Chapter 6Local Area Network Hardware

• LAN Technology Architecture

• Network Interface Cards

• Wiring Center

• LAN Switches

• Media

LAN Technology Architecture

• Shared-media LAN

• Switched LAN

Shared- Media LAN

• Sharing available bandwidth among all devices

• 100BaseT, 100VG-Any-LAN, isochronous Ethernet

Switched LAN

• Dedicated (guaranteed) bandwidth to switch connected devices (point-to-point)

• Limited number of simultaneous point-to-point connections

• Replace the media-sharing LAN for more bandwidth

Full-Duplex Network Architectures

• Special type of switched LAN

• Full-duplex Ethernet, full-duplex token ring, full-duplex FDDI

• Full-duplex Ethernet NICs, full-duplex NIC drivers, and full-duplex Ethernet switches

Network Interface Cards (NICs)Functions

• Physical link between devices

• Pass data between devices

• Determine the network architecture and protocol

NICs - Technology Analysis• Bus Type

– ISA, EISA, MCA, NuBus (Apple), PCI, PCMCIA, Sbus (Sun)

– Internal/external or external interface to parallel port

• Data transfer technique– Bus-mastering DMA (direct memory access)

– DMA(direct memory access)

– Shared memory

– Program I/O

• Media interfaces (cables & connectors)

• Network drivers

• Management tools

• Other hardware requirements– On-board processor capabilities

– On-board memory

– System memory requirements

Bus Types

• Industry Standard Architecture (ISA): 8-bit or 16-bit

• Microchannel Architecture (MCA): 32-bit• Extended Industry Standard Architecture (EISA):

8-bit, 16-bit, 32-bit• Local bus

– Video Electronics Standards Association (VESA local bus or VL-Bus)

– Peripheral Component Interconnect (PCI local bus)

• Advanced graphic port by Intel

NICs - Trends

• Dual-speed cards: 10/100 Mbps

• Integrated or on-board NICs

• Multiport NICs

• On-NIC virus protection and security

• Integrated repeater modules (up to seven devices)

• Full-duplex mode

• Performance improvement

NIC Drivers

• Functions: communication between NIC and PC’s operating system

• Types:– Monolithic drivers– Multiprotocol network interface card drivers

• NDIS (network driver interface specification) by Microsoft & 3Com

• ODI (open data-link interface) by Novell & Apple

– PCMCIA (PC Card or CardBus) drivers: card and socket services (CSS)

PCMCIA

• Personal Computer Memory Card Interface Association

• People Can’t Master Computer Industry Acronyms

Wiring Center

• For Shared-media LAN

• Types– Stand-along hubs– Stackable hubs– Multistation access units– Enterprise hubs

Stand-along Hubs

• Repeaters– Retiming & regenerating digital signals– Linking devices or LAN segments of similar

network architecture

• Hubs– Subset of repeaters– Connect single devices to its ports– Concentrator or intelligent concentrator

Stackable Hubs

• Cascading ports for hubs

• Specialized hub-to-hub cables

• Expandability and manageability

• Stackability ranging from 4 to 20

Multistation Access Units

• MAU: token ring hub

• Shielded twisted pair with Type 1 connectors

• Eight ports with additional ports: RI (ring in) & RO (ring out) for cascading

• Active-management MAUs with identifying and removing malfunctioning token ring adapters

Enterprise Hubs

• Modular concentrators or network in a box• Modular design and chassis-based architecture• Hot-swappable: inserting and removing module

with power on• Types of modules

– Ethernet, token ring, & FDDI port modules

– Management modules: security, encryption, authorization modules

– Internetworking modules: router & bridge modules

– Multiple power supplies for redundant power

• Media: UTP, STP, thick or thin coax, & fiber

Hub Management

• Software– Local hub management software– Enterprise network management software: HP’s

Open View, IBM’s NetView, Sun’s SunNet Manager, Novell’s NMS

• Standard protocol– Simple network management protocol (SNMP)– Management information bases (MIB)– Remote monitoring (RMON) MIB

Wiring Center Analysis

• Expendability

• Reliability

• Network architecture

• Media

• Internetworking: WAN, LAN, different types

• Management

Wiring Center Management

• Operating system

• Faults

• Alarms

• Statistics

• Security

• Remote

• SNMP

LAN Switches: Architectures

• Stand-alone switches or slide-in modules for enterprise switches:– Ethernet switches– Token ring switches– FDDI switches– Fast Ethernet switches

