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Cisco Switch Monitor port

Trying on two model's of cisco switches to get a monitoring port working.  I've found the cisco page to do this and according to it all that needs to be done is:
config mode choose the port you want to be the source port interface Fa0/1 or whatever

then choose the ports you want to monitor by:
port monitor fa0/2...

However i'm on a 3560 and the port monitor command isn't even an option at this point.  Is there something needed to turn this on first?
Thanks,
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stamperb
Asked:
stamperb
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1 Solution
 
ctrostCommented:
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stamperbAuthor Commented:
OK i've got it going but when i try to add a second destination port i get:
% This platform allows a maximum of 1 monitor destination(s)

Now this is on a 4507R... I'd presume it can do more than this.
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stamperbAuthor Commented:
Maybe the whole story would help.  I have a snort box that i want to monitor my LAN with.  My lan consists of a core 4507R and about 12 3560's.  Each of the 3560's is connected back to the 4507R via fiber.  So presumably i'd place the snort ids box on a port monitoring all the other switches and ports.  Just need to figure out how to do this.
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ctrostCommented:
"A destination port can participate in only one SPAN session at a time. A destination port in one SPAN session cannot be a destination port for a second SPAN session."

4507R(config)#monitor session 1 source interface fastethernet 4/2
!--- This configures interface Fast Ethernet 4/2 as source port.

4507R(config)#monitor session 1 destination interface fastethernet 4/3
!--- The configures interface Fast Ethernet 0/3 as destination port.

Then try doing "monitor session 2 source" and "monitor session 2 destination".  You need different SPAN sessions for each port you want to monitor..................................... I think.


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stamperbAuthor Commented:
So the answer is simply that I can not monitor more than 1 port at a time?  I can't hardly believe that is the case.  If this was the case how would IDS work at all in a switched environment.  I know on the HP switches you tell it what port to source and all the destination ports.  
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ctrostCommented:
?? Yes you can, just create multiple sessions like above...  then do:
show monitor session 1...or
show monitor session 2

or just show monitor session

i really believe all the information you need (informational as well as configurational) is on the link I posted above......to be honest I don't know anything more about it than you do, I'm just relaying information from that webpage as I interpret it

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stamperbAuthor Commented:
OK well i did that for 1 session.  So basically monitoring 1 port that came from 1 of the 3560's.  I no more than turned it on before i hear people next to me saying they've lost connectivity to the exchange server and other shares.  I decided maybe this was a fluke and changed it to another one on a different floor.  Again I heard that people were having issues?  So i presume its causing some problems?  Would this really be the case?  I can't see that it would be dropping things like this for just 1 port worth of traffic?
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