A capacidade total de um meio ou de um protocolo específico da rede
THROUGHPUT = BANDWIDTH - OVERHEAD
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Taxa de Transmissão
10,000 pages
= 53 MB
(Megabytes)
Velocidade
Tempo de 
Transmissão
9,600 bps
=
12.27
hrs
24,000 bps
=
4.91
hrs
56 Kbps
=
2.1
hrs
1 Mbps
=
7.1
min
10 Mbps
=
42.4
sec
100 Mbps
=
4.24
sec
1 Gbps
=
0.42
sec
1 Byte = 8 bits
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Prefixos das unidades de medida do Sistema Internacional (SI)
Plan1
		
		
		
		
		
		
		
		
		
		
				Prefixos das unidades de medida do Sistema Internacional (SI)
		
				Nome		Símbolo		Fator de multiplicação da unidade
				exa		E
				peta		P
				tera		T
				giga		G
				mega		M
				quilo		k		10³ = 1 000
				hecto		h		10² = 100
				deca		da		10
				deci		d
				centi		c
				mili		m
				micro		µ
				nano		n
				pico		p
				femto		f
				atto		a
				Fonte: INMETRO
Plan2
		
Plan3
		
MBD0007704F.bin
Topologias de LAN
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Topologias de LAN
Define a organização dos componentes da rede
Quatro Tipos mais usados
Topologia em Barramento
Topologia em Árvore
Topologia em Estrela
Topologia em Anel
Topologias são Arquiteturas Lógicas 
Os dispositivos reais não necessitam ser organizados fisicamente nestas configurações
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Barramento e Árvore
Topologia em 
Árvore - Multiplos 
Nós
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Topologia Estrela (LAN)
Ponto Central: HUB, repetidor, ou concentrador.
Tipicamente usado nas redes ETH e Token Ring
5 to 100+ equipamentos
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Topologia em Anel (LAN)
Instalação redundante
Cada estação funciona como repetidor 
Transmissão Unidirecional 
Loop fechado
Equipamentos LAN/WAN
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
 Hubs
 Bridges
 Switches
 Routers
EQUIPAMENTOS LAN/WAN
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Hub
Equipamento que serve como um concentrador em uma rede estrela, algumas vezes atua como um repetidor multiportas, ou nas redes ETH, como um concentrador sem nenhuma inteligência.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Hubs
Amplifica os sinais
Propagação de sinais pela rede
Não filtra os pacotes de dados: origem/destino
Não faz comutação de pacotes
Apenas um concentrador na rede
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Bridge
Dispositivo que conecta dois segmentos de rede
Mais inteligente que a HUB—analisa os pacotes de entrada e os seus destinos ( ou filtros ) baseados em endereçamento MAC.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Mais inteligente que a HUB —Analisa os pacotes de entrada e de destino (ou filtro ) baseados em endereçamento.
Coleta e transmite pacotes entre 2 segmentos de rede 
Cria tabela de endereçamento
Diferentes tipos de Brigde: Transparente e source route
Exemplos de Bridge
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Switches
Usa tecnologia de bridging para comutar os tráfego entre as portas. 
Prove taxa de transmissão dedicada entre 2 estações que estão diretamente conectadas às portas da swicth.
Constrói e mantém tabelas de endereçamento chamadas content-addressable memory (CAM).
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
10-Mbps
UTP Cable
“Dedicado”
Workstation
31
Switch
Intranet Corporativa
32
33
36
100 Mbps
100 Mbps
Usa tecnologia de bridging para encaminhar o tráfego 
Provê acesso dedicado com taxa de transmissão constante entre os equipamentos diretamente conectados na swicth.
Usada tanto nas local-area e nas wide-area networking
Estão disponíveis para todas Topologias —Ethernet, Token Ring, ATM
Switching—“Dedicated” Media
35
34
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Routers
Interconectam LANs e WANs
Provê determinação de rotas utilizando-se de métricas.
Encaminha pacotes de uma rede para outra.
