juniper debug

– Allows for the viewing of the debug output as a whole, instead of line by line on the console screen
• Since console output is not viewable from a telnet or secure shell connection, the debug buffer can also be used for viewing snoop output from an telnet or secure shell connection
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Snoop Filter Details
• To view the configured snoop filter options and to see what options are available for setting:
– snoop info Snoop: Off, Interface: All, direction: incoming EtherType 0000, SrcIp 0.0.0.0, DstIp 0.0.0.0, Proto 0 SrcPort 0, DstPort 0 Ip(either src or dst) 0.0.0.0, Port(either src or dst) 0
– get dbuf info
• To show the total, allocated, and left (available) memory
– get mem
• To allocate system memory for the debug buffer
– set dbuf size <size>
• [ESC] only disables snoop or debug on the management processor • [ESC] does not disable snoop or debug on the session processors
NS Implementation and Configuration Rev00a
Debug Buffer “dbuf”
Understanding & Using The Debug Buffer
B R O A D B A N D
I N T E R N E T
S E C U R I T Y
S O L U T I O N S
Snoop & Debug Output
• Sending snoop & debug output to the debug buffer (recommended)
• The method of debug output
– sending debug output to a console the most CPU intensive – sending debug output to a debug buffer is much less CPU intensive
• snoop off
– To disable debug on all processor cards
• undebug all • debug <debug-option> 0 *(Where Applicable)
– Do not use [esc] to disable debug or snoop on the NS1000!!!
NS Implementation and Configuration Rev00a
NetScreen Technologies
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Snoop Status
• To view whether or not snoop is running:
– snoop info
Snoop: On, Interface: All, direction: incoming EtherType 0000, SrcIp 0.0.0.0, DstIp 0.0.0.0, Proto 0 SrcPort 0, DstPort 0 Ip(either src or dst) 0.0.0.0, Port(either src or dst) 0
– CLI settings
• set console dbuf • get console
– shows the debug is set to buffer
NS Implementation and Configuration Rev00a
NetScreen Technologies
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Snoop & Debug Output
NS Implementation and Configuration Rev00a
NetScreen Technologies
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Snoop Filter Details
• To set up the snoop options that allow filtering of frames that sent to the debug buffer or the console
– shows that snoop & debug output will be sent to console
NS Implementation and Configuration Rev00a
NetScreen Technologies
3
Debug Buffer (DBUF)
• To show the dbuf size in bytes
NS Implementation and Configuration Rev00a
NetScreen Technologies
4
Debug Buffer (DBUF)
• To view the contents of the debug buffer (dbuf)
– get dbuf stream
– It is recommended that snoop output be directed to the debug buffer instead of the console
NS Implementation and Configuration Rev00a
NetScreen Technologies
– snoop ? <return> direction ethernet info interface ip off snoop direction snoop specified ethernet show snoop information snoop which interface snoop ip packet turn off snoop
• The amount of traffic being sent through the NetScreen
– increases in traffic flow decrease the performance, for more data must be sent to the console or debug buffer
NS Implementation and Configuration Rev00a
NetScreen Technologies
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Snoop
• The snoop command gives a user the ability to view packet information from layer-2 up to layer-4 as it comes into and out of the NetScreen • Snoop output behaves the same way as debug output and the same principles apply as to how to handle snoop output
• If traffic flow is high, you may lose access to the console screen to perform any CLI commands including the disabling of debug
– CLI settings
• unset console dbuf • get console
– clear dbuf
NS Implementation and Configuration Rev00a
NetScreen Technologies
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NS1000 Warning
• NS1000 – Disabling snoop and debug
– To disable snoop on processor cards
• Snoop is a powerful troubleshooting tool, but it must be used with caution
– Causes a slow down in performance while debug is running – The performance drop depends on a few factors:
NetScreen Technologies
6
ScreenOS Snoop
Understanding & Using ScreenOS Snoop
B R O A D B A N D
I N T E R N E T
S E C U R I T Y
S O L U T I O N S
Snoop Warning!!!
• dbuf size should not be modified without checking to make sure there is an ample amount of memory available on the NetScreen to allocate for added debug buffer space • If the dbuf is capturing enough of the snoop or debug output for troubleshooting a problem, then the dbuf size does not need to be modified • If the debug output being stored is larger than the size of the dbuf • The snoop and debug output is stored first in first out (FIFO) • Newer entries are stored and older ones are overwritten