[mpls] Special purpose labels in draft-hegde-spring-traffic-accounting-for-sr-paths

[Greg Mirsky <[e-mail]>]

Hi Shraddha,
thank you for very well written and thought through draft. I have these
questions I'd like to discuss:

   - Have you thought of using not one special purpose label for both SR
   Path Identifier and SR Path Identifier+Source SID cases but request two
   special purpose labels, one for each case. Then the SR Path Identifier
   would not have to lose the bit for C flag.
   - And how you envision to collect the counters along the path? Of
   course, a Controller may query LSR for all counters or counters for the
   particular flow (SR Path Identifier+Source SID). But in addition I'd
   propose to use in-band mechanism, perhaps another special purpose label, to
   trigger the LSR to send counters of the same flow with the timestamp
   out-band to the predefined Collector.
   - And the last, have you considered ability to flush counters per flow.
   In Scalability Considerations you've stated that counters are maintained as
   long as collection of statistics is enabled. If that is on the node scope,
   you may have to turn off/on the collection to flush off some old counters.
   I think that finer granularity, per flow granularity would be useful for
   operators. Again, perhaps the flow itself may be used to signal the end of
   the measurement and trigger release of counters.

Regards,
Greg