Isochronets: a High-Speed Network Switching Architecture

Contact: Danilo Florissi


Traditional network architectures present two main limitations when applied to High-Speed Networks (HSNs): they do not scale with link speeds and they do not adequately support the quality of service needs of high-performance applications. The novel Isochronets architecture overcomes both limitations.


Isochronets view frame motions over links in analogy to car motions on roads. In the latter, traffic lights coordinate contention at intersections. They can synchronize to create a green wave of uninterrupted motion. Isochronets accomplish similar uninterrupted motion by periodically configuring network switches to create end-end routes in the network. Frames flow along these enabled routes requiring no header processing at intermediate network switches.

The basic construct used to schedule traffic motion is a time band (green band) assigned to a routing tree. During the green band, a frame transmitted by a source will propagate down the routing tree to the destination (root of the tree). If no other traffic contends for the tree, it will move uninterrupted, as depicted by the straight time-line.

The green band in maintained by switching nodes through timers synchronized to reflect latency along tree links. Synchronization is per band size, which is large compared to frame transmission time. It can thus be accomplished trough relatively simple mechanisms. Furthermore, synchronization errors can be easily accommodated. Routing along a green band is accomplished by configuring the switches to route frames on incoming tree links to the appropriate output tree links for the duration of the band. A source sends frames by scheduling transmission to the green bands of its destination.

In similarity to circuit switch or burst switch networks, green bands allocate reserved network resources. However, the units to which resources are allocated are neither point-point connections, not traffic bursts, but routes. Routes represent long-lived entities, and thus processing and scheduling complexities can be resolved over time scale much longer than latency.

Scheduling transmissions to the green bands of the destination offers the basis for synchronization of the end-nodes to the network operation. Isochronets can be used to signal periphery nodes when destination becomes available, leading to a novel transfer mode, called Loosely-synchronous Transfer Mode (LTM). The same signals can propagate through protocols at any layer and enhance their functionality. The resulting Synchronous Protocol Stack (SPS) can support novel application with stringent synchronization requirements.

Isochronets offer several advantages:


The following is a list of the on-going research in Isochronets:

People in Isochronets

Selected Publications

An Overview of the Isochronets Architecture for High Speed Networks
Yechiam Yemini and Danilo Florissi

Isochronets: a high-speed network switching architecture
(Thesis), Danilo Florissi

Protocols for Loosely-synchronous Networks
Danilo Florissi and Yechiam Yemini

Isochronets: a high-speed network switching architecture
Yechiam Yemini and Danilo Florissi

[DCC Home Page]