[rbridge] Consensus Check: Configure ports todisable end stationtraffic

[James Carlson]

Eric Gray writes:
> 	However I disagree that ARP failure is a specific intent
> of the configuration option mentioned in Donald's "consensus
> check" or that this is sufficient to somehow "enforce" a network
> operator's intention that a link should remain "end-station free."
[...]
> 	Hence configuring an RBridge to disable certain types of
> presumed wasteful traffic forwarding on a link is orthogonal to 
> indentifying that link as end-station free.

I don't think it's quite orthogonal.  The two are related in that if
you "optimize" away this "wasteful" traffic, you necessarily also
break the operation of any ordinary end stations that may be present
on that link, as Joe Touch was correctly pointing out.  Those nodes
can't work normally, so you're already partway down the path to
breaking those nodes intentionally.

But fair enough to observe that there are two different intents here.
I think Anoop was arguing more forcefully in favor of having a more
generic (and thus simpler) "no end-station on this link" option on the
theory that some links may be "known" (by an administrator) to be on
the inside of a network, and thus optimizing all of the end-station-
related behavior away would be useful for some implementations.

It seems particularly attractive given that TRILL wants to encapsulate
things.  If we were "only" bridging, this wouldn't be an issue.

I'd be ok with either intended option, but would slightly prefer not
bothering to document this special link behavior, as it looks to me to
be the sort of enhancement that vendors could cook up on their own
without affecting either TRILL interoperability or ordinary RBridge
operation.  It's not something I think is strictly _needed_ in the
TRILL document in order to make it complete ... though it seems Anoop
does.

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
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