JDS Uniphase SmartClass, User Manual

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Chapter 7 Interpreting Test Results
ATM results
SmartClass ADSL/Copper Tester User’s Guide 49
ATM results
Table 10 describes the ATM test results.
Graphs
The graphs provide a graphical representation of the bits per tone (BPT),
signal to noise ratio (SNR), and noise per tone. Only two graphs are available
at one time: BPT and either SNR or Noise (depending on your selection for
GRAPH on the WAN SETUP menu).
SNR indicates line quality. The BPT graph indicates the total bit rate and is a
useful tool for finding disturbers.
Figure 9 illustrates a BPT graph.
DROPPED CELL
CNT Total number of dropped cells. The ATM network will dis-
card or “drop” erred cells which must then be retransmit-
ted (this is done automatically). The SmartClass counts
the number of ATM cells and how many were dropped,
giving an indication of service quality.
Table 9 ATM general results (Continued)
Result Definition
Table 10 ATM results
Result Definition
TX/RX PDU The PDU upon which cells are being transmitted or
received.
TX/RX AAL5 BYTES Number of ATM Adaptation Layer 5 bytes transmitted or
received. Since ATM can carry different types of user
data (such as web pages or voice), ATM layers are
defined to carry the different types of data effectively. For
normal, non-time sensitive data, such as e-mail and user
files, AAL5 is used. Multiple ATM cells are grouped
together in frames to carry large amounts of user data
over the network.
TOTAL ERROR CNT Total number of ATM errors, including bad HEC and
dropped cells.
Figure 9 Bits per tone graph (example)