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Tim LewisFlag for United States of America

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cisco 3560G Span port

Hello,

We are inserting a IDS appliance into our system and need to setup a span port for it to use.  I am not really clear on how to do this.  The Cisco 3560 switch connects to our asa firewall which is in routed mode via a trunk port on port 12 of the switch.  I assume this is the best port to monitor?  I have an open port 15 that I was going to connect to the IDS system.  Would the correct command be
monitor session 1 source interface fastethernet 0/12  
&
monitor session 1 destination interface fastethernet 0/15

I have never done this before and am looking for any help or advice to make sure this looks ok and will not cause any issues on the switch/network doing it like this.  Any help is appreciated.

Thank you
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Cyclops3590
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Thank you. Does doing this affect the monitored port in anyway?
not that i've ever seen.  there's clearly going to be resources used by the switch to do the operation but none that should affect the actual data traffic.
I found that the command to monitor should be monitor session 1 destination interface fastethernet 0/15 encapsulation replicate.    otherwise good to go.  Thanks for the help