Switches and Routers.ppt
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Transcript of Switches and Routers.ppt
CHAPTER CHAPTER
Network HardwareNetwork 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 END OF CHAPTER INTRODUCTIONINTRODUCTION
MODULE
Network Interface Cards (NICs)
Network Interface Card Types
• 10BaseT cards– Physical star networks– 10 Mbps speed– Ethernet standard– Twisted pair wiring
• 10base2 cards– 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 MODULEEND OF MODULE
MODULE
Sample Network Interface Cards
Example of a 10Base2 Card
BNC
Source: Black Box
Example of a 10BaseT Card
RJ 45
ISA
Source: Black Box
Example of a Combo Card
Combo
Source: Black Box
RJ 45
BNC
END OF MODULEEND 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
TerminatorT Connector
Example of T-Connector and Terminator
T Connector
TerminatorSource: Black Box
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
Backbone
Man
ag
eab
l e H
ub
RemoteWorkstation
WS
WS
WSRemote 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
StackableHubs
Source: Black Box
END OF MODULEEND 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
– 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 stored data and application
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 fiber-channel 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 appropriate drivers for the client operating system
Reliability
• Power surge protector• Uninterruptible Power Supply
(UPS), for critical applications
END OF MODULEEND 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
Medium
PhysicalLayer
Repeater
Medium
Physical Layer
Other Devices Used for Extending the Span of a
Network
• Line Drivers• Short-Haul Modems
END OF MODULEEND 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
Bridge : ISO-OSI Layer of Operation
X Medium X Medium
Physical Layer
PhysicalLayer
DataLink
Layer
DataLink Layer
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
dial-up access to a LAN
A Practical Bridge Example
Source: Black Box
END OF MODULEEND 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
Switch
Hub Hub
WS Server WS Server
Segment 1 Segment 2
Crossover Traffic
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
WS
Use of Switches for Higher Bandwidth
100 MBps Switch
WS WS WS
Each port in theory has a bandwidth of 100 Mbps.
END OF MODULEEND 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
• 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 forwarded to a different segment
Receiver’s Address Sender’s Address Data
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 Receivers Add Data
Cut-through
Store-and-forward
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 MODULEEND 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 sub-networks
• Contributes to the modular construction of a network– Network itself is better managed– Network resources are better utilized
Internetworking with a Router
IEEE 802.3Sub-network IEEE 802.5
Sub-network
PC-NFSSub-network
Router
Routers, Switches and Hubs in Perspective
Switch Switch
HubHub
S WS WSWS
Router
Hub
S WS
Hub
WSS
Hub
WSWS
Hub
WSS
Sub-network 1 Sub-network 2
Backbone
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
X MEDIUM X MEDIUM
PHYSICAL LAYER
PHYSICALLAYER
DATA LINKLAYER
DATA LINKLAYER
NETWORKLAYER
ROUTERNETWORK
LAYER
Devices and Layers
PHYSICAL LAYER
DATA LINKLAYER
NETWORKLAYER
Switches
Routers
Repeaters
Sw
itch
es
Layer 1
Layer 2
Layer 3
A Practical Router Example
Router
Router
Router
Router
Router
Source: Black Box
END OF MODULEEND 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
WS WS
Main
fram
e
LAN - Ethernet
IBM - SNA
FEPNIC Card
Gateway software
GatewayInterface
Card
Gateway’s Functional Relationship to the ISO-OSI
ModelApplication
Presentation
Session
Transport
Network
Data Link
Physical
Gateway
Application
Presentation
Session
Transport
Network
Data Link
Physical
END OF MODULEEND OF MODULE
END OF MODULE END OF MODULE
END OF CHAPTER END OF CHAPTER