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Port Monitoring

Created by dave. Last edited by dave, 9 years and 108 days ago. Viewed 5,063 times. #4
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Problem

I have a PowerConnect 3448. I am set up for port monitoring as so:

# show ports monitor

Source Port Destination Port Type Status VLAN Tagging ----------- ---------------- ------- ---------- ------------ g1 g4 RX,TX active No

g1 is a fiber connection coming in from my ISP uplink. g4 is a copper connection going to a network interface on my monitoring station.

The problem is that I only see half the traffic: I see the traffic going to the ISP on my mirror (ie outbound, ie TX), but I don't see the traffic coming back (ie inbound, ie RX).

I have tried the port in TX mode (still shows TX packets), and RX mode (shows nothing).

I know the internet is passing packets, because my customers would notice if it wasn't.

I'm pretty sure it isn't my monitoring station because the computer was previously hooked up to a 3Com SuperStack 4900 switch set up to "Roving Port Analysys" the fiber to a copper connection, and worked properly then. Nothing changed on the system side. We simply unplugged the 3Com (and threw it away, yay) and plugged in the PowerConnect.

My switch version is as so:

# show version
SW version 2.0.0.21 ( date 15-Jan-2007 time 15:48:02 )
Boot version 1.0.1.01 ( date 15-Jun-2006 time 11:42:56 )
HW version 00.00.01

(>>Link to Dell Site)

The Theory

console(config)# interface ethernet 1/e1
console(config-if)# port monitor 1/e2
console (config-if)# end
console# show ports monitor
Source Port Destination Port Type         Status  VLAN Tagging
----------- ---------------- ------------ ------- ------------
1/e2        1/e1             RX, TX       Active  No

What I Ended Up Doing About It

I was running tcpdump and fprobe processes on the network card attached to the destination port. I discovered that if I defined VLANs on that network card, and attached tcpdump/fprobe processes to the VLAN interfaces instead, everything worked.

Turning Off Port Monitoring

console(config)# interface ethernet 1/e1
console(config-if)# no port monitor 1/e2
console (config-if)# end
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