- What are SONET and T1
- The Development of SONET
- Role of ANSI and Key Standards documents
- The Network and Services Integration Forum (NSIF)
- SONET and T1
- Features of SONET and T1
- Synchronous Networks
- SONET Timing
- Payloads and Envelopes
- Optical Fiber—The Bedrock for SONET
- Typical SONET Topology
- Present Transport Systems and SONET
- Clarification of Terms
Present Transport Systems and SONET
The present digital transport carrier system varies in the different geographical regions of the world. The structure is different in Japan than it is in North America, which is itself different than the structure in Europe. This disparate approach is complex and makes the interworking of the systems difficult and expensive. Moreover, it means that companies that build hardware and software for carrier systems must implement multiple commercial platforms for what could be one technology.
While SONET does not ensure equipment compatibility, it does provide a basis for vendors to build worldwide standards. Moreover, as shown with the shaded area in Figure 15, SONET is backwards compatible, in that it supports the current transport carriers' asynchronous systems in North America, Europe, and Japan. This feature is quite important because it allows different digital signals and hierarchies to operate with a common transport system, SONET. By the way, don't be concerned with all the details shown in Figure 15; they are explained later.
Figure 15 SONET support for current technologies. Note: Unless noted otherwise, speeds in Mbit/s.