Ethereal-users: RE: [Ethereal-users] capturing traffic on multiple vlans

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From: "Tamhankar, Arundhati" <Arundhati.Tamhankar@xxxxxxxxxxxx>
Date: Thu, 30 Oct 2003 16:31:17 -0800
Thanks a lot for your help. Ya, I guess an additional ethreal module may be
required for multiple vlan capture. 

regards,
Arundhati..

-----Original Message-----
From: Guy Harris [mailto:guy@xxxxxxxxxxxx]
Sent: Friday, September 19, 2003 2:11 PM
To: Tamhankar, Arundhati
Cc: 'ethereal-users@xxxxxxxxxxxx'
Subject: Re: [Ethereal-users] capturing traffic on multiple vlans



On Sep 19, 2003, at 10:29 AM, Tamhankar, Arundhati wrote:

> I wish to captire traffic on 2 vlans which go to a router. However I 
> can see
> traffic on just 1 vlan. I am connected to the router via a hub. Do I 
> have to
> make any changes in my ethereal config so that I can vew both the 
> vlans?
>
> I do not see a VLAN tag. I can see only 1 type (0x0800) which is IP.

You're probably capturing on a device that's bound to the VLAN from 
which you're seeing traffic, so it's forwarding only traffic on that 
VLAN, and doing so after removing the VLAN tag.

If you have more than one network device that shows up in the 
"Interface:" combo box, try capturing on one of the other ones *if* it 
sounds as if it's also a device for your NIC.

If that doesn't work, or if there's only one network device, you'd have 
to ask the WinPcap developers about this:

	http://winpcap.polito.it/contact.htm

It is not necessarily the case that you *can* capture raw traffic, 
rather than just traffic on your VLAN, on Windows.  (The BSDs, and 
Linux, might not have this limitation, as they create interface devices 
for the physical interfaces, in addition to possibly creating devices 
for VLANs.)