port mirroring with SRW2048

Unanswered Question
Sep 6th, 2010

I have a workstation on this switch that is running WireShark and I need to get packets to it.  However the moment I turn on port mirroring the station loses IP connectivity to the network.  I tried Rx only, Tx only and both and all three settings knock the workstation off the IP network.  Is there something I am missing?

Also, I noticed that I can only mirror 4 source ports to this one target port.  I would like to select pretty  much all the ports as source port.  Why can't I do this?  I was previously using an older DLink switch that allowed me to mirror all ports and I am pretty sure that other switches like the Cisco 2900 series let you select all ports as source ports.



I have this problem too.
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Joachim Kern Tue, 09/07/2010 - 08:41

The limit of 'source' ports to mirror is a restriction of the switch (probably also depends on underlying chipset being used).

However depending on your testing it does not really  make sense to mirror many ports as you will loose traffic. One 'source' port will copy and forward all packets on the TX and RX line to the 'sink' port's TX line. So you potentially overrun the 'sink' with only one mirror (if both ports have the same speed)

Loosing Ip connectivity on the mirror target port is normal i guess. You will only receive the frames the 'source' ports are forwarding to the 'sink' port.


DIEGO ALONSO Tue, 09/07/2010 - 14:36

I fully understand what you are saying but that isn't consistent with previous experiences with port mirroring.  I have used Cisco Catalyst type switches and also DLink switches that allow you to mirror all ports on the switch to one destination port.  And even with all ports mirrored IP connectivity to the destination port is maintained. 

This is not so surprising on the Catalyst stuff which is considered maybe a bit more "high end" than Linksys but the DLink which is a cheaper switch has the ability to do this just as the Catalyst.  It seems that the Linksys is inferior in this regard to the Catalyst and the DLink.

Sorry to hear that and hopefully a future firmware version will change this behavior.

Thank you very much for your help.




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