Birds Eye View of Interconnection Networks Nanjing University

Birds Eye View of Interconnection Networks Nanjing University 2016 The Power of Topology The Effect of Network The Grace of Solution 1

Glimpse at Interconnection Networks 2

Seas for Networks Nanjing University 2016 A wide variety of direct interconnection networks have been proposed for, or used in, parallel computers They differ in topological, performance, robustness, and reliability attributes.

Classification: Static vs. Dynamic Nanjing University 2016 n Static or Direct è è n Ring Mesh Hypercube ……… 110 100 111 101 010 000 011 001 Dynamic or Indirect: è Bus, è Crossbar, è MIN P 1 P 2 P 3 M 1 M 2 M 3 4

Line, Ring and Fully Connected Nanjing University 2016 Linear Array: the simplest topology. Fully Connected: Direct connection between every pair of processors, Highest cost, Similar to crossbar in some properties. Ring: Each node in the ring is connected to only two other nodes. Chordal Ring: A compromise between Ring and Fully Connected Network. 5

Mesh and Torus Nanjing University 2016 Mesh Topology 2 D Torus 3 D Torus 2 D torus: Meshes with ``wraparound'' connections, e. g. the node at the top of the grid has an ``up'' link that connects to the node at the bottom of the grid (also left to right). 6

Hypercube Nanjing University 2016 7

Tree and Star Nanjing University 2016 Tree and Star 8

Fat Tree Nanjing University 2016 8 port four paths 4 port PE 1 PE 2 PE 3 PE 4 PE 5 PE 6 PE 7 PE 8 PE 9 PE 10 PE 11 PE 12 PE 13 PE 14 PE 15 PE 16 Note that a message going from PE 2 to PE 5 may choose any one of four paths from the lower left router to the one at the root. This means that all four PE's attached to the lower left router have a path available to them to reach another node. 9

Crossbar switch Nanjing University 2016 P 0 –> M 1 P 1 –> M 3 P 2 –> M 2 P 3 –> M 0 Crossbar switch N*N switches (N processors N memory modules). The switch configures itself dynamically to connect a processor to a memory module. No contention -- Supports N! permutations. Costly, hard to scale, wastes switches for most patterns. 10

Multistage Network : Omega Network Nanjing University 2016 p processors and log 2 p stages Each stage consists of a perfect shuffle 11

Multistage Network : Butterfly Nanjing University 2016 Butter. Fly Network 12