The Optical Internetworking Forum (OIF) has approved the External Network to Network Interface (E-NNI) implementation agreement (IA). Like standards, IAs are based on a general industry consensus on a wide range of Internet functions. E-NNI defines the key requirements for the exchange of network topology and status information between control domains within an automatically switched optical network (ASON).
This allows for path computation across optical domains that are managed individually by generalized multiprotocol label switching (GMPLS) and other methods. E-NNI routing supports scalable routing and interoperability across a carrier’s multivendor optical network for services such as Ethernet transport and bandwidth on demand. The IA includes the results from multivendor interoperabiltiy testing performed from 2003 through 2005.
The OIF Software Working Group also has updated the Extensions for the Interface Management API Project IA 3.0 released in 2004. This project will support features added to Ethernet, Sonet, synchronous digital hieracrchy (SDH), and plesiochronous digital hierarchy (PDH) by the more recent standards work in IEEE, ITU-T, MEF, and OPTXS. These extensions to the APIs should let system vendors develop and interface control functions for Ethernet services, GFP, VCAT, LCAS, and protection switching.
Another OIF project, focused on 40-Gbit/s optical signaling work, will be completed in conjunction with the ITU-T. It will study 40-Gbit/s modulation techniques suitable for the transport of OC-768/STM-256/OTU3 over higher dispersion links including longer transmission distances and operation without dispersion compensation.
Most 40-Gbit/s interfaces are sub-2-km on single-mode fiber (SMF). Common NRZ or on-off keying (OOK) data transmission formats can tolerate an accumulated dispersion of about 40 ps/nm over SMF before dispersion compensation is required. Alternate modulation techniques such as DuoBinary modulation or differential quadrature phase-shift keying (DQPSK) seem to offer better dispersion-tolerant performance in the popular 1550-nm range.
There are no defined interoperable optical interfaces for 40-Gbit/s serial data transmission for links with greater than 200 ps/nm of accumulated dispersion, which corresponds to a transmission distance of 10 km over SMF without dispersion compensation. This project will study the different modulation options and provide a recommendation for adoption in formal standards by the ITU-T.
More details on all of these projects are available on the OIF Web site.
Optical Internetworking Forum
www.oiforum.com