Chapter 9: Ethernet Cards
Gigabit Frame Rate Calculation
SmartBits System Reference 131
Capacity Utilization by Streams
In the LAN-620x SmartModules, the frames are generated by individual streams. Each
stream has its own frame generation definition and each stream utilizes part of the total
payload capacity available. So, capacity utilization by any stream is:
Stream Capacity Utilization (Bps) = (stream frame rate) * (frame size + 12 (inter-
frame gap) + 8 (minimum preamble) + 4 (CRC) )
and
Aggregate Stream Capacity Utilization = sum of individual Stream Capacity
Utilization
Even though streams are independent of each other, the Stream Capacity Utilization of one
stream may affect the Stream Capacity Utilization of another stream, especially if the
frames rates are different.
The frame rates for the LAN-320x modules fall into four categories, each with an
independent clock source:
• Frame Rate
• Clock Rate
• InterFrameTime
• Calculated Rate
Refer to the SmartWindow User Guide, located at http://www.netcomsystems.com/
support/documentation.asp for detailed information regarding applicable tests and
features.
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