Faz controle de broadcasts da rede.
Tradução: Kleber Aparecido Tomé
Fonte : Cisco Business Essentials
Fundamentos de Rede
Sumário
LANs são projetadas para operar dentro de uma área geográfica limitada
Os componentes chaves das LANs são computadores, NICs, HUBs, Swicthes, Routers e cabos
As Topologias comuns nas LAN são : Barramento, Árvore, Estrela e Anel. 
This module covers the very basics of internetworking. We’ll start with a little history that describes how the networking industry evolved. We’ll then move on to a section that describes how a LAN is built: essentially the necessary components (like NIC cards and cables). We then cover LAN topologies. And finally we’ll discuss the key networking devices: hubs, bridges, switches, and routers.
This module is an overview only. It will familiarize you with much of the vocabulary you hear with regards to networking. Some of these concepts are covered in more detail in later modules. 
Let’s start by looking at how the networking industry came about.
From a historical perspective, electroniccommunication has actually been around a long time, beginning with Samuel Morse and the telegraph. He sent the first telegraph message May 24, 1844 from Washington DC to Baltimore MD, 37 miles away. The message? “What hath God wrought.”
Less than 25 years later, Alexander Graham Bell invented the telephone – beating out a competitor to the patent office only by a couple of hours on Valentine’s Day in 1867. This led to the development of the ultimate analog network – the telephone system. 
The first bit-oriented language device was developed by Emile Baudot – the printing telegraph. By bit-oriented we mean the device sent pulses of electricity which were either positive or had no voltage at all. These machines did not use Morse code. Baudot’s five-level code sent five pulses down the wire for each character transmitted. The machines did the encoding and decoding, eliminating the need for operators at both ends of the wires. For the first time, electronic messages could be sent by anyone. 	
But it’s really the telephone network that has had the greatest impact on how businesses communicate and connect today. Until 1985, the Bell Telephone Company, now known as AT&T, owned the telephone network from end to end. It represented a phenomenal network, the largest then and still the largest today. 
Let’s take a look at some additional developments in the communications industry that had a direct impact on the networking industry today.	
In 1966, an individual named “Carter” invented a special device that attached to a telephone receiver that would allow construction workers to talk over the telephone from a two-way radio. 
Bell telephone had a problem with this and sued – and eventually lost.
As a result, in 1975, the Federal Communications Commission ruled that devices could attach to the phone system, if they met certain specifications. Those specifications were approved in 1977 and became known as FCC Part 68. In fact, years ago you could look at the underside of a telephone not manufactured by Bell, and see the “Part 68” stamp of approval. 
This ruling eventually led to the breakup of American Telephone and Telegraph in 1984, thus creating nine regional Bell operating companies like Pacific Bell, Bell Atlantic, Bell South, Mountain Bell, etc.	
The break up of AT&T in 1984 opened the door for other competitors in the telecommunications market. Companies like Microwave Communications, Inc. (MCI), and Sprint. Today, when you make a phone call across the country, it may go through three or four different carrier networks in order to make the connection. 
Now, let’s take a look at what was happening in the computer industry about the same time. 	
In the 1960’s and 1970’s, traditional computer communications centered around the mainframe host. The mainframe contained all the applications needed by the users, as well as file management, and even printing. This centralized computing environment used low-speed access lines that tied terminals to the host. 
These large mainframes used digital signals – pulses of electricity or zeros and ones, what is called binary -- to pass information from the terminals to the host. The information processing in the host was also all digital. 	
This brought about a problem. The telephone industry wanted to use computers to switch calls faster and the computer industry wanted to connect remote users to the mainframe using the telephone service. But the telephone networks speak analog and computers speak digital. Let’s take a closer look at this problem. 	
Digital signals are seen as one’s and zero’s. The signal is either on or off. Whereas analog signals are like audio tones – for example, the high-pitched squeal you hear when you accidentally call a fax machine. So, in order for the computer world to use the services of the telephone system, a conversion of the signal had to occur. 	
