Routing in Turn-Prohibition Based Feed-Forward Networks

Abstract

Abstract. The application of queuing theory to communications systems often requires that the respective networks are of a feed-forward nature, that is they have to be free of cyclic dependencies. An effective way to ensure this property is to identify a certain set of critical turns and to prohibit their use. A turn is a concatenation of two adjacent, consecutive links. Unfortunately, current routing algorithms are usually not equipped to handle forbidden turns and the required extensions are nontriviaL We discuss the relevant issues for the example of the widely deployed Dijkstra algorithm. Then, we address the general case and introduce the Turnnet concept, which supports arbitrary combinations of routing algorithms with turn-prohibiting feed-forward mechanisms.

A Unified Approach to Mapping and Routing on a Network-on-Chip for Both Best-Effort and Guaranteed Service Traffic

“…are evaluated further. We use the turn net approach described in [50], as the original Dijkstra's algorithm cannot find least-cost paths on a turnprohibited network. The NI architecture requires a path to incorporate at least one physical channel c ∈ C R as flows cannot turn around inside an NI.…”

Transforming general networks into feed-forward by using turn-prohibition

“…The main idea is to break all the cycles in the network through the prohibition of carefully selected turns. Although routing protocols are usually not equipped to handle forbidden turns, protocols such as Turnnet [9] make it possible to transform an arbitrary network with no prohibited turns into a new one without prohibited turns, without raising the routing complexity in an unacceptable manner. This allows us to use arbitrary routing schemes.…”

Stability of FIFO networks under adversarial models: State of the art

“…Of course, it is necessary to take care to choose the turns that guarantee that the resulting topology will become FIFO-stable, while also preserving network connectivity. The routing of packets can be performed by using a routing protocol, such as Turnnet [45], which has been specially designed for such a type of network.…”