Transcript LAN BASICS

CHAPTER
Network Hardware
Chapter Objectives
• Describe the important basic network
hardware and the internetworking
hardware
• Discuss the desired characteristics of a
server and a workstation
• Present different switching technologies
• Examine the routing process with the
help of an example
Classification of Basic Network
Hardware Components
• Network Interface Cards (NICs)
• Cables
• Connectors
• Servers
• Workstations
Classification of Internetworking
Hardware Components
• Line drivers or repeaters
• Transceivers
• Intelligent hubs
• Bridges
• Switches
• Routers
• Gateways
Chapter Modules
• Network interface cards
• Network connectors and hubs
• Server and workstation hardware
• Repeater
• Bridge
• Switch
Continued..
Continuation of Chapter
Modules
• Switching technology
• Router
• Gateway
END OF CHAPTER
INTRODUCTION
MODULE
Network Interface Cards (NICs)
Network Interface Card Types
• 10BaseT cards
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–
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Physical star networks
10 Mbps speed
Ethernet standard
Twisted pair wiring
• 10base2 cards
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–
–
–
Physical bus networks
10 Mbps speed
Ethernet standard
Thin coaxial wiring
Continuation of NIC Types
• 10Base5
– 10 Mbps speed
– Ethernet standard
– Thick coaxial wiring
• 100BaseTX
– 100 Mbps speed
– Fast Ethernet standard
– Twisted pair
• Higher quality Category 5 wires are
recommended
Token Ring Cards
• Token ring network cards
• Earlier token ring cards
– 4 Mbps
• Newer token ring cards
– 16 Mbps
Bus Types for NICs
• Card connector types
– Newer PCI bus
– Older ISA, VESA and EISA bus types
• ISA bus width
– 16-bit
• PCI bus width
– Usually 32-bit
– Supports 64-bit as well
• Used in high-powered network servers
Cable Connections for NICs
• BNC barrel connector
– Thin coaxial
• RJ 45
– Twisted pair
AUI and Combo Cable
Connections for NICs
• AUI Possibilities
– Designed for a thick coaxial cable
– Designed for a token ring network
– Provided for connecting a transceiver
• Combo Cards
– Consisting of different ports
– BNC, RJ-45, AUI
Possible Combo Card
Connections
• Thin coaxial cables (BNC)
• Twisted pair wires (RJ-45)
• Thick coaxial cables (AUI)
Description of an Actual NIC
• 10BaseT, PCI card
–
–
–
–
–
10 = speed in Mbps
Base =Ethernet
T = Twisted pair
32-bit = bus width
PCI = bus technology
END OF MODULE
MODULE
Sample Network Interface Cards
Example of a 10Base2 Card
BNC
Source: Black Box
Example of a 10BaseT Card
ISA
RJ 45
Source: Black Box
Example of a Combo Card
RJ 45
Combo
Source: Black Box
BNC
END OF MODULE
MODULE
Network Connectors and Hubs
Simple Connectors
• T connectors
– An interface between the NIC and the
cables
• Terminators
– Used at both ends of a bus network
T Connector
Terminator
Example of T-Connector and
Terminator
T Connector
Source: Black Box
Terminator
Connectors : Hubs
• Types
– Active hub
– Passive hub
• Passive hubs
– Simply provides the physical and the
electrical connection for the network
• Active hubs
– Has built-in intelligence
– Some are manageable hubs
Connectors : Passive Hub
MAU
WS
WS
Hub Connecting A Token-ring Network
WS
An Active Hub
WS
Backbone
WS
WS
Remote
Workstation
Remote Monitor
Active Hub
Hub Management Software
• Sophisticated
• Monitor the network traffic through
each of the ports
• Becoming popular
• Standardized protocol for remote
management exists
– SNMP (Simple Network Management
Protocol)
Example of a Hub Used in Ring
Network
Source: Black Box
Example of Hubs Used in the
Star Network
Stackable
Hubs
Source: Black Box
END OF MODULE
MODULE
Server and Workstation
Hardware
Module Objectives
• Give an overview of the different types
of the server hardware
• Discuss the desired characteristics of a
server
• Provide a specification for a
workstation
Servers
• Backbone of a network
• Types
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–
–
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Powerful micros
Servers
Super-servers
Sometimes mini-computers are used as
servers
• In a client-server, the server also acts as
an engine of database execution
• In general, it is used for the sharing of
Desired Characteristics of Server:
Processor and Storage
Requirement
• Powerful processor
– Latest Pentium Processor
– Multiple processors, if appropriate
• Large storage space
– Several gigabytes at a minimum
– Actual requirement will vary LAN size
• Fast disk access speed
– Less than 10 ms
Desired Characteristics of a
Server: CD-ROM
• Fast CD-ROM drives
• CD-ROM towers are often preferred
Desired Characteristics of Server:
Storage Technology
• Better hard disk technology
– SCSI
• Fast access
• Daisy chaining of devices
– Latest SCSI technology is required
• Possible consideration given to fiberchannel in the future
Desired Characteristics of Server:
Bus and Memory Technologies