The solution – a modulator/demodulator or “modem.” The modem takes the digital signals from the computer and modulates the signal into analog format..	
In sending information from a desktop computer to a host using POTS or plain old telephone service, the modem takes the digital signals from the computer and modulates the signal into analog format to go through the telephone system. From the telephone system, the analog signal goes through another modem which converts the signal to digital format to be processed by the host computer.
This helped solve some of the distance problems, at least to a certain extent.	
Another problem is how to connect multiple terminals to a single cable. The technology solution is multiplexing or muxing.
What we can do with multiplexing is we can take multiple remote terminals, connect them back to our single central site, our single mainframe at the central site, but we can do it all over a single communications channel, a single line. 
So what you see is we have some new terminology here in our diagram. Our single central site we refer to as a broadband connection. That's referred to as a broadband connection because whenever we talk about broadband we're talking about carrying multiple communications channels over a single communication pipe. 
So what we're saying here is we have multiple communication channels as in four terminals at the remote site going back to a single central site over one common channel. 
But again in the case of our definition of broadband here, we're referring to the fact that we have four communication channels, one for each remote terminal over a single physical path. 
Now out at the end stations at the terminals, you see we have the term Baseband and what we mean by the term Baseband is, in our example, between the terminal and the multiplexer we have a single communication channel per wire, so each of those wires leading into the multiplexer has a dedicated channel or a dedicated path. 
Now the function of the multiplexer is to take each of those Baseband paths and break it up and allocate time slots. 
What that allows us to do is allocate a time slot per terminal so each terminal has its own time slot across that common Baseband connection between the remote terminals and the central mainframe site. 
That is the function of the multiplexer is to allocate the time slots and then also on the other side to put the pieces back together for delivery to the mainframe. 
So muxing is our fundamental concept here. Let’s look at the different ways to do our muxing. 
You see again the terms here, Baseband and broadband. 
Again, the analogy that they're using here is that in the case of Baseband we said we had a single communications channel per physical path. 
An example of some Baseband technology you're probably familiar with is Ethernet for example. 
Most implementations of Ethernet use Baseband technology. 
We have a single communications channel going over a single physical path or a single physical cable. 
On the other hand on the bottom part of our diagram you see a reference to broadband and the analogy here would be multiple trains inside of a single tunnel. 
Maybe we see that in the real world, we're probably familiar with broadband as something we do every day, is cable TV. 
With cable TV we have multiple channels coming in over a single cable. 
We plug a single cable into the back of our TV and over that single cable certainly we know we can get 12 or 20 or 40 or 60 or more channels over that single cable. 
So cable TV is a good example of broadband. 
Given the addition of multiplexing and the use of the modem, let’s see how we can grow our network.	
Using all the technology available, companies were able to team up with the phone company and tie branch offices to the headquarters. The speeds of data transfer were often slow and were still dependent on the speed and capacity of the host computers at the headquarters site.	
The phone company was also able to offer leased line and dial-up options. With leased-lines,companies paid for a continuous connection to the host computer. Companies using dial-up connections paid only for time used. Dial-up connections were perfect for the small office or branch. 	
The birth of the personal computer in 1981 really fueled the explosion of the networking marketplace. No longer were people dependent on a mainframe for applications, file storage, processing, or printing. The PC gave users incredible freedom and power. 	
The 70’s and 80’s saw the beginnings of the Internet. The Internet as we know it today began as the ARPANET — The Advanced Research Projects Agency Network – built by a division of the Department of Defense essentially in the mid ‘60's through grant-funded research by universities and companies. The first actual packet-switched network was built by BBN. It was used by universities and the federal government to exchange information and research. Many local area networks connected to the ARPANET with TCP/IP. TCP/IP was developed in 1974 and stands for Transmission Control Protocol / Internet Protocol. The ARPANET was shut down in 1990 due to newer network technology and the need for greater bandwidth on the backbone. 
