So this warning is triggered when a packet was received on a switch
port connected to another openflow switch, but there was no matching
flow entry for the packet and thus it was sent up to nox. The message
was initially logged with the thought that a packet would only reach
an "internal" switch port if its flow had been permitted by the
controller, in which case flow entries should have been installed in
all switches en route, and thus internal switch ports would not
receive non-matching packets.
That being said, the warning comes up fairly often for various reasons:
1. The naive flooding of broadcast packets without any installation
of flow entries results in the packets being sent up to the controller
by every internal switch port receiving them.
2. When a flow entry is first set up, there's a slight race condition
in that the first hop switch could have already set up its entry and
begun forwarding packets before the second hop has completed its
installation of the new entry. The second hop switch will thus
receive the packet, not see an entry for it, and thus send it up to
the controller for a permission check.
Neither of these occurrences however should result in any weird
network behavior as the packet should still get forwarded on as
expected.
Natasha
On Jul 16, 2008, at 11:05 PM, Glen Gibb wrote:
> Hi all,
>
> What would trigger a "Buffer_id xxx at internal ap" message?
>
> Thanks,
> Glen
>
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