Agilent Technologies 622Vu Advisor, Руководство пользователя

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Again, an exception occurs if the filterset is set up to capture everything, in
which case idle cells go into the standard CaptureAll buffer.
Click to specify a filterset mask; filtering
specifications that are combined with each
filter entry to form composite criteria.
Click to wrap the memory
allocated to each individual buffer
when it’s full, thereby overwriting
previously captured cells.
Click to capture bad HEC cells
(always selected for filtersets
that capture everything).
Click to capture
idle cells.
Mark the Advanced Filtering Mode box if you want to extend the basic filtering
capabilities of the system. (This feature isn’t applicable for everything-type
filtersets; i.e., CaptureAll buffers.) By default (without using advanced
filtering), 622Vu Advisor lets you select cells based on bit settings in the first
three header fields (GFC, VPI, and VCI). Collectively, these fields comprise the
cell’s address (path). With advanced filtering in effect, you can also select based
on the remaining header fields (PTI, CLP, and HEC) as well as the first byte of
the cell’s payload.
If you mark this box, refer to Section 8.6 Advanced Filtering Mode (page 149)
for the specifics of using a filtering mask.
Note: The advanced filtering feature is very powerful, and can lead to unexpected results unless
you’re careful. For most users the standard filter-entry criteria provide all the power
necessary.
The Wrap Buffers When Full option applies for all buffers defined for the
filterset, and indicates whether to:
•
Reuse each buffer continually until the capture is stopped, essentially
creating a circular buffer (box is marked).
•
Fill up each buffer once, then stop collecting the corresponding cells (box not
marked). Cells that would otherwise be stored in the buffer are discarded;
they don’t fall through to any other buffers that match their content. When
all buffers are full, the capture stops automatically.
If you wrap buffers, 622Vu Advisor writes over cells that have already been
stored on the analysis device after the buffer is full. This is useful, for example,
if you’re tracking a particular problem(s) and aren’t interested in saving the
traffic until the problem occurs. In this situation, you can stop the capture
immediately after the problem presents itself on the ATM device being tested,
and the traffic passing through the analysis device at the time of the problem will
8: Filtering Captures
8.3 Defining FilterSets
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