Chapter 11 Modern Computer Systems, Clusters, and Networks The Architecture of Computer Hardware and Systems Software: An Information Technology Approach 3rd Edition, Irv Englander John Wiley and Sons 2003 Wilson Wong, Bentley College Linda Senne, Bentley College
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Chapter 11 Modern Computer Systems, Clusters, and Networks The Architecture of Computer Hardware and Systems Software: An Information Technology Approach.
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Chapter 11Modern Computer Systems, Clusters, and Networks
The Architecture of Computer Hardware and Systems Software:
An Information Technology Approach
3rd Edition, Irv Englander
John Wiley and Sons 2003
Wilson Wong, Bentley College
Linda Senne, Bentley College
Chapter 11: Modern Computer Systems, Clusters, and Networks
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Basic Personal Computer System
Chapter 11: Modern Computer Systems, Clusters, and Networks
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Mainframe Computer System
Chapter 11: Modern Computer Systems, Clusters, and Networks
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Major PC System Components
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System Performance Improvements Multiple CPUs Faster clock speed, buses and circuits Wider instruction and data paths Faster disk access More and faster memory
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Multiprocessing
Reasons Increase the processing power of a system Parallel processing
Types of multiprocessor systems Tightly coupled systems Loosely coupled systems
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Tightly Coupled Systems
Also called multiprocessor systems Identical access to programs, data,
shared memory, I/O, etc. Easily extends multi-tasking, and
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LAN Topologies: Bus
Multipoint medium Stations attach to linear medium (bus)
using tap Transmission from any stations travels
entire medium (both directions) Termination required at ends of bus to
prevent the signal from bouncing Break in cable brings down entire bus
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Bus LAN Diagram
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LAN Topologies: Tree
Generalization of bus topology Branching cable with no closed loops Cable(s) begin at headend, travel to
branches which may have branches of their own
Each transmission propagates through network, can be received by any station
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LAN Topologies: Ring
Repeaters are joined by unidirectional point-to-point links in a ring
As data circulates past a receiver, the receiver checks its address, and copies those intended for it into a local buffer
Data circulates until it returns to source, which removes it from network
Better performance at high levels of usage
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Ring LAN Diagram
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LAN Topologies: Star
Each station connected point-to-point to a central station, usually with two undirectional links
Switching in the central station connects pairs of nodes together
Central node can broadcast info, or can switch frames among stations
Failure of central station causes entire network to go down
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Star LAN Diagram
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Ethernet MAC Protocol
MAC – Medium Access Control Ethernet and CSMA/CD
Carrier sense multiple access with collision detection
Four step procedure If medium is idle, transmit If medium is busy, listen until idle and then transmit If collision is detected, cease transmitting After a collision, wait a random amount of time
before retransmitting
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Ethernet Frame
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Switched Ethernet
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Token Ring MAC Protocol
Token “seized” by changing a bit on the circulating frame to indicate start of frame rather than token
Default configuration requires sender to complete transmission and begin receiving transmitted frame before releasing the token
“Early token release” allows release of token after transmission but before receipt of frame
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Hubs
The active central element of the star layout.
When a single station transmits, the hub repeats the signal on the outgoing line to each station.
Hubs can be cascaded in a hierarchical configuration
Ethernet hubs are physically a star but logically a bus.
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Bridges
Allow connections between LANs and to WANs
Used between similar networks Read all frames from each network Accept frames from sender on one network
that are addressed to a receiver on the other network
Retransmit frames from sender using MAC protocol for receiver
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Routers
Similar to bridges but connect dissimilar networks
Convert format of the message to correspond to the protocol of the other network
Network traffic is specifically addressed to the router
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Wide Area Network Circuit switching
Dedicated channel between source and destination for duration of connection
Message switching Dedicated channel for an entire message
Packet switching An independent path is created for each datagram
Virtual circuit switching A route is created from source to destination
before transmission begins and all datagrams are sent using the same route
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Networks vs. Clusters
Externally, clusters appear as a single computing unit.
Network nodes are individually identifiable.
Workload on a cluster is determined by cluster administration and load-balancing software.
Network workload cannot be controlled using the above method.
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High Performance Computing
Massively parallel processor architectures (MPP)
Clusters of power machines or larger Beowulf blade clusters Well suited for problems that can be broken into
subtasks
Grid computing Supercomputer performance through distributing
CPU processing to the spare CPU cycles of personal computers connected to a network
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Parallel Computers
Massively parallel architectures Hundreds to millions of CPUs CPUs have small amounts of local memory All CPUs have access to global shared
memory Pipelined CPUs
Results from one CPU flow to the next CPU for additional processing
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Copyright 2003 John Wiley & Sons
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