NoC(Network on a Chip) is a method of placing a much larger number of processors on a multi-core chip. Rather than communicating through shared memory as multi-core processors do, each core or module on a NoC chip has a network interface. The modules determine which unit can access the network by the routing header.
When a large number of processor cores and other modules are placed on a chip, communicating through a network actually reduces the complexity and provides better speed and reliability. Power efficiency of an NoC system is also improved compared to other multi-core designs.
Much like a regular network, NoC has multiple point-to-point data links that are interconnected by routing switches. Having a network for communication allows easier troubleshooting and defective cores or modules can be eliminated by making decisions at routing switches.