Optical Internetworking Forum debuts very short reach interface

Jan. 15, 2001
The Optical Internetworking Forum (OIF) announced the adoption of two Very Short Reach (VSR) OC-192 interface Implementation Agreements.

The Optical Internetworking Forum (OIF) announced the adoption of two Very Short Reach (VSR) OC-192 interface Implementation Agreements. These VSR interfaces are intended to help reduce the cost of OC-192/STM-64 links between equipment in a single central office (CO). The first specification, OIF-VSR-01.0 (VSR-1) is titled Very Short Reach (VSR) OC-192 Interface Based on Parallel Optics. VSR-1 has 12 fibers at 1.25Gbit/s each, uses 62.5µm-core multi-mode ribbon fiber and reaches up to 300 meters. The second specification, OIF-VSR-02.0 (VSR-2) is titled Serial OC-192 1310 nanometer Very Short Reach (VSR) Interfaces. VSR-2 uses single mode fiber (SMF) and reaches up to 600 meters.

VSR-1 and VSR-2 are complementary. VSR-1 uses lower speed signals and has the potential to be the lowest cost OC-192 link. It is particularly suitable for the shortest reaches, where the ribbon fiber can be treated like any ordinary patch cable. VSR-2 uses installed SMF and can reach across very large COs. The OC-192 VSR interfaces interconnect co-located equipment such as routers, Dense Wavelength Division Multiplexers (DWDM), optical cross-connects, and SONET/SDH Add-Drop Multiplexers (ADMs) within a CO.

VSR-1: Very Short Reach (VSR) OC-192 Interface Based on Parallel Optics

VSR-1 adapts high-volume Gigabit Ethernet technology in the form of 1.25Gbit/s signaling with 850 nanometer lasers over multi-mode fiber. VSR-1 uses 12 of these channels over ribbon fiber and reaches up to 300 meters. The 12 lasers can be implemented with a single Vertical Cavity Surface Emitting Laser (VCSEL) array. 10 of the fibers carry data, one carries CRC error detection codes, and the 12th fiber carries parity of the 10 data fibers. This enables hitless correction of errors on any single fiber, including the loss of a fiber. Field termination of the multi-mode ribbon fiber is supported. The link electronics automatically adapt to either ribbon orientation, so there is no such thing as a twisted ribbon or a connector put on upside down.

The components required to implement VSR-1 are now available from suppliers, and OIF members have demonstrated multi-vendor interoperability of the interface.

VSR-2: Serial OC-192 1310 nanometer Very Short Reach (VSR) Interfaces

VSR-2 is based on ITU G.691. It uses 10Gbit/s serial signaling with a 1310 nanometer laser over SMF and reaches up to 600 meters. Compared to SONET Short Reach (SR) interfaces, it relaxes some optical parameters. It allows increased dispersion and reduced reach with the intent of enabling lower cost devices.

About the OIF Physical & Link Layer Working Group

The OIF Physical and Link Layer (PLL) Working Group creates Implementation Agreements (IAs) for critical interfaces between and within optical internetworking equipment. This helps increase interoperability and reduce costs. Last year, the OIF PLL created IAs for the interfaces on both sides of OC-192 framers. It recently began work on OC-768 VSR and framer interfaces.

About the OIF:

Launched in April of 1998, the OIF, a non-profit organization, unites packet and voice networks, helps advance the standards and methods of optical networks, and fosters the development and deployment of interoperable products and services for data switching and routing using optical networking technologies.