Unisys NX5820 manual Assigning Channel Loads, Ciom CS-Bus Channel Loading, Maximum Connectivity

Configuring Channels

Assigning Channel Loads

Table 5–3 provides CS-bus loading guidelines for the various channel configurations. CS-bus loading is dependent on bus demand factor (BDF), which provides a gauge of CS- bus availability when the channel requires service. When there are many channels on the CS-bus vying for service simultaneously, there is a low probability of any one of the channels being granted instantaneous access to the bus. Such a configuration would offer greater connectivity, but the BDF would be low. Conversely, if the channel requires immediate access to the bus, the BDF would be high. Such a configuration would offer greater performance.

In Table 5–3, note that BDF increases as the bus demand increases such that at maximum performance, connectivity is of secondary importance; conversely, at maximum connectivity, performance is of secondary importance. The balanced performance/connectivity column reflects loading where performance and connectivity receive approximately equal consideration.

Note: To achieve results representative of the performance and connectivity profiles in the tables, it is recommended that bus loading be limited to sixteen loads per bus for CIOM CS-Busses.

Table 5–3. CIOM CS-Bus Channel Loading

		Bus Demand Factor1
Channel Type	Maximum	Balanced	Maximum Connectivity
	Performance	Performance/Connectivity
802.3 (two ports)	3 loads	1 load	1 load
ATM (full duplex) 2	8 loads	4 loads	2 loads
FDDI/CDDI	5 loads	1 load	1 load
Fibre	8 loads	4 loads	4 loads
MAINTLAN	1 load	1 load	1 load
MLI	6 loads	2 loads	1 load
PCI thru	10 loads	4 loads	2 loads
SCSI-2N	8 loads	2 loads	1 load
SCSI-2W	10 loads	3 loads	2 loads
SCSI-ULTRA	12 loads	3 loads	2 loads
Notes:

1.BDF = Equivalent loads per channel.

2.Refer to ATM Channel Adapter Style CA6552–OC3 Configuration Guide in the About This Guide section for loading applicable to specific configurations.

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