• Better bus technology
– PCI
• Memory
– In excess of 128 Mbytes
– SDRAM or similar memory technology
functioning at 10 nanoseconds or less
– The 128-pin SDRAM is also known as the
DIMM chips as opposed to the 72-pin
SIMM chips
Desired Characteristics of Server:
Reliability
• Good back-up facilities
– Back-up tape
• Uniterruptible Power Supply (UPS)
Fault Tolerant Feature for
Servers
• RAID storage technology
– A system based on multiple disk
– Hot-swappable disks
• Redundant power supply
– Hot-swappable power supply
Workstation
• Most applications are executed at the
workstation
• Therefore, it must be powerful in terms
of the processor and the memory
• As a rule of thumb, the workstation
must be as powerful as it were to be
used as a standalone unit to run the
applications
Workstation Processor and
Memory
• Powerful processor
– Pentium class processor
• Adequate memory
– 32 Mbytes or more
– DIMM preferred although fast EDO SIMM
may also be used
Workstation Storage and
Compatibility
• Sufficient storage
– Storage in gigabytes
– Important in a client-server environment
– Front-end tools are stored on the
workstation
• Speed of storage
– Ultra DMA or SCSI preferred
– EIDE may also be used
• Hardware components with
Reliability
• Power surge protector
• Uninterruptible Power Supply (UPS),
for critical applications
END OF MODULE
MODULE
Repeater
An Overview of Repeaters
• Used for extending the physical span of
a network
– An example is the extension of the distance
between a hub and a node
• Span is often limited by design
considerations
• 10base5
– The span is limited to 500 meters
A Repeater Connection
Expanding the Span of the Network
Source: Black Box
Another Example of Repeater
Connection
Extending the distance between the backbone and the nodes.
Source: Black Box
Operations of a Repeater Within
the ISO OSI Model
• Operates at the lower level of the ISO
OSI model
– Physical layer
Physical
Layer
Medium
Repeater
Physical
Layer
Medium
Other Devices Used for
Extending the Span of a Network
• Line Drivers
• Short-Haul Modems
END OF MODULE
MODULE
Bridge
An Overview of a Bridge
• A device used for connecting two LANs
operating under the same protocol
• Currently, the term bridge is loosely
being used to describe different
interconnecting devices
– Used now for connecting LANs operating
under different protocols as well
Purpose of a Bridge
• Facilitate the movement of data packet
from one network segment to another
• Not a sophisticated internetworking
device
• Bridge does not perform the routing of
information to different segments of a
network
• Connects two network segments and
not multiple network segments
Bridge : ISO-OSI Layer of
Operation
Data
Link
Layer
Data
Link
Layer
Bridge
Physical
Layer
Physical
Layer
X Medium
X Medium
A simple bridge operates at the
second layer of the ISO model.
Practical Bridge Implementations
• Local Bridge
• Remote Bridge
Local and Remote Bridges
• Local bridge
– Connects two different LANs located
locally
• Remote bridge
– Connects LAN segments that are
geographically apart
– An example is a device that provide dialup access to a LAN
A Practical Bridge Example
Source: Black Box
END OF MODULE
MODULE
Switch
Switch Definition and Purpose
• A switch is defined as a device that
allows a LAN to be segmented
– The segments will operate under the same
protocol
Difference Between a Switch and
a Bridge
• A switch focuses on segmenting a LAN
• A bridge is concerned with linking two
network segments that operate under
different protocols
Purpose of a Switch
• Improve the network performance and
reliability
• Better manage the network in general
Performance Improvement in
Segmented Networks
• Performance is improved especially in the
case of a bus network
• Multiple bus paths are now available for
communication
• Each segment can engage in simultaneous
communication within itself
• Easier to isolate a problem to a segment
– Thus, better manage the entire network
Network Reliability
• When one segment does not function,
the other segments can continue to
function
– Offers better reliability to at least part of
the function
Switches in Ethernet and Token
Ring LANs
• Switches were originally designed for
segmenting Ethernet LANs
– Used extensively in configuring large
Ethernet bus LANs
• Physically the network configured would still
largely remain based on the star topology
• Switches are now available for token
ring networks as well
Use of Switches in Linking LAN
Segments
Crossover Traffic
Switch
Segment 2
Segment 1
Hub
WS
Server
Hub
WS
Server
Using A Switch to
Link Bus LAN Segments
Switch
Segment 1
Segment 2
Use of Switches in
Internetworking
• Because the typical inter-networking
connection involves multiple segments,
the use of a switch is more common
than the use of a bridge
Use of Switches for Higher
Bandwidth
100 MBps Switch
WS
WS
WS
WS
Each port in theory has a bandwidth of 100 Mbps.
