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Subject: RE: [PATCH] (3/4) bridge linkstate handling
Date: Thu, 29 Jul 2004 11:11:02 -0400
Message-ID: <C0170D0AF1277849A4B4518034F855DD0CFC3A@aiexchange.ai.aiinet.com>
Thread-Topic: [PATCH] (3/4) bridge linkstate handling
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From: "Eble, Dan" <DanE@aiinet.com>
To: <hadi@cyberus.ca>
Cc: "Stephen Hemminger" <shemminger@osdl.org>, <bridge@osdl.org>,
        <netdev@oss.sgi.com>
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> -----Original Message-----
> From: jamal [mailto:hadi@cyberus.ca] 
> 
> On Thu, 2004-07-29 at 09:24, Eble, Dan wrote:
> > Even if STP were implemented in user space, this part 
> should be done in
> > the kernel to make sure that there is no window of time for 
> a packet to
> > be received or transmitted after the link state changes.  
> 
> Your main problem there would be STP convergence time. Transfering the
> packet to user space and reacting should be several factors 
> of magnitude
> faster than it takes STP to converge.
> The STP state should stay in the kernel. Control of it and 
> BPDU handling
> is what i am suggesting to take out.

Is the time it takes STP to converge really the issue in this case?
When a port loses and then regains carrier, it needs to enter the
Blocking state without delay.  If the carrier state change were handled
by a daemon, the bridge driver would have some time to transmit or
receive packets via that port before the daemon could tell it to block
the port, wouldn't it?