In the late ‘70’s the NSFNET, the National Science Foundation Network was developed. This network relied on super computers in San Diego; Boulder; Champaign; Pittsburgh; Ithaca; and Princeton. Each of these six super computers had a microcomputer tied to it which spoke TCP/IP. The microcomputer really handled all of the access to the backbone of the Internet. Essentially this network was overloaded from the word "go".	
Further developments in networking lead to the design of the ANSNET -- Advanced Networks and Services Network. ANSNET was a joint effort by MCI, Merit and IBM specifically for commercial purposes. This large network was sold to AOL in 1995. The National Science Foundation then awarded contracts to four major network access providers: Pacific Bell in San Francisco, Ameritech in Chicago, MFS in Washington DC and Sprint in New York City. By the mid ‘80's the collection of networks began to be known as the “Internet” in university circles. TCP/IP remains the glue that holds it together. 
In January 1992 the Internet Society was formed – a misleading name since the Internet is really a place of anarchy. It is controlled by those who have the fastest lines and can give customers the greatest service today. 
The primary Internet-related applications used today include: Email, News retrieval, Remote Login, File Transfer and World Wide Web access and development.	
With the growth and development of the Internet came the need for speed – and bandwidth. Companies want to take advantage of the ability to move information around the world quickly. This information comes in the form of voice, data and video – large files which increase the demands on the network. In the future, global internetworking will provide an environment for emerging applications that will require even greater amounts of bandwidth. If you doubt the future of global internetworking consider this – the Internet is doubling in size about every 11 months.	
In the previous section, we discussed how networking evolved and some of the problems involved in the transmission of data such as conflict and multiple terminals. In this section some of the basic elements needed to build local area networks (LANs) will be described.
The term local-area network, or LAN, describes of all the devices that communicate together—printers, file server, computers, and perhaps even a host computer. However, the LAN is constrained by distance. The transmission technologies used in LAN applications do not operate at speed over long distances. LAN distances are in the range of 100 meters (m) to 3 kilometers (km). This range can change as new technologies emerge.
For systems from different manufacturers to interoperate—be it a printer, PC, and file server—they must be developed and manufactured according to industry-wide protocols and standards. 
More details about protocols and standards will be given later, but for now, just keep in mind they represent rules that govern how devices on a network exchange information. These rules are developed by industry-wide special interest groups (SIGs) and standards committees such as the Institute of Electrical and Electronics Engineers (IEEE).
Most of the network administrator’s tasks deal with LANs. Major characteristics of LANs are:
The network operates within a building or floor of a building. The geographic scope for ever more powerful LAN desktop devices running more powerful applications is for less area per LAN.
LANs provide multiple connected desktop devices (usually PCs) with access to high-bandwidth media.
An enterprise purchases the media and connections used in the LAN; the enterprise can privately control the LAN as it chooses.
LANs rarely shut down or restrict access to connected workstations; local services are usually always available.
By definition, the LAN connects physically adjacent devices on the media. 
So let’s look at the components of a LAN.
In order for computers to be able to communicate with each other, they must first have the networking software that tells them how to do so. Without the software, the system will function simply as a “standalone,” unable to utilize any of the resources on the network. 
Network operating software may by installed by the factory, eliminating the need for you to purchase it, (for example AppleTalk), or you may install it yourself. 
The computer shown here may be a workstation or a personal computer (PC).
 
In addition to network operating software, each network device must also have a network interface card. These cards today are also referred to as adapters, as in “Ethernet adapter card” or “Token Ring adapter card.”
The NIC card amplifies electronic signals which are generally very weak within the computer system itself. The NIC is also responsible for packaging data for transmission, and for controlling access to the network cable. When the data is packaged properly, and the timing is right, the NIC will push the data stream onto the cable. 
The NIC also provides the physical connection between the computer and the transmission cable (also called “media”). This connection is made through the connector port. Examples of transmission media are Ethernet, Token Ring, and FDDI.
