[rbridge] Consensus Check: Configure portstodisable endstationtraffic

[Caitlin Bestler]

Eric Gray wrote:


> 
> 	Also, the notion of "known to be on the inside
> of the network" is a trap people fall into if they were
> not listening to the discussion in this working group
> from 18 to 24 months ago in which the point was made on
> several occasions that the intended "topological" notion
> of "inside the network" is not actually topological at
> all.  Connect two links that appear to be "outside of the
> network" and they are now "inside of the network."  The
> apparent "connection" of two or more "outside links" is
> a normal occurrence during network startup.  Connection
> or disconnection of physical links is something that an
> operator may not have direct control over.
> 

If all that is required to have a "port known not to do X"
actually do X is for an operator to misconnect a cable then
I would agree that the RBridge (or Bridge) probably should
not be assuming that the cables were inserted properly.
That's just dangerous.

But there are specialized Bridges where such mis-configurations
are simply not physically possible. To cite one example, it is
common for Hypervisor's to offer (via a privileged domain such
as "Dom 0") a software switch that has internal ports leading
to virtual NICs associated with Guest Partitions and the actual
external Ethernet ports leading to the real world. No network
technician can accidentally plug a Virtual Machine into the
Ethernet Port, or vise versa.



> 	However, I agree that this is something that should
> be out of scope (avoiding these discussions entirely).
> And for mostly the same reasons.  But I also thought I
> said that already too...
> 

Agreed. The key is that we do no what any RBridge to be
forced to do something that is clearly not appropriate 
given its physical packaging solely because a poorly worded
paragraph made it a requirement even though there was no
actual benefit to any actual deployment.

These special configurations do not need explicit blessing
in the draft.

Not being anywhere near as familiar with core bridges as I
am with edge issues, I am still unclear as to whether "port
with no end stations" is an aspiration that a network administrator
would like to see (but for which there is no guarantee, and hence
equipment should not simply assume that the aspiration will be
met) or something inherent (it would be physically absurd
to connect end stations off a given link because it inherently
is a long-haul link outside the building, or somesuch).