• Super-Switches or Mega-Switches support– Multiple different LAN– ATM– WAN

LAN Switch Methods• Cut-through switches

– Fast– No error checking– Retransmitting

• Store-and-forward switches– Slow– Error checking

• Error-free cut-through switches– Error checking– Switch between cut-through & store-and-

forward depend on line condition

Switch Management

• Flow control– Buffers– Backpressure: false collision detection signal

• Monitoring– Port mirroring– Roving port mirroring– Simultaneous RMON view using a shared

memory multigigabit bus

LAN Switch Analysis

• Switching methods: cut through, stored and forward, error free stored and forward

• Network architecture: Ethernet, token ring, FDDI, etc

• Port configuration and connection: single device or multiple devices

• Full-duplex

• Internetworking: routing or bridge or both

• Management: SNMP

ATM for LAN

• IP over ATM– TCP/IP protocol stack to employ ATM services

• LAN emulation– A translation layer to use ATM services

LAN Media Alternatives

• Not twisted pair

• Unshielded twisted pair

• Shielded twisted pair

• Coaxial cable

• Fiber

• Microwave radio

• Satellite

• Infrared

Not Twisted Pair: Phone Wire

• Four-conductor station wire (RYGB)– Not for data transmission

• Flat gray modular wire or gray satin or silver satin– Data over short distance

Unshielded Twisted Pair • 22, 24, 26 American wire gauge(AWG)• Twisted pair or unshielded twisted pair (UTP)• Electrical noise & other interference• Electrical Industries

Association/Telecommunications Industries Association (EIA/TIA): 5 grades (Cat 3 & Cat 5: data grade)– Attenuation

– Near-end crosstalk (NExT)

• Category 6– Foil-twisted pair cable

– Data rate: 600 MHz

UTP Installation Mistakes

• Untwisting more than max 13 mm to wall plates or punch-down block

• Exceed maxi bend radius (increase cross talk)

• Tight wires too tight (cross talk)

Shielded Twisted Pair

• Pros:– Less interference– Faster speed

• Cons:– More expensive– Physically larger and difficult to connect to a

terminating block

Coaxial Cable

• Pros:– Large bandwidth (400 - 600 MHz)– High capacity– Less interference– Good for noise environment

• Cons:– Tapped easy (security problem)– Bulky to install

Fiber - I• Types:

– Single mode: more expensive and capacity

– Multimode graded index: medium expensive and capacity

– Multimode or multimode step index: less expensive and capacity

– Inexpensive plastic or copper

– Expensive glass

• Pros:– High bandwidth

– No interference

– No crosstalk

– Small physical size and light weight

– Very secure

• Cons:– Repeater for long distance

– Expansive

Fiber - II

• Standard– Synchronous optical network (SONET) in US– Synchronous digital hierarchy (SDH) in Europe

• Main cable - TAT-8– 6 fiber optic– 2 pairs for voice, video, and data– 1 pairs for backup– Regenerator every 43 miles

Microwave Radio - I

• Characteristics– Long distance– 4-28 gHz frequency range– Straight line transmission– 20-30 miles between transmission towers– Radio license by FCC

Microwave Radio - II

• Pros:– Analog or digital signals

– For voice, data and television signals

– Long distance

• Cons:– Interference by heavy rain

– Straight line transmission

– Security

• Vendors– Motorola

– Rockwell Communication Systems

Satellite• Characteristics:

– Microwave radio transmission

– Uplink and downlink

– Three satellites for the earth

• Pros:– Analog or digital signals

– For voice, data and television signals

– Long distance

• Cons:– Security and encryption

– Propagation delay

Infrared

• Light waves

• Line of sight

• Wireless communication between nearby equipment

Circuit Ownership

• Private circuits

• Leased circuits

• Bypass

• Switched (dial-up) circuits

• Selection criteria– Cost, speed, availability, reliability,

maintenance, users’ requirements

Circuit Identification

• Blue prints and document circuit and equipment

• Circuit number to each circuit for identification

Assignment

• Review chapters 5-6

• Read chapter 7