[Bridge] bridge problem when one interface is in blocking mode

wang dengyi dy_wang at yahoo.com
Thu Aug 30 08:28:45 PDT 2007


--- Stephen Hemminger
<shemminger at linux-foundation.org> wrote:

> On Wed, 29 Aug 2007 14:27:44 -0700 (PDT)
> wang dengyi <dy_wang at yahoo.com> wrote:
> 
> > --- Stephen Hemminger
> > <shemminger at linux-foundation.org> wrote:
> > 
> > > On Thu, 23 Aug 2007 11:17:44 -0700 (PDT)
> > > wang dengyi <dy_wang at yahoo.com> wrote:
> > > 
> > > > Hi Stephen,
> > > > 
> > > > Here is the detail
> > > > kernel version: 2.6.14
> > > > architecture: PPC
> > > > ehternet: from the processor mpc5200b
> > > > wifi manufactor: Netgate 5004 MP, Atheros
> chipset
> > > > wifi driver: madwifi 0.91
> > > > WDS on wifi: enabled.
> > > > 
> > > > I guess it's an issue combined by ethernet
> > > driver/wifi
> > > > driver and bridge. Is there anything you
> suspect
> > > that
> > > > I can check? 
> > > > 
> > > > I believe the 2 actions: updating forwarding
> > > database
> > > > when a stp package is received and delivering
> the
> > > > package based on the forwarding database, are
> > > correct.
> > > > I must miss something. For example, STP
> detection
> > > set
> > > > an interface as blocking and remove it from
> the
> > > > forwarding database? It's just my wild guess. 
> > > > 
> > > > By the way, I found Bartek reported the same
> issue
> > > on
> > > > 2.6.11.12 and 2.6.13.2. Here is the link:
> > > >
> > >
> >
>
https://lists.linux-foundation.org/pipermail/bridge/2005-October/004710.html
> > > > He has 3 ethernet nic for each machine and his
> fix
> > > is
> > > > to update the forwarding database only when
> the
> > > port
> > > > is in learning or forwarding state.
> > > >
> > > 
> > > There was a bug fix in later kernel (2.6.19)
> that
> > > causes the forwarding
> > > database to be purged when STP decides not to
> use
> > > interface.
> > > 
> > 
> > Hi Stephen, 
> > 
> > I merged the bridge code from the kernel source
> tree
> > 2.6.19. But it's the same thing: packages are sent
> > through the blocking interface. Anyway, I am
> worried
> > that something is missing when I merged the code.
> > Could you give me more information about the
> patch? If
> > it's possible, please send me  your patch for
> 2.6.19?
> > Thank you very much. 
> > 
> > At the same time, I am looking for the
> relationship
> > between blocking interface and the forwarding
> table
> > from the stp source code. No luck until now. Any
> hint?
> > 
> > 
> 
> Perhaps you are getting packets in over the blocked
> device,
> and they are getting into the forwarding table?
> 
> -- 
> Stephen Hemminger <shemminger at linux-foundation.org>
> 

The answer is yes and no. We do receive packets from
the blocked device. But they are BPDU packets only. 
The fowarding database is updated because the BPDU
package is received. 

Here is the chart of our network.

          +-------------+   
ath0  +---+   bridge 1  +---+ eth0
      |   +-------------+   |
      |                     | 
      |                     | 
      |   +-------------+   |
ath0  +---+   bridge 2  +---+ eth0
          +-------------+    
Both bridge has the same Mac address as the ath0. And
ath0 on the bridge 1 is blocked. So when the BPDU
packet is received on the ath0 of bridge 1, it update
the forwarding table and the following network packets
will go through the ath0 which is in blocking mode. 

Regards,

Dengyi


       
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