[rbridge] VLAN mapping anonmolies...does anyone care?
Radia.Perlman at Sun.COM
Sat Dec 12 15:12:31 PST 2009
A couple of things to bring to people's attention in fewer words than
reading the VLAN mapping draft. :-)
a) if mappings are not invertible, as in, both VLAN A and VLAN B in East
map to VLAN C in West,
then it's not clear what to map VLAN C to, when forwarding from West to
I'd say either make that a configuration error and don't let someone
configure two VLANs that map
to the same thing, or say that when mapping from (West, VLAN C), if both
A and B from East map to (West, C),
then map to the highest VLAN number, or the first one listed in the
mapping configuration table. Other
b) if mappings are not invertible, same example as a). and the path goes
from East to West and then East
again, VLAN A in East might wind up getting mapped to VLAN B in East.
I don't care -- I think noninvertible mappings should be illegal.
c) another form of noninvertible mapping is (East, VLAN A : West, null),
meaning that VLAN A in East
should be dropped instead of being forwarded to cloud West. The
surprising result of this, if the path
goes from East to West and back to East, is that VLAN A might become
partitioned as a result.
I don't care, especially since I can't think of any good, simple
solution to this.
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