[rbridge] Consensus Check: Configure ports to disable end stationtraffic

[Eric Gray]

Donald,

	The wording of this is ambiguous and the intention is 
therefore not clear.

	What it appears like people are arguing for is the option
to exclude - via configuration - any port from the flooding or
other broadcast/multicast traffic.  One reason for doing this 
might be that the network operator is certain that there are not
and never will be end-stations associated with this link.  This
is merely one reason.

	As I mentioned in response to James' comment, disabling
flooding, and forwarding of other forms of broadcast/multicast
traffic does not necessarily preclude attachment of many of 
today's end-stations (although disabling ARP responses would 
make it more difficult, as would bi-directionally disabling 
broadcast forwarding).

	Hence configuring a port to disable flooding for that 
port and configuring a port to say there are no end-stations 
is not exactly that same thing.

	Further, the proposed consensus is unclear on the scope
to which it might apply.  I assume that the intention is only
to apply this on egress from the RBridge domain onto a legacy
Ethernet link.  If this is the case, however, that should be
explicitly stated as part of the proposed consensus.

	However, even if this is the case, it clearly must be
the case that we are assuming no similar technology is also
connected to this same link - and the link is in fact a stub 
with respect to every VLAN with which it is associated - or
we face the situation in which we don't forward broadcast or
flooded messages some other technology relies on to discover
topological pathologies itself - in the event of accidental
connections.

	Also, the proposed consensus is unclear on the impact
that declaring a port as transit only would have on non-IP
multicast traffic

	Frankly, I believe the proposed consensus would be more
clear and acceptable if it implied less.  For example, I would
find something along these lines more acceptable:

"Forwarding of flooded and/broadcast frames on every port 
 associated with a VLAN, or every port in a LAN, except the
 port on which it was received is the default case. However,
 it is possible to preclude forwarding of this traffic for
 any port on which it is not required - via configuration,
 for example."

Naturally, this also would need to be explicitly defined to
apply only to RBridge egress.

	And even in this case, I have to wonder why we need to
say anything at all on this topic.  This strikes me as being
pretty much out of scope, since it relates to behavior that
does not impact RBridge interoperability in any way.

--
Eric Gray
Principal Engineer
Ericsson  

> -----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
> 
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