Optical/IP Networks

OIF Specs Component Standard

The Optical Internetworking Forum this week released a set of specs that it claims will streamline the manufacture of high-speed routers and switches with Sonet optical interfaces. The group is also about to release a new short-reach Sonet interface to link the same devices to DWDM (dense wavelength-division multiplexing) gear inside central offices.

The documents released define a way for electrical chips to communicate with Sonet framer chips inside routers, switches, and crossconnects. The specs describe the exchange of packet and cell-based traffic between a device's system chips and Sonet components supporting OC48 (2.5 Gbit/s) and OC192 (10 Gbit/s) data rates.

All of this, the OIF says, will let component suppliers manufacture standardized parts using mass-production techniques, instead of reinventing the wheel each time a new part is needed. Also, it will give equipment vendors a choice of suppliers for key components. Both things could eventually prompt a drop in the cost of next-gen routing and switching equipment.

"We haven't established a number yet, but there's certainly a serious cost associated with having only one source for all your components," says Russ Tuck, chair of the OIF's Physical and Link Layer Working Group, which defined this set of specs. Tuck is also a systems architect at IP router vendor Pluris Inc.

The OIF specs also aim to simplify life for carriers, by providing the basis for another OIF project, namely, creating a very short-reach interface that allows cheaper components to be used for linking equipment inside a central office at distances under 1 kilometer.

Sounds familiar: Isn't this just what the The Institute of Electrical and Electronics Engineers Inc. (IEEE) has been trying to achieve? The IEEE is also aiming to create short-reach interfaces for carriers' use inside central offices, although these will be based on Ethernet, not Sonet (see IEEE Nails Down 10-Gig Ethernet Basics). OIF spokespeople acknowledge there may be some overlap in the short-reach interface. Today, carriers are using a variety of pricey high-speed interfaces to link gear in central offices. These range from gigabit Ethernet to Fibre Channel. Some also are using full-scale Sonet to link routers to WDM gear.

The new interface, the OIF says, is aimed specifically at making these short Sonet links as cheap as Ethernet -- perhaps ten times cheaper than today. The specs will be released within a few weeks, spokespeople say.

And overlap will have to be sorted out in the field. "Standards are evolving that will allow Ethernet to travel long distances and Sonet to travel short ones," says Russ Tuck. "There's going to be some overlap initially, as carriers decide the cost benefits of each application."

-- Mary Jander, senior editor, Light Reading http://www.lightreading.com

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