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INTERCONNECTION NETWORKS

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INTERCONNECTION NETWORKS Work done as part of Parallel Architecture Under the guidance of Dr. Edwin Sha By Gomathy Gowri Narayanan Karthik Alagu Dynamic Interconnection – PowerPoint PPT presentation

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Title: INTERCONNECTION NETWORKS


1
INTERCONNECTION NETWORKS
  • Work done as part of
  • Parallel Architecture
  • Under the guidance of
  • Dr. Edwin Sha
  • By
  • Gomathy Gowri Narayanan
  • Karthik Alagu

Dynamic Interconnection Networks -
Gomathy
Interconnection Networks
-Karthik
2
ORGANISATION OF THE PRESENTATION
  • Study Interconnection Networks
  • Requirements
  • Network Design Considerations
  • Static Interconnection Networks
  • Dynamic Interconnection Networks
  • Concentrate more on the DIN and on MIN
  • Comparisons and Tradeoffs

3
What are Interconnection Networks?
  • Connect processors and memory banks
  • Determines the overall performance
  • Consists of Processing Elements
  • Route packets based on application

4
Interconnection Networks
  • Processing element to processing element
  • N processing elements connected by network.
  • Processing element(PE) ? own processor and
    elements.
  • Unidirectional network.
  • Processor to memory
  • Position network between processors and memories
  • Bidirectional
  • Connects each processor to all or some subset of
    memories
  • Move data from processor to processor ? thro
    memories

5
Requirements
  • Transfer a maximum number of messages in minimum
    time with minimum cost and maximal reliability.
  • Small diameter and small average distance
  • Small and fixed vertex degree
  • Large bisection width
  • High connectivity and fault tolerance
  • Small fault average distance and diameter
  • Hamiltonianity
  • Hierarchical recursivity
  • Incremental extendibility and incremental
    scalability
  • Symmetry
  • Support for routing and collective communication

6
Design Considerations
  • Performance requirements
  • Message latency
  • network may saturate
  • throughput
  • Scalability
  • Incremental expandability
  • Distance span
  • Physical constraints
  • Reliability
  • Expected workloads
  • Control strategy
  • Switching methodology
  • Cost constraints

7
Metrics
  • Framework to compare and evaluate interconnection
    networks.
  • Network connectivity ? measures resilience and
    fault tolerance
  • Network diameter ? maximum inter-node distance
  • Narrowness ? congestion in a network
  • Network expansion increments ? expandability

8
Classification
  • Topology ? what type of network
  • Direct/indirect
  • Switching strategy ? how data in a message
    traverses a route.
  • Circuit switching/packet switching
  • Routing algorithm ? which path the data follows
  • Deterministic
  • Adaptive
  • Store and forward
  • Cut-through switching Worm-hole routing
  • Flow control mechanism ? when a message traverses
    a route
  • Ethernet, FDDI/token ring, TCP/WAN

9
Static interconnection networks
  • Topology remains same
  • Connected statically via Point-Point
    communication links
  • Used in message-passing architectures

10
Static interconnection networks
  • Completely-connected network.
  • Star-connected network.
  • Linear array or ring of processors.
  • Mesh network (in 2- or 3D).
  • Intel Paragon XP/S, Cray T3D/E
  • Tree network of processors.
  • TMC CM5
  • Hypercube network.
  • SGI/Cray Origin 2000

11
Dynamic interconnection networks
  • Connected dynamically via switches or buses
  • Allow reconfiguration during operation
  • Used in shared address space architectures
  • Cost number of switch boxes required

12
Types
  • Bus-based networks
  • PE-M ? Common data path
  • Crossbar switching networks
  • grid of switching elements
  • Multistage interconnection networks
  • In multiprocessor systems
  • Compromise between cost and performance
  • Non-blocking
  • Rearrangeable
  • Blocking
  • Multilevel interconnection network
  • two or more levels of connections
  • SGI/Cray Origin 2000

13
Detailed overview
  • Bus Architecture
  • Used over a wide range of cost and performance
  • Limitations
  • capacity bottleneck
  • single point of failure
  • Limited Fan out capability
  • Solution use multiple shared buses.
  • Sequent symmetry and Alliant(double)

14
  • Cross Bar Networks
  • non-blocking access from any input port to any
    output port
  • Low latency
  • Problems
  • requires O (N2)
  • number of pins
  • Ex C - YMP and Fujitsu VPP 500

15
Multistage Interconnection Networks
  • Sets of switches in parallel
  • Nodes are switches
  • Types of MIN
  • Omega
  • Generalized cube
  • Clos
  • Benes
  • Banyan
  • Butterfly
  • Gemini
  • Honeycomb
  • Delta
  • Bi-delta

16
Omega network
  • Multistage implementation of single-stage
    shuffle-exchange network.
  • 4 operations ?
  • Blocking
  • routes to different memory banks share a link -
    message blocked
  • log p stages
  • Broadcast data to multiple destinations

17
Generalized-cube networks
  • Multistage cube-type network topology
  • log2N stages.

18
Clos network
  • Rearrangable non-blocking
  • Implements low latency, high-bandwidth,
    connection-oriented ATM switching.
  • Multiple routes between hosts
  • ? deadlock-free hot-spots
  • No. of middle switches (2n-1)i

19
Benes Networks
  • Special case of Clos networks made of 2 x 2
    switches
  • Recursively constructed from Clos network
  • Exhibits a symmetric topological structure.
  • Minimal number of cross points
  • For N x N switches
  • N/2 alternative paths
  • 2 log N-1 stages
  • cost N2

20
Banyan network
  • Unique path from each input to each output
  • For k k switches
  • logk N stages
  • N/k logk N switches
  • Advantages
  • self-routing
  • regularity and interconnection patterns
  • makes very attractive for VLSI implementation
  • Blocking - buffers

21
Butterfly networks
  • Built using crossbar switches
  • closely related to shuffle-exchange networks
  • no broadcast connections
  • Unique path of length log N
  • Source Oblivious path selection
  • NYU Ultra computer, IBM RP3, BBN Butterfly, NEC's
    Cenju

22
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23
Gemini Networks
  • Dual technology interconnection network
  • Used in tightly coupled multicomputer systems.
  • circuit-switched optical data path in parallel
    with a packet-switched electrical control/data
    path.
  • optical path ? transmission of long data messages
  • electrical path ? switch control and transmission
    of short messages.
  • O (N log N) switching elements

24
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25
Honey Comb network
  • Based on hexagonal plane tessellation
  • n nodes
  • degree 3
  • Diameter O ( sqrt (n))
  • Network cost degree diameter
  • Easy physical layout

26
Delta Networks
  • Digit controlled or baseline routing
  • recursive structure
  • Path descriptor
  • Exactly one path from each input node to each
    output node.

27
Comparison of DIN
  • Bus based
  • Increasing processor, performance deteriorate
  • Crossbar
  • Good data performance - expensive
  • Multistage
  • Compensate between cost and performance

28
Tradeoffs
29
Comparison of MIN
30
Real machines
31
Summary
  • Interconnection Overview
  • Static Interconnection Networks
  • Dynamic Interconnection Networks
  • Multistage Interconnection Networks
  • Tradeoffs
  • Comparisons
  • Comment choice of IN depends on the application

32
Questions ??
33
  • Our thanks to
  • Dr. Edwin Sha
  • for his support and guidance.
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