[Roll] NSA PS-set metric/constraint

[Rahul Jadhav <[e-mail]>]

Hello Authors of NSA extn and all,

One more question in the context:

The draft adds new routing metrics/constraints (PS set) nested as part
of the NSA parent metric.

My question is with regards to what happens if this routing metric is
used outside of the CAOF. Any metrics/constraints could be used by any
OF and thus PS set metric defined by the draft can be used by other
OF.

RFC 6551 says that if the metric is not understood by the node and if
it is a 6LR then it may not process it but it has to propagate it.
Unlike other metrics, the PS set metric in this case contains
link-local values that cannot be used beyond link-local. As such upon
propagation, any downstream 6LR that understands the PS set metric
would use the information and get impacted adversely.

Should we tie the PS set metric to CAOF specifically in the draft, in
which case this problem won't be there? Or we can specify this issue
as it is for the readers to understand the problem if the PS set is
used outside of the CAOF. Either way works for me.

Best,
Rahul