In order to have a network, you must have at least two devices that communicate with each other. In this simple model, it is a computer and a printer. The printer also has an NIC installed (for example, an HP Jet Direct card), which in turn is plugged into a wiring hub. The computer system is also plugged into the hub, which facilitates communication between the two devices. 
Additional components (such as a server, a few more PCs, and a scanner) may be connected to the hub. With this connection, all network components would have access to all other network components. 
The benefit of building this network is that by sharing resources a company can afford higher quality components. For example, instead of providing an inkjet printer for every PC, a company may purchase a laser printer (which is faster, higher capacity, and higher quality than the inkjet) to attach to a network. Then, all computers on that network have access to the higher quality printer.
The wires connecting the various devices together are referred to as cables. 
Cable prices range from inexpensive to very costly and can comprise of a significant cost of the network itself. 
Cables are one example of transmission media. Media are various physical environments through which transmission signals pass. Common network media include twisted-pair, coaxial cable, fiber-optic cable, and the atmosphere (through which microwave, laser, and infrared transmission occurs). Another term for this is “physical media.” 
Note that not all wiring hubs support all medium types.
The other component shownin this slide is the connector. 
As their name implies, the connector is the physical location where the NIC card and the cabling connect. 
Registered jack (RJ) connectors were originally used to connect telephone lines. RJ connectors are now used for telephone connections and for 10BaseT and other types of network connections. Different connectors are able support different speeds of transmission because of their design and the materials used in their manufacture. 
RJ-11 connectors are used for telephones, faxes, and modems. RJ-45 connectors are used for NIC cards, 10BaseT cabling, and ISDN lines.
Cable is the actual physical path upon which an electrical signal travels as it moves from one component to another.
Transmission protocols determine how NIC cards take turns transmitting data onto the cable. Remember that we discussed how LAN cables (baseband) carry one signal, while WAN cables (broadband) carry multiple signals. There are three primary cable types:
Twisted-pair (or copper)
Coaxial cable and
Fiber-optic cable 
Unshielded twisted-pair (UTP) is a four-pair wire medium used in a variety of networks. UTP does not require the fixed spacing between connections that is necessary with coaxial-type connections. There are five types of UTP cabling commonly used as shown below:
Category 1:	Used for telephone communications. It is not suitable for transmitting data. 
Category 2:	Capable of transmitting data at speeds up to 4 Mbps. 
Category 3:	Used in 10BaseT networks and can transmit data at speeds up to 10 Mbps. 
Category 4:	Used in Token Ring networks. Can transmit data at speeds up to 16 Mbps. 
Category 5:	Can transmit data at speeds up to 100 Mbps. 
Shielded twisted-pair (STP) is a two-pair wiring medium used in a variety of network implementations. STP cabling has a layer of shielded insulation to reduce EMI. Token Ring runs on STP.
Using UTP and STP:
Speed is usually satisfactory for local-area distances. 
These are the least expensive media for data communication. UTP is cheaper than STP.
Because most buildings are already wired with UTP, many transmission standards are adapted to use it to avoid costly re-wiring of an alternative cable type. 
Coaxial cable consists of a solid copper core surrounded by an insulator, a combination shield and ground wire, and an outer protective jacket.
The shielding on coaxial cable makes it less susceptible to interference from outside sources. It requires termination at each end of the cable, as well as a single ground connection.
Coax supports 10/100 Mbps and is relatively inexpensive, although more costly than UTP.
Coaxial can be cabled over longer distances than twisted-pair cable. For example, Ethernet can run at speed over approximately 100 m (300 feet) of twisted pair. Using coaxial cable increases this distance to 500 m.
Fiber-optic cable consists of glass fiber surrounded by shielding protection: a plastic shield, kevlar reinforcing, and an outer jacket. Fiber-optic cable is the most expensive of the three types discussed in this section, but it supports 100+ Mbps line speeds.
There are two types of fiber cable: 
Single or mono-mode—Allows only one mode (or wavelength) of light to propagate through the fiber; is capable of higher bandwidth and greater distances than multimode. Often used for campus backbones. Uses lasers as the light generating method. Single mode is much more expensive than multimode cable. Maximum cable length is 100 km.
