Photonic Burst Switching, Key Fabric to AcceLight's Photonic Service Switching

ANAHEIM, Calif., July 1 -- AcceLight Networks Inc. claims to have eclipsed Moore's law with a new type of intelligent core networking called Photonic Service Switching (PSS). This type of switching consolidates multiple network layers to one intelligent optical core platform. The company demonstrated its breakthrough technology at invitation-only sessions during OFC 2001 in Anaheim, Calif. This article gives some facts behind the key fabric of PSS, which is photonics burst switching (PBS).

AcceLight's Patented PBS Technology

The basis of AcceLight Networks' photonic service switching solution is its patented photonics burst switching (PBS). Using a solid-state wafer-scale optical device that switches wavelengths in nanoseconds, PBS is the core of AcceLight Networks' PSS-based switch. To deliver exponential scalability, PBS enables switch fabric reconfiguration cycles in nanoseconds with scheduling and synchronization between the line cards. This allows multiple traffic types to be multiplexed and switched simultaneously. The traffic sources are referred to as TOPS: TDM + Optical + Packets.

Benefits of PBS

Unprecedented scalability. AcceLight's PBS technology -- with its capability to scale in three dimensions simultaneously -- speed, density, and wavelengths -- enables the implementation of the photonic service switch to achieve massive scalability.
    Port density is achieved at both the line card interfaces and fabric density. The scheduling algorithm between the fabric and line cards is proven to several thousand interfaces.
    Scalability in port speed. The bit rate independent nature of photonic switching makes every fabric port on the PBS fabric scalable to 40 G/s and beyond.
    Scalability to support transparent wavelength switching. PBS is wavelength and polarization independent. This allows virtually limitless switching throughput.

PBS Operates in Various Modes

Our PBS fabric reconfigures in nanoseconds -- 100,000 times faster than any other optical switching technology on the market. This enables photonics service switching to operate in various modes:

A PBS fabric can operate in circuit-switched mode and perform as a photonic cross-connect
A PBS fabric can operate in burst mode to transfer asynchronous or synchronous bursts of optical signals from input to output ports -- combined with fast scheduling. Such a switch can operate as a packet switch transferring bursts of optical signals.
A PBS fabric can operate in hybrid mode by combining aspects of the previously mentioned circuit and packet transfers.

A PBS fabric operating in either "burst" or "hybrid" mode can support this integrated network element. Dramatic simplification results from the action of intra-POP interfaces and the introduction of a single common control and managements framework.

Enabling TOPS

By combining the appropriate line card with sufficiently fast scheduling, a PSS can operate with a PBS to function as a consolidated optical switching fabric for all types of traffic from packet, TDM and wavelength services.
    For multishelf systems, PBS-based switching systems reduce the number of Optical to Electronic to Optical (O-E-O) conversions by completely eliminating the O-E-O stage. This simplified network architecture translates into real cost savings for service providers.
    With PBS, the fabric is kept simple. It is the line card density that can grow. When combined with service-specific line cards AcceLight's PBS fabric can operate in various modes and intelligently switch any type of traffic with equal speed and efficiency.
    Integrated with the G-MPLS-based control plane and supported by an intelligent fabric scheduling algorithm, PBS ensures programmable Quality of Service (QoS) levels for various traffic flows, while enforcing protection and restoration policies for different service types.

From PBS to Photonic Service Switching

In today's carrier-class networks the core network provides transport services, which include TDM circuits, IP/MPLS label switched paths and optical paths. These services are made available through service-specific interfaces. Multiple interconnected network elements in the POP are needed to provide the appropriate path across the network. PBS enables the PSS to support the TOPS traffic, which consolidates several network elements in the PSS.

Setting new Standards for Network Scalability, Reliability and Speed

PBS-based switches are built using solid-state technology on a wafer-scale optical device. This technology plays an essential role in ensuring core network reliability and performance. In addition to achieving switching speeds several orders of magnitude higher than other technologies -- AcceLight's PBS surpasses the 99.999 percent minimum availability required by core grade, carrier-class networks.
Compared to other optical switching technologies based on MEMS, liquid crystal and bubble -- all of which carry some form of environmental sensitivity, the inherent nature of PBS-based switches makes them not vulnerable to environmental factors such as vibration, humidity and temperature variation.

AcceLight's Switching Solutions Add up to New Services and New Revenue

With the new efficiencies offered by PBS-based switching, service providers can not only maintain their established revenue-rich markets supported by legacy systems, but also exploit a wide range of new revenue generating services made possible by the massive scalability of AcceLight's Photonic Service Switching. New services could include:

Bandwidth brokerage
Mass bandwidth trading
Bandwidth trading
Commoditized bandwidth with a content-centric approach
Point and click provisioning--delivering bandwidth where and when it's needed
Packet plus circuit service bundling
Uniform enforceable Service Level Agreement