Traffic Control And Multiplexing Method - Wavetek ANT-20 Operating Manual

ANT-20/ANT-20E
1.4

Traffic Control and Multiplexing Method

As well as being able to set the source parameters "off-line", i.e. before starting the
measurement, the "ATM Test Control" VI also allows you to change all the relevant source
parameters "on-line", i.e. during a measurement. The parameters are defined off-line using the
"Test Setup" dialog (b) (see Fig. TB-4). In contrast, the "Test Online Control" dialog (c) is used
to alter parameters on-line. Please note that each change in a source parameter results in a
complete re-calculation of the entire multiplex.
Users should be aware that ATM multiplex formation makes it unavoidable that a changed
setting in one channel (e.g Channel A, see index card (a)) may also affect the other channels
(i.e. Channels B, C and D). This is particularly the case where the physical link is loaded to a
high percentage.
The channel priorities for the multiplex procedure are fixed by two rules, whereby rule 1 has
precedence over rule 2.
Rule 1
Channels with a bit rate above 2.5 Mbit/s have priority over channels with a bit rate below 2.5
Mbit/s. This rule takes account of the fact that lower bit rate channels usually allow a higher
CDVT than that of higher bit rate channels.
Rule 2
The priority of the channels decreases from left to right, i.e. channel A has the highest priority,
channel B the next highest, and so on.
Technical Background
Broadband Analyzer/Generator
TB-5