[rbridge] MUST not send spanning tree BPDUs?

[Joe Touch]

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Donald Eastlake wrote:
> Hi,
> 
> I'll go ahead and change the draft, since that seems to be what most
> people want. But I don't consider it that big a deal for the following
> reason:
>        If you wanted to send BPDUs despite the current prohibition,
> you would just say that you are implementing a virtual bridge
> connected between the RBridge port and the link. That way of thinking
> about it makes it crystal clear that RBridges don't participate as a
> single node in spanning tree.

FWIW, this is the reason for the MUST NOT. I was a proponent of
basically the perspective above; that an rbridge was a device distinct
from a bridge that was compatible with bridges, not a superset of their
functionality per se.

Joe

> On Sun, Nov 30, 2008 at 12:00 AM, Dinesh G Dutt <ddutt at cisco.com> wrote:
>> I strongly agree with dropping the sentence and adding the "MUST NOT
>> forward" piece,
>>
>> Dinesh
>> Radia Perlman wrote:
>>> Yeah. I think we should either drop the sentence, or say "MAY generate
>>> BPDUs,
>>> but MUST NOT forward BPDUs from
>>> one link to another".
>>>
>>> Radia
>>>
>>> Donald Eastlake wrote:
>>>
>>>> Hi Radia,
>>>>
>>>> See below...
>>>>
>>>> On Fri, Nov 28, 2008 at 6:31 PM, Radia Perlman <Radia.Perlman at sun.com>
>>>> wrote:
>>>>
>>>>> The spec currently says (in section 4.7.3.3 Transmission of BPDUs)
>>>>>
>>>>>  RBridges MAY support a capability for sending spanning tree BPDUs for
>>>>>  the purpose of attempting to force a bridged LAN to partition as
>>>>>  discussed in Section A.3.3.  Except for this optional capability,
>>>>>  RBridges MUST NOT send spanning tree BPDUs.
>>>>>
>>>>>
>>>>> I don't remember any discussion on saying that RBridges MUST NOT send
>>>>> BPDUs. I remember
>>>>> at one point requiring it, and saying that an RBridge is DRB if and only
>>>>> if it is the Spanning tree Root.
>>>>> (I still would prefer that, by the way -- makes all the controversial
>>>>> per VLAN Hellos
>>>>> unnecessary).
>>>>>
>>>>> I remember it being removed from the spec (because of complexity with n
>>>>> versions of
>>>>> spanning tree, and links with no bridges, perhaps, where the spanning
>>>>> tree messages would
>>>>> be unnecessary overhead), but I don't remember any reason to say
>>>>> RBridges MUST NOT sent
>>>>> BPDUs.
>>>>>
>>>> I suspect it used to say "do not" in the sense that there is no
>>>> RBridge reason for an RBridge port to send spanning tree BPDUs except
>>>> for the optional bridge LAN partitioning feature described in Section
>>>> A.3.3. In some pass to upgrade to IETF implementation key words, it
>>>> probably got changed when it didn't necessarily need to be. The only
>>>> problem I can see with dropping this is that it might marginally
>>>> increase the chance someone would erroneously try to build spanning
>>>> trees through an RBridge.
>>>>
>>>> Donald
>>>>
>>>>
>>>>> Anyone else remember?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Radia
>>>>> _______________________________________________
>>>>> rbridge mailing list
>>>>> rbridge at postel.org
>>>>> http://mailman.postel.org/mailman/listinfo/rbridge
>>>> =============================
>>>>  Donald E. Eastlake 3rd   +1-508-634-2066 (home)
>>>>  155 Beaver Street
>>>>  Milford, MA 01757 USA
>>>>  d3e3e3 at gmail.com
>>>> _______________________________________________
>>>> rbridge mailing list
>>>> rbridge at postel.org
>>>> http://mailman.postel.org/mailman/listinfo/rbridge
>>> _______________________________________________
>>> rbridge mailing list
>>> rbridge at postel.org
>>> http://mailman.postel.org/mailman/listinfo/rbridge
>> We make our world significant by the courage of our questions and by the
>> depth of our answers.                               - Carl Sagan
> =============================
>  Donald E. Eastlake 3rd   +1-508-634-2066 (home)
>  155 Beaver Street
>  Milford, MA 01757 USA
>  d3e3e3 at gmail.com
> _______________________________________________
> rbridge mailing list
> rbridge at postel.org
> http://mailman.postel.org/mailman/listinfo/rbridge
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