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Configuring Channels
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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 Factor
1
Channel Type Maximum
Performance
Balanced
Performance/Connectivity
Maximum 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.