[rbridge] suggested minor tweak to align TRILL documents

[James Carlson]

I-D protocol-11 says this on page 35:

   6. If the sender is DRB, the Rbridges (including itself) that it
      appoints as forwarders for that link and the VLANs for which it
      appoints them.

Note the "including itself" phrase, which indicates that the list must
be explicit.  I-D isis-02 says this:

      An RBridge's nickname may occur as appointed forwarder for
      multiple VLAN ranges within the same or different Port Capability
      TLVs within a DRB's Hello. In the absence of appointed forwarder
      subTLVs referring to a VLAN, the DRB acts as the appointed
      forwarder for that VLAN if end station service is enabled.

Note the "in the absence of" clause.  This latter spec would allow a
sender to omit any cases where the AF is the DRB, potentially omitting
the option entirely if all AFs are the DRB.  This seems a lot more
reasonable to me than the -11 language, which requires a "dummy"
option for the most obvious case.

This is especially so, as there's really nothing useful that anyone
else listening to this message could garner from hearing the DRB
appoint itself as AF.  Those other (non-designated) RBs need to hear
if they're being tapped as AF, but they don't need to do anything if
the DRB is AF.

Any chance we can update the protocol-11 language to conform to the
isis-02 text?  Suggestions would be either:

   6. If the sender is DRB, the Rbridges (excluding itself) that it

or:

   6. If the sender is DRB, the Rbridges that it appoints as
      forwarders for that link and the VLANs for which it appoints
      them.  Where the appointed forwarder is the DRB, the VLANs need
      not be listed explicitly.

(I like the former better, as it makes the expected result more
obvious, but the latter works, too.)

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