Spirent SmartBits System, Reference Manual

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Chapter 9: Ethernet Cards
Standard Ethernet Features
SmartBits System Reference 125
Latency Resolution
The range of accuracy of latency measurements (ns or ms).
Max # Flows per Stream
The number of SmartFlows possible per stream; for further definition, refer to “Traffic
Generation and Performance Analysis” on page 19 .
Max # Streams per Port
Maximum number of primary frame blueprints per port. For further definition, refer to
“Traffic Generation and Performance Analysis” on page 19 .
MPLS Labeling Insertion
Supports generation and analysis of Ethernet frames that contain MPLS label stacks in
accordance with the current IETF MPLS working group draft. As with VLAN frame
tagging, transmission of frames containing MPLS label stacks is a matter of appropriate
transmitter configuration.
The MPLS unicast (0x8847) or multicast (0x8848) Ethernet type field is inserted after the
source MAC address and then followed by the MPLS label stack. If a combination of
VLAN tagging and MPLS labeling is used, the MPLS label stack occurs after the VLAN
tag. No special action is taken on the receiver side when an MPLS frame is received.
However, the Ethernet interface is still responsible for locating the start of the IP header,
regardless of the existence and depth of the MPLS label stack.
Multimodal Frame Length (MMFL)
You can set the frame length of each TeraMetrics flow in one of three ways:
•
A fixed, user-specified frame length per flow.
•
A “uniform random” range of frame lengths via a user-specified minimum and
maximum length per port.
•
Multi-modal frame length (MMFL).
The MMFL feature will generate a random set of frame lengths whose distribution can be
completely controlled by the application software to represent whatever mix of traffic is
desired. The random frame lengths generated will apply globally to all streams generated
by the transmitting port.
The probability density function distribution may have up to 10 peaks. Each peak has a
gaussian distribution, with independently controllable width (standard deviation), mean
value (the length where the maximum probability occurs) and height relative to other
peaks.