Agilent Technologies 622Vu Advisor, User Manual

Page: 143 / 244

For purposes of illustration, as-
sume we want to specify idle
cells as those having zeros in
the last five bits of the VCI, and
a 1 in the first bit of the PTI.
Our match settings look like
this. (
indicates bits that are
not examined):
Match
VCI PTI
GFC
VPI
CLP
Bit:
Byte 1 Byte 2 Byte 3 Byte 4
8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
X X X X X X X X X
Mask
X X X X 0 0 0 1 1 1 1 1
1
X X X X X X X X X X X X 0 0
1 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Use either hexadecimal or decimal values to indicate the settings you want,
to correspond to the current Options menu setting for Show Header Values
in Decimal Format.
8.4 Defining Filter Buffers
As described previously, the filtering process uses 1–4 predefined buffers to store
cell captures while you’re monitoring incoming traffic (described in Chapter 6).
Each buffer is allocated a certain percentage of the total memory available (32
MB) on the analysis device for captures.
During capture processing, incoming cells are stored in the first buffer where a
match is found between the cell and specific filtering criteria (established via the
buffer’s filter entries). A filterset option controls the action taken when a
buffer’s memory is exhausted (either wrap traffic back to the beginning or stop
capturing, as described on page 140).
This section describes how to add a new filter buffer (either from scratch or by
cloning a buffer that’s defined already), to remove a buffer, to shift a buffer up or
down within the filter definition, and to modify a buffer’s definition. The
definition specifies the amount of memory available for each buffer.
Two types of buffers, CaptureAll and BadHec, are reserved for use by the system
(see page 131). You can modify the definitions of these buffers, but you can’t
delete them.
8: Filtering Captures
8.4 Defining Filter Buffers
143