PDF of this tutorialMMAP Concept
A new concept—one that strikes at the heart of the carrier's dilemma—is now emerging with the introduction of the MMAP approach. The MMAP concept combines in a single platform the functions of an optical multiplexer with a multiple-service access device and adds to that the capability to support multiple additional functions, such as a GR–303/V5.2 gateway or T3/E3 aggregation.
This new approach uses a rack-mounted chassis that serves as the foundation for the MMAP. A wide variety of interface and function cards can be inserted into the MMAP chassis to tailor the platform to specific roles.
Figure 2. MMAP–Based Local Access and MAN
Figure 2 shows an MMAP application in a carrier network. Note how the optical interface function to the MAN has been combined with a multiplicity of different access interfaces. All of this has been subsumed into one platform and positioned strategically at the boundary between the optical MAN and the local access networks.
The high-speed optical uplink function of the MMAP provides the interface to the optical MAN. The optical uplink functionality is contained on interface cards that can be inserted into the MMAP chassis as required. This modular, card-based approach means that the MMAP can be easily configured to the requirements of the MAN to which it will be connected. It also provides an easy upgrade path in the event that increased transport speeds are required because of additional service demand.
There is already a move underway to offer multiple-service access platforms. Such devices integrate two or more access facility types into one device. What truly sets an MMAP apart from these is the high-density integration of all (or substantially all) of the access types that a carrier may reasonably be expected to support and the incorporation of multiple other functions into a single platform that effectively bridges the access network to the MAN. The MMAP can interface to any part of the MAN or be located directly on the MAN as appropriate.
Driving Forces for Migration to MMAPs
Local carriers face a variety of challenges. At the top level, there is the ever-accelerating need to limit capital investment and improve the profitability. Therefore, a number of issues are high on the priority list.
The financial markets have become much more reluctant to provide fresh capital to telcom operators. For a number of operators, it is practically impossible to get new access to capital in the short term. Therefore, investment budgets are limited, and money should be spent on projects that generate immediate revenue. Building a network with the service-specific approach requires high up-front investment costs. For example, a complete DSLAM chassis has to be installed and connected to the backbone before the first customer can be connected. This scenario is repeated for each new service. An MMAP dramatically reduces the up-front investment costs. Only one chassis is required to offer all available services. This results in a much more modular network buildout. Line cards and modules are added when customers order the service, thereby immediately starting to generate revenue.
Building out the MAN based on ATM over SONET results in significant savings of bandwidth. It has been shown that ATM over SONET in mixed voice/data applications reduces the required bandwidth in the MAN with a factor of 2 to 4, depending on the application scenario. This allows the carrier to use lower-speed optical equipment such as OC–12c instead of OC–48c and OC–48c instead of OC–192. It is especially the very high-speed SONET equipment that is still very expensive.
Another important aspect is the limitation on rack space. For co-location applications, rack space is very limited and therefore expensive. When more rack space is required, operating costs increase due to increased rent, energy charges, cooling charges, etc. The use of an MMAP significantly reduces the required rack space. Deployment can take off with one MMAP shelf, delivering all the services. Only when one shelf is fully populated, thereby revenue-generating, is a new shelf required.
Another driving force for MMAP is the reduction of the operational complexity of managing disparate service-specific systems. MMAPs allow the management of the whole access and metropolitan network through a single management system. The operational benefits include less training of staff, unified alarm reporting, and a single, unified provisioning system.