END OF MODULE
MODULE
Switching Technology
Module Objectives
• Explain the basic operation of a switch
• List the switching technologies and
describe their operation
– Cut-through and store-and-forward
technologies
The Basic Operation of Switches
Receiver’s Address Sender’s Address Data
• A data packet is analyzed
• Receiver’s addresses is checked
• If it indicates the receiver to be in the
same segment, the packet is dropped
• If it indicates the receiver to be in a
different segment, the packet is
Switching Technologies
• There are two major types of switching
technologies
– Cut-through
– Store-and-forward
Cut-Through Technology
• Reads only part of the packet
– The addresses header
– Packet is forwarded accordingly
• Bad packets are not filtered
Store-and-Forward Technology
• Entire packet is processed
• Packets are filtered
– Bad packets are filtered
Switching Technology
Comparison
Header
Sender’s Add
Cut-through
Store-and-forward
Receivers Add
Data
Switching Technology Operation
at the ISO Layer
• In each of the two cases of switching
technologies no protocol conversion
takes place
• Forwarding and filtering are done at the
MAC layer
END OF MODULE
MODULE
Routers
The Purpose of a Router
• Connect LANs operating under
different protocols
• The LANs connected are better known
as sub-networks instead of network
segments
– The term segments is nevertheless used in
practice
Router Characteristics
• A router true internetworking device
– Connects different sub-networks together
• Establishes a logical path of
communication between the subnetworks
• Contributes to the modular
construction of a network
– Network itself is better managed
– Network resources are better utilized
Internetworking with a Router
IEEE 802.3
Sub-network
Router
PC-NFS
Sub-network
IEEE 802.5
Sub-network
Routers, Switches and Hubs in
Perspective
Backbone
Router
Switch
Switch
Hub
S
WS
Hub
S
Sub-network 1
WS
Hub
WS
S
Hub
WS
WS
S
WS
Sub-network 2
Difference Between Routers,
Switches and Hubs
• Hubs
– Simply provides the mechanical and
electrical connections between the nodes
• Switches
– Examine the data packet for the destination
address
– Do not alter the data packets
• Routers
– Examine and alter the data packets
– Perform protocol conversion
Router Requirements
• Requires more processing power
compared to switches and bridges
• Operations fall within the network
layer of the ISO-OSI communication
model
Router : Network Layer Interface
NETWORK
LAYER
DATA LINK
LAYER
ROUTER
NETWORK
LAYER
DATA LINK
LAYER
PHYSICAL
LAYER
PHYSICAL
LAYER
X MEDIUM
X MEDIUM
Layer 3
Layer 2
Layer 1
Switches
Devices and Layers
NETWORK
LAYER
Routers
DATA LINK
LAYER
Switches
PHYSICAL
LAYER
Repeaters
A Practical Router Example
Router
Router
Router
Source: Black Box
Router
Router
END OF MODULE
MODULE
Gateway
An Introduction to Gateways
• Gateways are comprehensive
internetworking devices
• They can be computers themselves
Gateways in the Past
• Very popular
• They were the only devices that could
be used for internetworking
• Computers of the past were not
designed with network connections in
mind
– Interconnection of different computer
systems has to be managed and driven by
an advanced device such as a gateway
The Present Scenario
• Computers are now designed with due
consideration given to network
connections
• Larger networks could today be
configured using internetworking
devices
– Routers, switches, hubs etc.
Use of Gateways at Present
• Used in the rare occasion when neither
of the internetworking devices could be
used for connecting the sub-networks
together
• Example
– Connection of a legacy mainframe system
to a bus LAN
Rule of Thump
• Gateways are used for interconnecting
vastly differing computing
environments together
SNA Gateway
SNA
Gateway
NIC Card
WS
WS
LAN - Ethernet
FEP
Mainframe
Gateway
Interface
Card
Gateway
software
IBM - SNA
Gateway’s Functional Relationship
to the ISO-OSI Model
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
Network
Network
Data Link
Data Link
Physical
Physical
END OF MODULE
END OF MODULE
END OF CHAPTER