Cisco Cisco ONS 15454 SONET Multiservice Provisioning Platform (MSPP) Guía De Diseño

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SONET TDM takes synchronous and asynchronous signals and multiplexes them to a single 
higher bit rate for transmission at a single wavelength over fiber.  Source signals may have to be 
converted from electrical to optical, or from optical to electrical and back to optical before being 
multiplexed.  WDM takes multiple optical signals, maps them to individual wavelengths, and 
multiplexes the wavelengths over a single fiber. Another fundamental difference between the two 
technologies is that WDM can carry multiple protocols without a common signal format, while 
SONET cannot.  Some of the key differences between TDM and WDM interfaces are graphically 
illustrated in Figure C-1. 
 

 

 

Bandwidth, the chief driver in the long-haul market, is also a big driver in metropolitan area, 
access, and large enterprise networks.  In these types of networks additional applications driving 
demand for bandwidth include storage area networks (SANs), which make possible the 
serverless office, consolidation of data centers, and real-time transaction processing backup. 
 

 
DWDM has been very successful in the backbone.  It was first deployed on long-haul routes in a 
time of fiber scarcity.  Then the equipment savings made it the solution of choice for new long-
haul routes, even when ample fiber was available.  While DWDM can relieve fiber exhaust in the 
metropolitan area, its value in this market extends beyond this single advantage.  Alternatives for 
capacity enhancement exist, such as pulling new cable and SONET overlays, but DWDM can do 
more.  What delivers additional value in the metropolitan market is DWDM’s fast and flexible 
provisioning of protocol- and bit rate-transparent, data-centric, protected services, along with the 
ability to offer new and higher-speed services at less cost. 
 
The need to provision services of varying types in a rapid and efficient manner in response to the 
changing demands of customers is a distinguishing characteristic of the metropolitan networks.  
With SONET, which is the foundation of the vast majority of existing MANs, service provisioning 
is a lengthy and complex process. Network planning and analysis, ADM provisioning, Digital 
Cross-connect System (DCS) reconfiguration, path and circuit verification, and service creation 
can take several weeks.  By contrast, with DWDM equipment in place provisioning new service 
can be as simple as turning on another lightwave in an existing fiber pair.