3750 port monitor ? doesn't exist ?

Question

Ok I have a 3750, 24 port gigabit switch.

I want to monitor all traffic going to port 2 with port 1 .. on my other cisco's i can "port monitor" on the interface 1, but the 3750 doesn't have this command ?

It does have a "monitor" command at the "config t" level .. however if i supply port 2 as the source and port 1 as the destination, port 1 stops working ? in show interface 1 it says port up but administratively down (monitoring) ???

I dont want either port to stop working .. what is the equiv of port monitor on these 3750's ?

Anthony · Accepted Answer

The monitor command is what you want to use. The interface will show FastEthernet1/0/xx is up, line protocol is down (monitoring). This is normal behavior of the interface. The protocol is down (monitoring) specifying that this is a dest port.

Now if your sniffer needs to send traffic, the default for the 3750 is to not allow "ingress" traffic from the sniffer equipment. You will need to allow this in the configuration with the destination option of the monitor command.

monitor session session_number destination {interface interface-id [, |

-] [encapsulation replicate] [ingress {dot1q vlan vlan-id | isl | untagged vlan vlan-id | vlan vlan-id}]}

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3750 port monitor ? doesn't exist ?

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