Transfer data between processors and to/from memory.
Made of switches and links.
Can be static or dynamic, direct and indirect.
Static networks are made or direct connections (point-to-point)
between nodes.
Dynamic networks use switches to find optimal paths between nodes.
Can be centralized, decentralized, and distributed.
Parallel Networks Topologies
Physical or logical. It affects how the communication between
processes happens.
Ring or linear (chain)
Star
Mesh
Balanced binary tree
Hypercube
Torus, butterfly, dragonfly
Network Properties
Diameter: the diameter of a network with n nodes is the
length of the maximum shortest path between any two nodes in the
network.
Degree of a node: the number of connections for that node.
Latency: total time to send a message.
Bandwidth: number of bits transmitted in a unit of time.
Bisection: the number of connections that need to be cut
to partition the network in 2.
More on Topologies
Star
topology - a central computer or switch (hub), all the
others are connected to it. Logical: master-slave model.
One rim computer failing doesn't bring the network down, but the
hub failing does.
Ring topology - every process is connected to two others.
Mesh topology - every process has multiple
neighbors. Provides link redundancies in case of failures. Can be full
or partial.
Full mesh
Partial mesh
Complete Binary Tree
There is only one path between any two nodes.
Bottlenecks can happen at the top nodes. One can increase the
number of switches at the top
Dynamic trees: leaf nodes for processing and intermediate ones as
switches.
Diameter: 2*log(n)
Hypercube
Starting with a hypercube of dimension n-1, add an extra bit to
the node labels, then create a connection from each 0xxx node to the
matching 1xxx node.
