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Spirent TestCenter : What is the use of "Subset Decode Range" in capture menu?

Answer

Customer question was that after changing the start/end frame index values before start of capture, why is the buffer showing all the frames that were received and captured?

We explained that the subset decode range is not acting like a capture filter.
So it doesn't’t filter out packets before adding them to capture buffer.
Instead, it allows you to download a subset of captured frames from the buffer.
Once you start capture, buffer will store all the packets that are received, to the capture buffer memory limit.
Later the “frame index” lets you specify the range of frames that you want to take out from the whole buffer.

Example:
·         2 ports back to back, and port 1 sending a burst of 1000 frames and other port 2 capturing.
·         The port 2 capture buffer will have 1000 packets and it will display it.
·         Give starting frame index of “0” and ending frame index of “250” and click “view”, will download the first 250 frames from the buffer
·         Give starting frame index of “100” and ending frame index of “150” and click “view”, will download the 50 frames starting with frame number 100 from the buffer
·         Give starting frame index of “0” and ending frame index of “0” and click “view”, will download the whole 1000 frames from the buffer

 


Product : Spirent TestCenter