2.3.  Blocking Data Streams

• 2.3.1.  Blocking Considerations
• 2.3.2.  Blocking Example

If the total time slot requirement of your multi-node system exceeds the 1024 time slot limitation of the SCxbus, SCbus data streams (bundles of time slots) could be blocked within a node from being transmitted onto the SCxbus. In this blocking scenario, up to 4,096 time slots can be made available in the multi-node system.

The resources (e.g., voice, analog or digital) whose time slots are blocked from transmitting onto the SCxbus can be shared locally within their local node. The SCxbus data streams that correspond to these locally blocked time slots are not used. Therefore, no data is transmitted or received on these data streams by the SCX160 SCxbus Adapter.

NOTE:

The data stream blocking scheme increases the complexity of resource management and should only be used for multi-node systems that exceed the 1024 time slot limitation. Blocking only increases the effective number of time slots in the multi-node system and does not change the 1024 time slot limitation of the SCbus in each node.

In Figure 2.  Blocking Example, voice resource time slots at each of the four nodes are blocked from transmitting onto the SCxbus. Since Node 3 requires the largest number of data streams (three) to block the 144 time slots used by the local voice resources, three data streams must be blocked in all nodes. In this example, all voice resources are limited to resource sharing in their local nodes while all other resources can communicate and be shared among all nodes.

Figure 2.  Blocking Example

2.3.1.  Blocking Considerations

To configure blocking requires knowing:

• The configuration of each node (the boards installed and resources available on each board). Refer to the Dialogic Node Configuration Chart in the SCX160 SCxbus Adapter Package Release Notes.
• The resources to be blocked in each node from the SCxbus (e.g., voice, analog or digital).
• The number of data streams to be blocked at each node.

Refer to Appendix B - Dialogic SCX160 Configuration Program for procedures on how to set up blocking. The following considerations apply to blocking:

• Only the time slots for one resource (e.g., voice, analog or digital) can be blocked per node.
• When blocking time slots for a resource in a node, the number of data streams blocked must include all the time slots being used for that resource (e.g., if five D/240SC - T1 boards reside in Node 1 and voice resources are blocked then two data streams (128 time slots) must be blocked from the SCxbus because the voice resources on these boards require 120 time slots).
• Time slots for a different resource can be blocked in each node (e.g., Node 1 can block time slots for the voice resource and Node 2 can block time slots for the digital resource).
• The number of data streams to be blocked from the SCxbus must be the same for each node in the system. This number must be equal to or greater than the largest number of data streams to be blocked in any node.

2.3.2.  Blocking Example

The configuration presented in Table 3.  Multi-node Configuration Without Blocking Example illustrates a multi-node system that exceeds the SCxbus 1024 time slot limitation. The multi-node system comprises four nodes that contain one or more voice and network boards in addition to an SCX160 Adapter board. As Table 3.  Multi-node Configuration Without Blocking Example illustrates, without blocking, the multi-node system exceeds the 16 data stream (1024 time slots) limitation of the SCxbus.

Table 3.  Multi-node Configuration Without Blocking Example

Node	Node Configuration	DTI Time Slots	Voice Time Slots	Total Time Slots / Data Streams Used	# of SCxbus Data Streams
1	5xD/240SC-T1 + 1xDTI/240SC + 1xSCX/160	5x24+ 1x24=144	5x24=120 (2 data streams)	144+120=264 (5 data streams)	5
2	5xDTI/241SC + 1xSCX/160	5x24=120	5x24=120 (2 data streams)	120+120=240 (4 data streams)	4
3	6xD/240SC-T1 + 1xSCX/160	6x24=144	6x24=144 (3 data streams)	144+144=288 (5 data streams)	5
4	5xDTI/241SC + 1xD/160SC + 1xSCX/160	5x24=120	5x24+1x16=136 (3 data streams)	120+136=256 (4 data streams)	4
TOTAL =					18

However, all the resources of this example can be used by the multi-node system by blocking the voice resources from the SCxbus in each node. Since the largest number of data streams required for voice resources is three data streams in Nodes 3 and 4 (refer to Table 4.  Determining Number of Data Streams to Block), three data streams must be blocked in each node in the system.

Table 4.  Determining Number of Data Streams to Block

Node	# of Voice Time Slots Used	# of Data Streams Required
1	120	2
2	120	2
3	144	3
4	136	3

In Table 5.  Multi-node Configuration With Blocking Example, the voice resources are blocked from the SCxbus in each node. With blocking, all desired resources can be used while only using ten SCxbus data streams. Ten data streams are actually transmitting on the SCxbus for a total of 640 time slots and three data streams (equivalent to 192 time slots) are blocked in each node. In this system, 1,048 time slots are actually being used by the currently installed resources. However, the system has the potential to use up to 832 (13 data streams x 64) SCxbus time slots plus 768 local SCbus time slots (192 x 4 nodes) for a total of 1,590 time slots.

Table 5.  Multi-node Configuration With Blocking Example

Node	Node Configuration	DTI Time Slots	Voice Time Slots	Total Time Slots / Data Streams Used	# of SCxbus Data Streams
1	5xD/240SC-T1 + 1xDTI/240SC + 1xSCX/160	5x24+ 1x24=144	5x24=120 (2 data streams)	144+120=264 (5 data streams)	3
2	5xDTI/241SC + 1xSCX/160	5x24=120	5x24=120 (2 data streams)	120+120=240 (4 data streams)	2
3	6xD/240SC-T1 + 1xSCX/160	6x24=144	6x24=144 (3 data streams)	144+144=288 (5 data streams)	3
4	5xDTI/241SC + 1xD/160SC + 1xSCX/160	5x24=120	5x24+1x16=136 (3 data streams)	120+136=256 (4 data streams)	2
				TOTAL =	10

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