PDF of this tutorial- MTAU
- Exception switch
- Some-to-some cross-connect
- Any-to-any cross-connect
- MTAU
This architecture provides test access only and is not well suited for any other application. It is the least sophisticated and least expensive architecture.
The purpose of this type of cross-connect is to connect a test bus and an attached tester (which may be internal or external to the MTAU) to any given port, allowing the user to remotely access the port for test.
Figure 3. MTAU
Exception Switch
This architecture is an enhancement to the MTAU that provides a greater number of access buses to any given port. This design allows one to use a specific bus for test access and the remaining buses for fallback switching to equipment that is pre-wired to the bus. These products are generally more expensive than the MTAU.
The exception switch helps to postpone truck rolls. However, a site visit is still required to rewire or reconfigure the switch to the default, straight through connection configuration.
Figure 4. Exception Switch
Some-to-Some Cross-Connect
The some-to-some architecture is composed of several small any-to-any matrices that can switch to each other in a very limited fashion. An input of one small any-to-any matrix may be switched to the output of another small any-to-any matrix over a multipath bus between them. However, the limited number of these buses quickly introduces blocking, making the architecture ineffective for applications requiring nonblocking any-to-any connectivity.
This limitation makes the some-to-some architecture not much more effective at meeting specific cross-connect application needs than the exception switch mentioned above.
Figure 5. Some-to-Some Cross-Connect
Any-to-Any Cross-Connect
The any-to-any cross-connect is the most flexible product listed here. When designed correctly, it is nonblocking, transparent to signal protocol and levels (including POTS and its ring voltage), and can be used in all of the applications mentioned above plus some additional ones such as provisioning and migration.
- Provisioning is the ability to connect an already wired subscriber port to any desired equipment port in the case that the customers initially requested. This provides the ability to offer any alternative service without requiring a truck roll and the associated time required to complete the task.
- Migration is the ability to upgrade service to a customer to any given alternate enhanced service. The any-to-any architecture is the only one that can provide remote testing, provisioning, fallback, and migration on a permanent basis that does not require ongoing manual wiring maintenance.
Figure 6. Any-to-Any Cross-Connect
As described in the section on matrix types, the disadvantage of the any-to-any architecture is the large number of cross-points required to implement a nonblocking cross-connect.
Stepper motor cross-point technology is the most cost-effective way to implement the large number of cross-points required in a true nonblocking any-to-any cross-connect.
