Ethereal-users: [Ethereal-users] Possible Bug for 802.1Q Tagging

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From: Brent Witcher <bwitcher@xxxxxxxxxxxxxxxxxx>
Date: Thu, 03 Nov 2005 15:40:15 -0600

Anyone seen problems capturing packets with a 802.1Q header? I am seeing I think what was reported in BugID-184. It was dismissed as 'working' but it doesn't appear to working.

Problem is when the "VLAN" capture filter argument is used, all 802.1Q packets are indeed captured; but when "VLAN xxx" is used, only packets with 'Priority: 0' are captured. Am I missing something basic?


Examples:
(Using Ethereal GUI results in same behavior; I removed the surrounding packet data for brevity.)

Using the following command: 'tethereal -V vlan'
the 802.1Q headers are as follows...
--
802.1Q Virtual LAN
    110. .... .... .... = Priority: 6
    ...0 .... .... .... = CFI: 0
    .... 0011 0010 0000 = ID: 800
--
802.1Q Virtual LAN
    000. .... .... .... = Priority: 0
    ...0 .... .... .... = CFI: 0
    .... 0011 0010 0000 = ID: 800


Using this command: 'tethereal -V vlan 800'
results in ONLY packets with the Priority of zero.

--
802.1Q Virtual LAN
    000. .... .... .... = Priority: 0
    ...0 .... .... .... = CFI: 0
    .... 0011 0010 0000 = ID: 800
--
802.1Q Virtual LAN
    000. .... .... .... = Priority: 0
    ...0 .... .... .... = CFI: 0
    .... 0011 0010 0000 = ID: 800


Regards,
Brent