Sniffer® Portable Professional User's Guide - NetScout

Capturing Packets
When Buffer is Full. Select to automatically stop the capture
(Stop capture) when the buffer is full or overwrite older data
in the buffer (Wrap buffer). You can select these options only
if the Save to File option is disabled.
Packet Size. You can save the entire packet in the capture
buffer, or truncate each packet by setting the Packet Size
option when defining a capture filter. Move the slider to select
the size of the packet to be captured and saved in the buffer.
A data packet size greater than the specified size will be
truncated. You can select Whole packet, 64, 128, 256, 512,
1024, 4096, 8192, 16384, or 18432 bytes.
By truncating large packets, you can save more packets in
the capture buffer, thus extending the time covered by the
capture and reducing the size of the capture data file, saving
disk space (assuming you save the capture buffer to disk).
On a very busy network, truncating frames may also help
avoid losing frames, since longer frames take longer to store.
Save to File. You can set the Filename prefix and the
Number of files to be spooled. The maximum number of files
allowed is 99,999.
Each file is the same size as the defined capture buffer. For
example, if you select the 4 MB buffer size, each file created
will be 4 MB in size. (The last file size may be smaller than 4
MB.) Setting the buffer size to between 8 and 12 MB will
improve capture performance.
You may select the Unique names option to guarantee that
the file names created by packet capture are unique when
being stored in the same directory. This is a useful option
when you use packet capture spooling in conjunction with the
capture trigger repeat mode. Several packet capture
sequences can be saved without overwriting earlier
sequences.
By selecting the Wrap file names option, the capture will
continue to spool to disk files, overwriting the first file if the
last file is full. Otherwise, the capture will stop once it
reaches the end of the last file.
3 If you would like to start capture based on the specified filter
criteria, click Start Capture directly from the Define Filter dialog
box. This action saves the filter criteria and starts a capture based
on the active filter in the dialog box.
4 If you would like to save the filter criteria, click OK.
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