Re: [vserver] transient network drops

From: Eugen Leitl <eugen_at_leitl.org>
Date: Sat 01 Sep 2007 - 10:30:39 BST
Message-ID: <20070901093039.GJ12988@leitl.org>

On Sat, Sep 01, 2007 at 02:31:47AM +0200, Herbert Poetzl wrote:

> well, most likely, spanning tree is the magic word here :)
>
> (http://en.wikipedia.org/wiki/Spanning_tree_protocol)

I use spanning tree since my firewalls are redundant (STP
disables one firewall, which gives you a poor man's
failover capacity -- sure no carp+pfsync).

However, in this case the outages are intermittant, and what
happens is every couple hours or so the switch suddenly notices
a packet with a MAC which used to be on port 6 suddenly comes
in at port 49, at which point it ignores anything with that
MAC on port 6 until the period of MAC aging expires, and it
decides it's been port 6 after all.

So why would

        switch-1 (level 3)
         | |
        NIC1 |
        system |
        NIC2 |
         | |
        switch-2 (level 2)

do that? Notice that the system doesn't route. It all
happens at Ethernet frame level.

-- 
Eugen* Leitl leitl http://leitl.org
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Received on Sat Sep 1 10:37:57 2007
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