(Page 1 of 1 in this chapter)

Chapter 5

AG Connect Switching

5.1 Introduction
5.2 AG Connect MVIP Switch Models
5.2.1 AG Connect MVIP Switch Model (MVIP-90)
5.2.2 AG Connect MVIP Switch Model (MVIP-95)
5.3 Hybrids and Timeslots on the Local Bus
5.4 FMIC Switching Restrictions
5.4.1 Practical Outcomes of the FMIC Limitation
5.5 MVIP Clocking
5.6 Conferencing

5.1 Introduction

AG Connect boards are MVIP-90-compliant boards. They can be connected to the MVIP-90 telephony bus to share data and functionality with other boards connected to the same bus.This chapter describes how to use MVIP switching with AG Connect boards. This chapter is presented assuming a basic knowledge of time-division-multiplexing architecture using streams and timeslots. For more information about switching and time-division-multiplexing, refer to Getting Started With MVIP Switching.

Switching on AG Connect boards is implemented by the FMIC chip. Applications can address the MVIP switch using the MVIP-95 or MVIP-90 switch block model (see Section 5.2).

Switching operations for the AG Connect board can be controlled by the following:
Switch Commands

 Description

CT Access Switching service

 Service providing a set of functions for controlling MVIP switches. May be used for MVIP-90 and MVIP-95 device drivers.
For more information, see the CT Access Developer's Manual.

swish utility

 CT Access utility which controls MVIP switches. May be used for MVIP-90 and MVIP-95 device drivers.
For more information, see the CT Access Developer's Manual.

If CT Access 2.1 or greater is not installed, you must use MVIP-90 raw driver commands to set up switch connections to and from the board (as shown in the rawdrvr demonstration program). Refer to Section 7.2.3 for more information.

Note: We strongly recommend using the MVIP-95 switch model to develop new applications. The MVIP-95 model provides forward compatibility, and is designed to accommodate further telephony bus evolution. Although AG Connect boards are MVIP-90 boards, they can be accessed using the MVIP-95 model.

5.2 AG Connect MVIP Switch Models

This section describes the MVIP-90 and MVIP-95 switch models for the AG Connect.

5.2.1 AG Connect MVIP Switch Model (MVIP-90)

For AG Connect boards, the specific use of each stream is as follows:
MVIP-90 Streams/Timeslots

 Use

Streams 0..15 (each stream has timeslots 0..31)

 MVIP bus (8 streams with forward connections and 8 streams with reverse connections).

Streams 16 and 17 (each stream has timeslots 0..31)

 AG Connect line interfaces. Stream 16 carries voice information and stream 17 carries signaling information.

The line interfaces are accessed via the timeslots 0...23. Each line interface n is assigned timeslot number (n-1). For example, the voice information for the first line interface on the board is carried on Stream:Timeslot 16:0. The signaling information for the second line interface is carried on Stream:Timeslot 17:1.

Stream 18

 Reserved for line interface configuration. Applications should not access timeslots on stream 18.

Stream 19

 Local stream with 0 time slots. It is reserved for future use.

Streams 20..40, each with timeslots 0..31

 Available for conferences. A maximum of 16 conference seats are available in up to 5 conferences. For more information, see Section 5.6.

Figure 9 shows the complete MVIP-90 switch model:

Figure 9. MVIP-90 Switching Model for AG Connect Board





5.2.2	 AG Connect MVIP Switch Model (MVIP-95)





For AG Connect boards, the specific use of each stream is as follows: 





 MVIP-95 Streams/Timeslots



 Use




 Streams 0..15 (each stream has timeslots 0..31)



 MVIP bus.




 Local streams 0 and 1 (each stream has timeslots 0..31)



 AG Connect line interfaces. Local streams 0 and 1 carry voice information.


 The line interfaces are accessed via the timeslots 0...23. Each line interface n is assigned timeslot number (n-1). For example, the voice information for the first line interface on the board is carried on 0:0 and 1:0. 




 Local streams 2 and 3 (each stream has timeslots 0..31)



 AG Connect line interfaces. Timeslots on local streams 2 and 3 carry signaling information associated with the voice information in the same timeslots on streams 0 and 1.


 The line interfaces are accessed via the timeslots 0...23. Each line interface n is assigned timeslot number (n-1). For example, the signaling information for the second line interface is carried on 2:1 and 3:1.




 Local streams 4 and 5



 Reserved for line interface configuration. Applications should not access timeslots on these streams.




 Local streams 6 and 7



 Reserved for future use. 0 time slots.




 Streams 8..49, each with timeslots 0..31



 Available for conferences. A maximum of 16 conference seats are available in up to 5 conferences. For more information, see Section 5.6.
















Figure 10 shows the MVIP-95 switch model:






Figure 10.	 MVIP-95 Switch Model for AG Connect Boards






5.3	 Hybrids and Timeslots on the Local Bus





On the AG Connect boards, each line interface is hardwired to a specific timeslot on the local bus. Each line interface supports one port of telephone network connectivity. Figure 11 shows how line interfaces are mapped to timeslots.






Figure 11.	 Timeslots and Line Interfaces on the AG Connect Board




Each line interface is also permanently connected to pins on the DB-62 connector on the end bracket. See Appendix D to learn how line interfaces map to pins.