Multimode—Allows multiple modes of light to propagate through the fiber. Often used for workgroup applications. Uses light-emitting diodes (LEDs) as light generating device. Maximum cable length is 2 km.
Super servers, high-capacity workstations, and multimedia applications have also fueled the need for higher capacity bandwidths.
The examples on this slide shows that the need for throughput capacity grows as a result of a desire to transmit more voice, video, and graphics. The rate at which this information may be sent (transmission speed) is dependent how data is transmitted and the medium used for transmission. The “how” of this equation is satisfied by a transmission protocol. 
Each protocol runs at a different speed. Two terms are used to describe this speed: throughput rate and bandwidth.
The throughput rate is the rate of information arriving at, and possibly passing through, a particular point in a network.
In this chapter, the term bandwidth means the total capacity of a given network medium (twisted pair, coaxial, or fiber-optic cable) or protocol. 
Bandwidth is also used to describe the difference between the highest and the lowest frequencies available for network signals. This quantity is measured in Megahertz (MHz).
The bandwidth of a given network medium or protocol is measured in bits per second (bps).
Some of the available bandwidth specified for a given medium or protocol is used up in overhead, including control characters. This overhead reduces the capacity available for transmitting data. 
This slide shows the tremendous variation in transmission time with different throughput rates. In years past, megabit (Mb) rates were considered fast. In today’s modern networks, gigabit (Gb) rates are possible. Nevertheless, there continues to be a focus on greater throughput rates. 
As seen in the last slide, throughput is dependent on the bandwidth of the medium and the transmission protocol. 
You may hear the word topology used with respect to networks. “Topology” refers to the physical arrangement of network components and media within an enterprise networking structure. There are four primary kinds of LAN topologies: bus, tree, star, and ring.
Bus topology is 
A linear LAN architecture in which transmissions from network components propagate the length of the medium and are received by all other components. 
The bus portion is the common physical signal path composed of wires or other media across which signals can be sent from one part of a network to another. Sometimes called a highway.
Ethernet/IEEE 802.3 networks commonly implement a bus topology
Tree topology is 
Similar to bus topology, except that tree networks can contain branches with multiple nodes. As in bus topology, transmissions from one component propagate the length of the medium and are received by all other components. 
The disadvantage of bus topology is that if the connection to any one user is broken, the entire network goes down, disrupting communication between all users. Because of this problem, bus topology is rarely used today.
The advantage of bus topology is that it requires less cabling (therefore, lower cost) than star topology.
Star topology is a LAN topology in which endpoints on a network are connected to a common central switch or hub by point-to-point links. Logical bus and ring topologies re often implemented physically in a star topology.
The benefit of star topology is that even if the connection to any one user is broken, the network stays functioning, and communication between the remaining users is not disrupted.
The disadvantage of star topology is that it requires more cabling (therefore, higher cost) than bus topology.
Star topology may be thought of as a bus in a box.
			
Ring topology consists of a series of repeaters connected to one another by unidirectional transmission links to form a single closed loop. 
Each station on the network connects to the network at a repeater. 
While logically a ring, ring topologies are most often organized in a closed-loop star. A ring topology that is organized as a star implements a unidirectional closed-loop star, instead of point-to-point links.
One example of a ring topology is Token Ring.
Redundancy is used to avoid collapse of the entire ring in the event that a connection between two components fails.
 
Let’s now take a look at some of the devices that move traffic around the network. 
The approach taken in this section will be simple. As networking technology continues toevolve, the actual differences between networking devices is beginning to blur slightly. Routers today are switching packets faster and yielding the performance of switches. Switches, on the other hand, are being designed with more intelligence and able to act more like routers. Hubs, while traditionally not intelligent in terms of the amount of software they run, are now being designed with software that allows the hub to be “intelligent” acting more like a switch. 
