Ethereal-users: RE: [Ethereal-users] port mirroring disables browsing

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From: Joe Elliott <joe@xxxxxxxxx>
Date: 01 Nov 2005 07:14:30 -0800
Hello Elliott,
      In the old days you could transmit on mirror ports on the Cisco units. Newer versions of the IOS set the port to read only.

I assume this is in response to customers accidentaly sending bogus traffic with workstation based sniffers. It forces you to use a dual homed system.

This is only my experience and may be different on other vendors equipment.

Hope this helps ... Joe.

-----Original Message-----
From:  Carte, M Elliot
Date:  11/1/05 6:48 am
To:  ethereal-users@xxxxxxxxxxxx
Subj:  [Ethereal-users] port mirroring disables browsing

Sorry if this is a stupid question. I'm using a Dell PowerConnect 2708
and mirroring the uplink port (port 1) to port 8. I then use a laptop on
port 8 to monitor traffic on the switch with Ethereal. However, when I
do this I can no longer reach the default gateway (access Internet) from
the laptop (monitoring port). If I try before I even start Ethereal, I
still can't, so it must be the port mirroring. Does anyone know why this
would be? Can you not send and receive your own packets when you're
monitoring another port? Does this happen on other switches, or is it
switch-specific? Thanks in advance.

-elliot



M. Elliot Carte

UITS - DMNS

office: 317.274.5843

cell: 317.840.1729

mecarte@xxxxxxxxx <mailto:mecarte@xxxxxxxxx>