tcpdump on VLAN interface not working ..?

[Klaus Turina <klaus.turina () ericsson com>]

Hi all,
I experience the following effect and couldn't find any hint what I'm doing wrong un using tcpdump.
So maybe it's a bug? Or a known limitation? Or ????

It is the following.

On a 10GE interface I have VLAN tagged traffic let's say with VLAN ids 1 and 2 on interface eth0

So I defined 2 virtual interfaces eth0.1 and eth0.2 to filter the traffic I'm interesting in from all the other 'noise' 
on the fiber.

If I look at the interfaces using ifconfig I see the Rx packet counter increasing as expected on the physical eth0 
device and on the virtual eth0.1 and eth0.2 devices.
So far so good.

But when I setup
tcpdump -i eth0.1
I get 0 captured packets.

On the other hand if I set up
tcpdump -I eth0 vlan 1
I get the expected packets.

However since I have multiple tcpdump processed running on the eth0 vlan 1 and vlan 2 traffic wanted to used the 
virtual device for performance reasons.

Any idea what is wrong using -I eth0.1 ?????

Thanks
Br
Klaus


KLAUS TURINA
Senior Specialist - Principal Systems Designer

Ericsson GmbH; Eurolab R&D
EDD/XLS
Ericsson Allee 1
52134 Herzogenrath, Germany
Phone +49 2407 575 692
Fax +49 211 575 477
Mobile +49 173 2594193
Klaus.Turina () ericsson com
www.ericsson.com


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