In this section, we’ll keep these different types of product separate so that you can understand the basics. Let’s start off with the hub. 
Star topology networks generally have a hub in the center of the network that connects all of the devices together using cabling. When bits hit a networking device, be they hubs, switches, or routers, the devices will strengthen the signal and then send it on its way. 
A hub is simple a multiport repeater. There is usually no software to load, and no configuration required (i.e. network administrators don’t have to tell the device what to do). 
Hubs operate very much the same way as a repeater. They amplify and propagate signals received out all ports, with the exception of the port from which the data arrived. 
For example, if system 125 wanted to print on the printer 128, the message would be sent to all systems on Segment 1, as well as across the hub to all systems on Segment 2. System 128 would see that the message is intended for it and would process it. 
Devices on the network are constantly listening for data. When devices sense a frame of information that is addressed (and we will talk more about addressing later) for it, then it will accept that information into memory found on the network interface card (NIC) and begin processing the data. 
In fairly small networks, hubs work very well. However, in large networks the limitations of hubs creates problems for network managers. In this example, Ethernet is the standard being used. The network is also baseband, only one station can use the network at a time. If the applications and files being used on this network are large, and there are more nodes on the network, contention for bandwidth will slow the responsiveness of the network down. 
Bridges improve network throughput and operate at a more intelligent level than do hubs. A bridge is considered to be a store and forward device that uses unique hardware addresses to filter traffic that would otherwise travel from one segment to another. A bridge performs the following functions:
Reads data frame headers and records source address/port (segment) pairs
Reads the destination address of incoming frames and uses recorded addresses to determine the appropriate outbound port for the frame.
Uses memory buffers to store frames during periods of heavy transmission, and forwards them when the medium is ready.
Let’s take a look at an example. 
The bridge divides this Ethernet LAN into two segments, each connecting to a hub and then to a bridge port. Stations 123-125 are on segment 1 and stations 126-128 are on segment 2. 
When station 124 transmits to station 125, the frame goes into the hub (who repeats it and sends it out all connected ports) and then on to the bridge. The bridge will not forward the frame because it recognizes that stations 124 and 125 are on the same segment. Only traffic between segments passes through the bridge. In this example, a data frame from station 123, 124, or 125 to any station on segment 2 would be forwarded, and so would a message from any station on segment 2 to stations on segment 1. 
When one station transmits, all other stations must wait until the line is silent again before transmitting. In Ethernet, only one station can transmit at a time, or data frames will collide with each other, corrupting the data in both frames. 
Bridges will listen to the network and keep track of who they are hearing. For instance, the bridge in this example will know that system 127 is on Segment 2, and that 125 is on segment 1. The bridge may even have a port (perhaps out to the Internet) where it will send all packets that it cannot identify a destination for. 
Switches use bridging technology to forward traffic between ports. They provide full dedicated transmission rates between two stations that are directly connected to the switch ports. Switches also build and maintain address tables just like bridges do. These address tables are known as “content addressable memory.” Let’s look at an example.
Replacing the two hubs and the bridge with an Ethernet switch provides the users with dedicated bandwidth. Each station has a full 10Mbps “pipe” to the switch. With a switch at the center of the network, combined with the 100Mbps links, users have greater access to the network. 
Given the size of the files and applications on this network, additional bandwidth for access to the sever or to the corporate intranet is possible by using a switch that has both 10Mbps and 100Mbps Fast Ethernet ports. The 10Mbps links could be used to support all the desktop devices, including the printer, while the 100Mbps switch ports would be used for higher bandwidth needs. 
A router has two basic functions, path determination using a variety of metrics, and forwarding packets from one network to another. Routing metrics can include load on the link between devices, delay, bandwidth, and reliability, or even hop count (i.e. the number of devices a packet must go through in order to reach its destination). 
In essence, routers will do all that bridges and switches will do, plus more. Routers have the capability of looking deeper into the data frame and applying network services based on the destination IP address. Destination and Source IP addresses are a part of the network header added to a packet encapsulation at the network layer.