PDF of this tutorialOADX As Alternative to OADM for Scaling Capacity in Core Metro Networks (e.g., Inter-Office Facility)
SONET/SDH rings are the predominant architecture in the metro core today. While the reliability of SONET/SDH rings is well regarded, network operators are starting to see many issues with SONET/SDH technology as the transport networking architecture for their evolving metro networks. Due to dramatic rise in bandwidth demand and diversity of traffic types (i.e., less friendly to SONET/SDH payloads), more and more network operators are looking at evolving their metro networks to an optical transparent wavelength networking infrastructure.
Today, one option to provide an optical transparent wavelength infrastructure in the metro is to use the classical OADM device for transport and a fiber patch-panel (FPP) for wavelength switching. Note, a photonic switch could be used for transparent wavelength switching, but these devices are not yet commercially available and will be an expensive proposition for the metro for some time. The OADM and FPP architecture has two significant drawbacks:
- No dynamic reconfiguration of wavelengths
- OADMs are restricted to ring and point-to-point topologies
An attractive alternative to the OADM/FPP for evolving the metro interoffice facility (IOF) is the OADX. The OADX with its inherent transparent wavelength switching capabilities will provide a full dynamic wavelength networking solution that can be deployed in a ring or mesh structure. A metro IOF network can be deployed initially as a ring to match the existing fiber plant or to minimize the start-up cost. At any future date, the ring can be upgraded to a partial or full mesh without affecting service to existing customers.
Offloading Broadband Digital Cross-Connect
Broadband digital cross-connects (DCSs) play an important role in the network because they groom traffic down to the synchronous transport signal (STS)–1 level and aggregate the traffic for more efficient transport. The OADX can be used to supplement the broadband DCS, offloading expensive ports used for wavelengths. Combining OADXs with STS–1 groomers is a very economical application for telecommunications carriers.
