[rbridge] Tie breaking in trees

[James Carlson]

Anoop Ghanwani writes:
> Likewise, since we compute a tree for multicast, it
> would make sense to only allow one of those.

Yep; that's what has to happen.

> If someone really wants to have the multiple links
> active, then they can use link aggregation.

The only significant problem with that assertion is that it assumes
that the links are of a sort that can be aggregated.  I know that the
initial deployments (ours included) will all be TRILL-over-Ethernet,
but I do think it's a bad idea to assume that this will _always_ be
true.  Protocols (good ones at least) tend to have long lives, and
need to adapt.

(A minor problem is that handling aggregation by LACP is a pain.  It
requires manual configuration and maintenance.  If we detect and
handle aggregates appropriately in TRILL, then that's one more selling
point for RBridges over regular bridges: you just wire them up, and
they work.  No questions asked.)

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
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