Atec Agilent-J2300E - Manual (Page 15)

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Shaping of test cell traffic and background traffic
There are two sides to any contract and ATM traffic contracts are no exception.
If the user traffic keeps to its contract obligations then the network should
deliver the quality of service it guarantees in the traffic contract. This is usually
specified in terms of cell loss and added cell delay variation, etc.
The Agilent Advisor is able to measure ATM layer QoS by generating test traffic
shaped to meet the traffic contract in terms of PCR, CDVT, SCR and MBS; it
also allows users to choose the standardized “Generic List” values for the
parameters. The test traffic comprises test cells which conform to ITU-T
Recommendation O.191 which specifies the test cell and the methodology for
measuring ATM layer QoS parameters specified in ITU-T Recommendations
I.356 and I.357, and the ATM Forum’s Traffic Management Specification version
4.1. Measurements made by the Agilent Advisor are as follows:
Cell Loss Ratio
Cell Misinsertion Rate
Cell Error Ratio
Cell Delay Variation
Mean Cell Transfer Delay
Minimum Cell Transfer Delay
Maximum Cell Transfer Delay
Severely Errored Cell Block Ratio
Availability Ratio
Transmitted Cells
Non-Conforming Cells
Tagged Cells
Test traffic can be sent and received by the same Advisor for local testing or it
can be sent by one Advisor and received on the other side of the network by
another. Each Agilent Advisor on either end of a connection, can source test
traffic in the opposite direction on the same bi-directional virtual connection
and, at the same time, analyze traffic from the other; each Advisor is configured
to source traffic conforming to the traffic contract for that direction of the
virtual connection; such connections are often asymmetrical. As conforming
test traffic is entering the network, any cell loss or cell delay variation detected
on the far side of the network must be caused by the network itself; this can be
compared with the SLA requirement to check that the network is complying
with its side of the agreement. The Advisor is also capable of generating same
link background traffic (on other virtual connections).
Figure 3: Traffic Configuration.
ATM Testing (continued)