Hi Acee,
Acee Lindem wrote:
Speaking as WG member:
I am not opposed to this capability. However, I'm not sure if it justifies
taking two of the remaining router bits. The Router-Information LSA (RFC 4970)
is really the place for advertising capabilities.
We understand this concern and are in the process of drafting a
new revision that moves the "S" bit to the RI opaque LSA. Note,
though, that the definition of the Router Informational
Capabilities TLV in RFC 4970 explicitly says "...the informational
capabilities advertised have no impact on the OSPF protocol's
operation..." so we're defining a new "operational capabilities"
TLV to hold this and any future "important" bits.
It would be ideal if this could be done without an implicit backward compatibility mechanism. Doing an election just to see if all routers in the area are able to recognize the R-bit is complexity that would be nice to avoid. The draft recommends both setting the R-bit and advertising any transit links with 0xffff cost. Hence, It would be an odd topology where the differences in R-bit capability could cause a routing loop. Unfortunately, it is possible to draw one if you there is a valid path to a destination D, and that destination is accessible via multiple routers with varying R-bit capabilities :^(.
It would be nice, but I don't see any alternative that can be
guaranteed to be correct for all topologies.
Thanks,
Paul
Thanks,
Acee
On Apr 16, 2010, at 4:44 PM, Acee Lindem wrote:
At the OSPF WG meeting in Anaheim, the subject draft was presented and there seemed to be some interest in such a capability (similar to the overload bit in ISIS). Please indicate whether or not you support making this draft a WG document.
http://www.ietf.org/id/draft-pillay-esnault-ospf-rbit-00.txt
Thanks,
Acee - (as OSPF WG Co-chair)
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