2.1 CT Access Switching Service

2.2 Characteristics

2.2.1 Switch Handles

2.2.2 Terminus

2.2.3 MVIP-95 Switch Block Model

2.3 Switching Service Functionality

2.1 CT Access Switching Service

The CT Access Switching service:

• Provides a set of functions for controlling Multi-Vendor Integration Protocol (MVIP) switch blocks on MVIP and H.100/H.110 compliant switching devices. The switch block is controlled by the Switching service functions to make or break connections, send patterns, sample data, query, reset, configure, and run diagnostics on different parts of the MVIP switching device.

• Is based on the MVIP-95 and CT Bus device driver standards. It can be used to access MVIP-95 and MVIP-90 device drivers.

2.2 Characteristics

You need to understand the following characteristics of the CT Access Switching service as you prepare to create an application:

• Switch handles

• Terminus

• MVIP-95 switch block model

2.2.1 Switch Handles

Many functions take (or return) a switch handle. A switch handle identifies an open MVIP switching device.

To access an MVIP switching device, get a switch handle by calling swiOpenSwitch. Refer to Section 3.2, Opening a Switch Handle.

swiCloseSwitch releases a switch handle. Refer to Section 3.3, Closing a Switch Handle.

2.2.2 Terminus

A terminus is a single access point to a switch block input or switch block output. Many of the Switching service functions take one or more terminus elements as an argument.

A terminus contains a bus, a stream, and a timeslot:

Component	Description
Bus	Specifies the interface point of the switch block. Devices can reside directly on the telephony bus. Devices can also reside on a board's local bus and may require a switch block to access the telephony bus.
Stream	Specifies a grouping of timeslots that usually corresponds to a particular bit-stream of time-division multiplexed (TDM) serial data on an individual track or wire of a bus.
Timeslot	Specifies a particular 64 kbit/second subdivision of a TDM bus stream. Timeslots number from zero (0) to n, where n is stream-dependent.

2.2.3 MVIP-95 Switch Block Model

The H.100/H.110 bus has 32 data streams. The MVIP-95 switch model was created to accommodate the complete set of streams (0 to 31).

The MVIP-95 switch model is used with H.100/H.110 busses. The MVIP-95 model is based on the premise that a given stream number corresponds to the same physical wire on both sides of the switch block.

As illustrated in Figure 2, MVIP-95 uses one number for each bus signal, regardless of the side of the switch block. In MVIP-95, bus signals are numbered sequentially starting at 0. This allows for future expansion of the switch capacity without renumbering.

Figure 2. H.100/H.110 Switch Block Model

In MVIP-95, local devices are connected to a logical bus called a local bus. The streams they are connected to (MVIP and local) are numbered sequentially starting from 0 on the local bus. Therefore, there is a need to explicitly specify the bus when referring to a switch block input or output. MVIP-95 defines a new data structure called a terminus that contains a bus specifier, a stream number, and a timeslot number to refer to a switch block input and output.

For more information about the switch block models, refer to Getting Started With MVIP Switching.

2.3 Switching Service Functionality

The CT Access Switching service contains the following functionality:

• Opening and closing a switch handle

• Configuring the clock

• Setting up switching

• Configuring stream speed

• Configuring boards and drivers

• Verifying switching operations

• Calling the MVIP device driver