5.4	 FMIC Switching Restrictions





The MVIP-90 Switching Standard is designed to use full duplex streams. When making a full duplex connection using stream 0, the timeslot on DSo0 is used to receive input, and output is driven onto the same timeslot on DSi0. For example:


MakeConnection ( 0:3 to 16:6 )         /* connects DSo0:3 to local stream 16:6 */
MakeConnection ( 16:6 to 0:3 )         /* connects local stream 16:6 to DSi0:3 */




The FMIC chip was built for implementing MVIP-90 switching. It has a "direction" bit in its connection memory for each timeslot that selects either of the following modes:




The FMIC cannot simultaneously send output to both DSi and DSo on the same timeslot on the same-numbered stream, and also cannot simultaneously receive input from both DSi and DSo on the same timeslot. Note that this restriction exists for MVIP timeslots only: local timeslots have no direction associated with them.



Thus if the following MVIP-90 simplex connection is made:


MakeConnection ( 0:3 to 16:6 )         /* connects DSo0:3 to local stream 16:6 */




...then the FMIC establishes DSo0:3 as an input timeslot, and also establishes DSi0:3 as an output timeslot. Even though there are no switch connections made to DSi0:3, the switch block cannot receive input from DSi0:3 because the direction is currently set to "output" for that timeslot in the FMIC. Thus a connection such as the following would cause an error:


MakeConnection ( 8:3 to 18:6 )        /* connects DSi0:3 to local stream 18:6 */




...since this connection attempts to receive input from DSi0:3. 



Here is the same duplex connection as the one shown above, in MVIP-95 terms:


MakeConnection (mvip:0:3 to local:1:6) /*connects DSo0:3 to loc. str. 1:6 */
MakeConnection (local:0:6 to mvip:1:3) /*connects loc. str. 0:6 to DSi0:3 */




When a connection is made using stream 0 timeslot 3, the direction is set for timeslot 3 on stream 1. Stream 0 corresponds to DSo0, and stream 1 corresponds to DSi0. Thus a connection like the following would cause an error:


MakeConnection (mvip:1:3 to local:5:2) /* connects DSi0:3 to loc. str. 5:2*/




The "direction" bit for a timeslot may not be changed until all connections involving the timeslot have been broken. At that point, the next connection involving that timeslot resets its "direction" bit to a new direction.







5.4.1	 Practical Outcomes of the FMIC Limitation





In most applications, this switching restriction is completely invisible. However, you cannot connect the local resources of a card with an FMIC, such as an AG-T1 or AG Connect, over the MVIP bus. Those connections must be made locally on the FMIC. Local timeslots have no direction associated with them.



For example, with an AG Connect, you cannot connect line interface 0 to line interface 1 over the MVIP bus, as shown here (in MVIP-90 terms):


MakeConnection ( 16:0 to 0:0 duplex ) /* connects line int. 0 to DSo0:0 */
MakeConnection ( 8:0 to 16:1 duplex ) /* connects DSi0:0 to line int. 1 */




...since the first connection sets the direction bit for DSo0:0 to "output," and also sets the bit for DSi0:0 to "input". The second connection attempts to receive input from DSi0:0, which is now illegal. The correct way to connect line interface 0 to line interface 1 would be locally, as shown here:


MVIP90:  MakeConnection (16:0 to 16:1 duplex)

MVIP95:  MakeConnection (local:0:0 to local:1:1)
       MakeConnection (local:0:1 to local:1:0)




If you are migrating to AG Connect boards from ATI or ASI boards, the FMIC limitation means that your switching programming must change. This is because all local-to-local connections on ATI or ASI boards must be done over the MVIP bus. 



If a connection is unavailable because the direction bit for the timeslot is set oppositely, the MVIP switching driver returns error code MVIP_NO_PATH.






5.5	 MVIP Clocking





In an MVIP system, the bus clock for each board must be synchronized with the clocks on other boards. This means that all MVIP boards in the system must be driven by the same clock source. 



The AG Connect board can be configured as an MVIP clock master or slave. When the AG board is initialized, by default it is configured as a clock slave. It checks for a clock signal and does the following:




For more information about MVIP clock configuration, see the Switching Service Developers Reference Manual.






5.6	 Conferencing





S Connect-x With Ringing boards support telephone conferences, where two or more parties are connected together in such a way that any party can speak to and/or hear any other party. 



In your application, you can use standard CT Access Switching service commands to establish and disconnect conferences. In addition, you can control various conferencing parameters, such as gain or noise suppression. These parameters can be monitored for a given party, for a conference or for all conferences. You can also get status information at each of these levels.



Conferencing is founded on two resources: conferences and conference seats.




Managing AG Connect conferencing resources can be likened to managing a convention center (see Figure 12 below). The center has 5 conference rooms. Each conference room has a 32-seat maximum capacity. 



The conference rooms each have tables but not seats. The seats are kept in a pool and allocated to conferences as needed. The building has a pool of 16 seats. As parties arrive, they carry seats to the appropriate conferences. As parties depart, their seats are returned to the pool for later use in another conference.






Figure 12.	 Conferences and Conference Seats




Each conference is a local stream on an MVIP switch, with 32 timeslots. To establish conferences and connect or disconnect parties, you simply make connections between these local streams and standard switch streams.



Each conference seat is a timeslot in a conference stream. Any conference timeslot connected to another timeslot is considered an active seat. The AG Connect conference chip can handle up to 16 total active seats. Since conference streams have 32 timeslots each, a single conference may host all of these active seats.


Note:  To insure acceptable speech quality, no more than 8 seats should be connected to a single conference.


Each connection may be simplex (one way), duplex (two way), or pattern mode (in which a certain pattern of data is repeated in the timeslot in each frame). Typically, connections are duplex.



For more information on establishing conferences and using conference commands, see the Conferencing Developer's Reference Manual.








 
    (Page 1 of 1 in this chapter)




 




tech_support@nmss.com



Copyright © 1999, Natural MicroSystems, Inc.   All rights
reserved.