On Wed, 15 Aug 2007 11:27:42 +0300
"Vassil Panayotov" <vassil.panayotov@xxxxxxxxx> wrote:
> Hi,
> > In a redundant setup (2 bridges), I usally set the path cost of external ports
> > to 1 und internal ports to 100. So that the external port of the backup bridge
> > is in forwarding and the internal port in blocking state.
> >
>
> If my understanding of STP is correct you can achieve the same result
> by setting port priorities on the designated bridge's ports.
>
> > But, when the physical link goes down and comes back up (i.e. link failure or
> > cable unplug and replug) the path cost of the links automatically reset to
> > values like 4 and 19.
> >
> > Is this a desired behaviour, shouldn't the path cost remain at the values specified?
The current code doesn't keep track of dynamic versus user set values.
> IMO this is the desired behaviour - the port path cost is recalculated
> every time when link state change is detected, probably to accommodate
> to possible link speed change.
Yup.
> > I'm using bridge support in Kernel 2.6.19. As I can't test a new Kernel yet, I'm
> > just asking if this might be a bug and maybe someone knows if this has been
> > fixed lately?
> >
> > Thanks in advance.
> >
> > Best,
> >
> > Lars
>
> I am by no means an expert in the bridging code(and in kernel coding
> in general) but it seems that the "fix" bellow will "solve" your
> problem. But this is definitely not the right way to do it :)
>
> Regards,
> Vassil
>
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -89,9 +89,6 @@ static void port_carrier_check(void *arg)
> goto done;
> br = p->br;
>
> - if (netif_carrier_ok(dev))
> - p->path_cost = port_cost(dev);
> -
> if (br->dev->flags & IFF_UP) {
> spin_lock_bh(&br->lock);
> if (netif_carrier_ok(dev)) {
The automatic path_cost is a feature. If you want to set priorities, use
that feature instead.
--
Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx>
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