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debug flow basic

Created by dave. Last edited by dave, 7 years and 71 days ago. Viewed 1,987 times. #1
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1set console dbufSet debugs to be redirected to the debug buffer. It is too CPU intensive to send to the console. The command 'get console' should report 'debug:buffer'.
2undebug allTurn off any debugs, just to be safe.
3set db size 4096(Optional) Increase the debug buffer. The debug buffer is circular. If you need to capture a lot of data, set the debug buffer to the maximum size of 4096 (4 MB). Use the command 'get db info' to see the current size of the debug buffer in KB.
Note: You could alternatively send debug output to a USB drive, which would allow you to have a > 4 MB dbuf buffer. See KB12277 for further details.
4get ffilterDisplay any configured flow filters (ffilter). No filters are expected to be set at this time. If you see flow filters listed that are not applicable to your debug test, you can delete them with the command 'unset ffilter'.
5set ffilter src-ip x.x.x.x dst-ip y.y.y.y
set ffilter src-ip y.y.y.y dst-ip x.x.x.x
Set flow filters (ffilter) to observe specific packets flowing in each direction, and where any possible problems may be. Basically, you want to define the end points of communication to limit what is captured in the debug buffer.
For more information on flow filters, refer to KB6709 - Understanding debug ffilters.
6clear dbClear the debug buffer.
7debug flow basicStart the debug, specifically the 'flow' debug.
8 Initiate the traffic that you are interested in capturing.
9undebug allTurn debugs off and stop writing to the circular debug buffer. Run this command as soon as Step 8 is finished to avoid overwriting what was captured in the debug buffer.
Note: You can also press the ESC key to stop debug and snoop, with a single keystroke.
10get db streamDisplay what was captured in the debug buffer. You can also enter 'get db stream > tftp <ipaddr> <filename>' to redirect the debug buffer to a file.
11unset ffilterRemove the flow filters. Enter this command twice (once for each filter step in step 5). Use the command 'get ffilter' to see if the filters are removed.
12unset db sizeSet the debug buffer size back to the default buffer size. Use the command 'get db info' to see the current size of the debug buffer in KB.
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