Linux Ethernet Bridging - Apr 2007 - [Bridge] Adding same physical port to multiple bridges

Hi,

Is there any particular reason why the same physical port cannot be 
added to multiple bridges? Is it because of STP?

If I am not using STP - can I change the code to have the same physical 
port in 2 VLANs? Is that a safe change?

Thanks,
Abhijit

On Tue, 27 Jan 2004 17:10:43 -0800
Abhijit Kumbhare <abhijitk@nortelnetworks.com> wrote:
> Hi,
> 
> Is there any particular reason why the same physical port cannot be 
> added to multiple bridges? Is it because of STP?
Not just STP, but all the data structures in the code are set up
1-N.  For example, there is a pointer in the netdevice structure that
contains the bridge to handle the received packet.  What would it mean
to be part of multiple bridges? Would received packets be process N times
by each bridge? 
> If I am not using STP - can I change the code to have the same physical 
> port in 2 VLANs? Is that a safe change?
Probably not. What are you trying to do?  Might to be bridge the
physical LAN and do any filtering based on tag using bridge-filtering
(ebtables).

-- 
Stephen Hemminger 		mailto:shemminger@osdl.org
Open Source Development Lab	http://developer.osdl.org/shemminger