Wireshark · Ethereal-users: Re: [Ethereal-users] Re: 802.1p packet marking / detection

[Joerg Mayer <jmayer@xxxxxxxxx>]

On Sat, Dec 04, 2004 at 11:06:34AM -0600, Chris T. wrote:
> I read the FAQ and I am not sure I completly understand what they are 
> saying. I had the following setup. A mitel phone plugged into a netgear hub 
> which was then plugged into a cisco switch setup with trunking on the port. 
> The phone is supposed to mark the packets with CoS 6 and vlan 102 this is 
> what I am trying to verify. I then took my laptop with ethereal and plugged 
> it into the hub made a call captured some packets and I don't see the 802.3 
> frame at all where it would be marking the packet as priority 6 or VLAN 102. 
> I wouldn't think the hub would strip anything off the phone 's packets since 
> it is a dumb hub.
> 
> Am I doing something wrong or missing something here?

Not necessarily. you may try a few things:
a) capture with the capture filter "vlan" (see man tcpdump to find out what
   this does)
b) make sure that the supposed hub truly is a hub and not a dual-switch hub
   or something even more clever (the first minihub I ordered turned out to
   be a switch after all)
c) make sure your network card isn't doing some very clever things with vlans
   (vlan offloading) - this is a problem I have with my Intel e1000 - it always
   hides the vlan stuff from me - so I have to use my ne pcmcia 10 MBit card to
   actually see the vlan header instead of the "net ethernet" frames.

    Ciao
        Joerg
-- 
Joerg Mayer                                           <jmayer@xxxxxxxxx>
We are stuck with technology when what we really want is just stuff that
works. Some say that should read Microsoft instead of technology.