Chapter 2: System Architecture
Traffic Generation and Performance Analysis
24 SmartBits System Reference
Multiple frame
blueprints,
different
protocols, and
varied frame
sizes per stream.
Figure 2-8. Three Streams (frame blueprints) on a single SmartMetrics port
There are three different traffic loading methods used with SmartBits cards:
• Round-Robin Traffic Loading. The default transmit order for SmartCards that
support multiple stream definitions is a round-robin order based on the stream index.
One frame is sent from each stream definition starting at index 1 until all streams have
been transmitted. Then the process is repeated.
This means that the percentage of a given type of traffic is dependent on the number of
stream definitions that have been defined with the given characteristics. If thirty
streams are defined with a high QOS, and seventy streams are defined with a low
QOS, thirty percent of the traffic will have the high QOS.
• Sequencer Traffic Loading. This method sets the rate and transmit mode on a per-
port basis.
• Scheduler Traffic Loading. Available with the POS-6500 and LAN-6201 card
families, the Scheduler method allows you to specify rate (frames per second) on a
per-stream basis, unlike other cards where the traffic rate is set with a global, per-port
interframe gap. These cards can calculate the gap for you. If you oversubscribe the
card, (i.e., specify a combination of number of streams and frame rates that causes
more traffic than the medium is capable), an error is generated.
This feature provides the ability to set multiple rates on a single port, and allows you
to calculate percentages of different traffic types by setting frames-per-second on a
per stream basis.
For basic rate calculation, refer to the SmartLib User Guide.Foraquick,easyGUI
representation, you can also use the SmartWindow Rate/Load calculator, available in
the Transmit Setup for the POS-6500 and LAN-6201 cards.
MAC Dest MAC Src
MAC Dest MAC Src
MAC Dest MAC Src
IPX
IP
TCP
Prot Header
Prot Header
Prot Header
Payload
Payload
Payload
Signature
Signature
Signature
CRC
CRC
CRC
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