Requested revision
Standard: | IEEE 802.1Q-2011 | Clause: | 32; 33 |
Clause title: | Congestion notification protocol; Encoding of congestion notification Protocol Data Units |
Rationale for revision
There is an inconsistency regarding the polarity of cnmQOffset that can cause interoperability problems. Table 32-4, says that cnmQOffset is the inverse of cpQOffset. In that case, cnmQOffset would be positive when the queue is over the set point. 33.4.5 says that cnmQOffset is the same as cpQOffset. As for cpQOffset, a negative value indicates congestion. In 32.14.4, a Reaction Point is enabled only if cnmQOffset is negative (agrees with 33.4.5, not Table 32-4).
Proposed text
Either Table 32-4 or both 33.4.5 and 32.14.4 need to change. I’m not sure at this point which is best as I’m aware of at least one implementation that follows each. Discussion is needed on which correction is less disruptive.
Impact on existing networks
The current situation prevents interoperability. A change will mean some devices need to make a change to comply but will resolve the interoperability issue.
Originator
Name: | Pat Thaler | Email: | pthaler@broadcom.com<mailto:pthaler@broadcom.com> |
Affiliation: | Broadcom | ||
Submitted: | 2014-05-12 |