[rbridge] Consensus Check: Configure ports to disable end station traffic

[Eastlake III Donald-LDE008]

Hi,

Speaking as co-chair:

All "Consensus Check" messages that have been posted here are because
there was at least a rough consensus at a meeting and, per IETF
procedure, the consensus is being tested on the mailing list. It is then
the job of the working group chairs to judge the consensus of the
working group based on integrating the meeting and mailing list.

There were two distinct proposals presented in Vancouver, one of which
is outlined in the message below, and for which there was a consensus in
favor at the meeting.

The second was a specific proposal for point-2-point links between
Rbridges for which I will post a Consensus Check right after this
message. This second proposal specified fixed destination and source
addresses for a port so configured and the consensus at the meeting was
against it. There were several negative comments on the second proposal.

Sorry if the minutes are confusing on this point. If it is not too late
to change them, I'll try to clarify them.

Speaking as a member of the WG:

"End station traffic" below means all traffic except (1) TRILL Ethertype
frames and (2) link/media control frames (frames with a destination
address in the range 01-80-C2-00-00-00 to 01-80-C2-00-00-0F). An end
station on a link where all connectivity to the outside world is via one
or more Rbridges whose ports to that link are configured to disable such
traffic would be completely marooned. It seems likely that there would
be a MIB counter for end station frames received on a port that was
"disabled" for them but we haven't done any MIB work yet.

I was motivated to make this proposal when I recently read the
Architecture draft and was thereby reminded that the current TRILL
specification requires that all broadcast, unknown unicast, and
non-IP-derived multicast are output to every link. In a modern all
Rbridged 802.3 campus, one would expect that all links would be Rbridge
to end station or Rbridge to Rbridge. Thus, all such frames output on an
Rbridge to Rbridge link are completely wasted. The extent of the waste
would depend on the percentage of traffic of this type. While keeping
such traffic to a small percentage is generally desirable, there may be
networks where it is substantial, resulting in a substantial waste of
capacity on all Rbridge to Rbridge links. So I believe this capability
will be present in essentially all configurable Rbridges. Given this,
and the simplicity of the option, my personal opinion is that we should
provide for it.

In principle you could also disable TRILL traffic. But that does seems
like a bad idea. Disabling end station traffic incorrectly would just
maroon one or more end stations. Disabling TRILL traffic incorrectly can
lead to loops and traffic storms that could bring down part or all of
your network.

Donald

-----Original Message-----
From: rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org] On
Behalf Of Eastlake III Donald-LDE008
Sent: Monday, January 07, 2008 1:34 PM
To: Rbridge at postel.org
Subject: [rbridge] Consensus Check: Configure ports to disable end
stationtraffic

This is a check via the mailing list to confirm or refute an apparent
consensus at the Vancouver meeting taken from the minutes of that
meeting:

           Currently broadcast, unknown unicast, and
      non-IP-derived multicast frames are output to all links. This is
      wasteful if there are no end stations on the link. Provide that
      a port can be configured so as to be disabled for end station
      traffic.

If no particular controversy arises over this in the next three weeks,
We will declare it to be the working group consensus.

Thanks,
Donald & Erik