Erik,
This means that the STP-running sub-cloud need to be P-bit transparent, right?
Yes, that is my understanding. I think the draft is consistent with this. That is, a ND proxy implements either the P-bit (choice a) or the STP (choice b) modes, but not both. In STP mode the P-bit (or any of the other bits in the RA) isn't touched.
Thus if there is an upstream which sets the P-bit, then any downstreams from the sub-cloud should receive the P-bit.
To do that the ndproxy nodes which run STP need to behave quite differently than then ones that don't run STP. What are the exact rules for them?
Are they
- ignore any P-bit
- make sure any RAs that are received with the P-bit set are proxied (transmitted) with the P-bit
Right, and I think that is the defined behavior of a proxy implementing STP (i.e., they pass the P-bit setting through unchanged).
I think it would be good if another paragraph was added to Section 4.1.4.3 "ICMPv6 Router Advertisements" that clarifies this behavior. Also, something added to Section 6. "Loop Prevention" that explains the case of a site with a mixture of proxies.
Thanks, Bob
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