Ethereal-users: Re: [Ethereal-users] voip

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Sun, 22 Aug 2004 04:41:02 -0700
brentb2 wrote:

does ethereal support 802.1p  and 802.1q   capture

What do you mean by "802.1p and 802.1q capture"?

I think at least some OSes, when a network interface is on a VLAN, will have two separate OS-level devices for the interface - one "raw" interface for packets delivered to the machine's MAC address and one "VLAN" interface for packets tagged for the VLAN the interface is on.

If you capture on the "raw" device (if the OS supports that), it might capture all packets sent to the machine's MAC address, as well as broadcast and multicast packets, and, for VLAN-tagged packets, might deliver the packets complete with the VLAN header. If, however, the interface supports VLANs itself, rather than leaving it up to the driver and other parts of the networking stack on the host OS, you might not be able to capture on the "raw" device, if it even exists.

If you capture on the "VLAN" device, you might see only packets on the VLAN the interface is on, and it might remove the VLAN header from the packets.

I don't know which OSes do that, if any, nor, if any do, do I know what the names for the devices in question are.