Wednesday, April 15, 2015

Network on Chip and Its Topologies

Network on chip is a communication subsystem on a chip. NoC is the blend of network theory and methods for the communication on the chip. Mainly NoC is used in large VLSI systems for communication purposes. Public transportation Network is used for the transfer of information between various blocks in the network.

NoC is constructed by the combinations of the various Routers and Router play the most important role in the communication of the Network. The main message is delivering to the destination from the generating source by the help of the routers.

Router:

Router provides the Route for transferring the data from one block to block. It provides the exact controls to the Router so these controls can transfer the message or data.

Advantages of NoC:

There are many advantages of NoC. Some of them given below:

i)          The Communication channel of big design on single chip was very complex but by the help of the NoC it becomes easy to understand.
ii)           Reduction in physical area.

Parameters used to Measure the NoC performance:
  1.       Throughput 
  2.       Bandwidth
  3.       Latency
Throughput is the maximum traffic accepted by the network. 

The bandwidth refers to the maximum rate of data propagation. The measurement unit of bandwidth is bits per second.

Latency is the time among the beginning of the transmission of the data and its complete reception at the destination.

Various Topologies used in NoC:

Here Topology word is used to tell the type of the connection between the different routers.

i)                    2-D Grid:
The main connection for the Routers in the 2-D Grid Topology is shown in the below given diagram:

                         
                                                          2-D Grid Topology network

ii)                  2-D Torus:

There are connected various Routers in the following figure.


                                  
2-D Torus Topology Connection

iii)                3-D Hypercube:

The routers connection for the 3-D hypercube topology is shown below:

  
                             
                                     3-D Hypercube Topology Connection

iv)                Octagon:

The connection for the octagon topology is shown below. In this, routers are connected in the octagon pattern so called as the octagon topology.


                                  
                                       Octagon topology connection

v)                  Fat tree :

The connection of the Router for the Fat tree topology is shown below. This type of topology connection is indirect one.

Fat Tree

vi)                3-stage butterfly:

The connection for the 3 stage butterfly topology is shown below:


                            
                                                    3-Stage Butterfly topology connection