Last Call Review of draft-ietf-tsvwg-circuit-breaker-11
review-ietf-tsvwg-circuit-breaker-11-opsdir-lc-dunbar-2016-02-13-00

I have reviewed this document as part of the Operational directorate's ongoing
effort to review all IETF documents being processed by the IESG.
 These comments were written with the intent of improving the operational
 aspects of the IETF drafts. Comments that are not addressed in last call may
 be included in AD reviews during the IESG review. Document editors and WG
 chairs should treat these comments just like any other last call comments.



Major issue with the proposed approach:



Traffic continuously go from Ingress and egress.

If the Ingress and egress nodes don’t  have synchronized timers as SONET/SDH
(most packet routers/switches don’t have synchronized timer),
 the meters collected by both ends can’t be correlated  properly (i.e. they are
 meaningless).



The only ways for the meters on both Ingress and Egress to work reliably
(without synchronized timer) is via ECN, or via synthetic data (like
 IPPM).



For “Circuit Breaker based on RTP”, DPI has to be deployed to detect RTP if the
Ingress and egress nodes are the end points of tunnel (i.e.
 aggregated traffic). The approach is very expensive.



Minor issue:

Typos:



-



Page 5: The  paragraph before 1.1:

“Circuit Breaker has in fact being tripped”: do you mean “being triggered”?





Regards, Linda Dunbar