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[802.3_NGAUTO] comments 139 & 169 (late)

These comments are about making sure our state diagrams result in interoperable 100ms startup.  We had a problem which showed up in 10GBASE-T interoperability plugfests where we didn't have times enforced for the SILENT and TRAINING states, and one vendor might take longer than another in the SILENT state, leaving the other without enough time to train in the other state.  This hole was plugged by a 'recommended' timing put in in 802.3az, but that was a patch - we shouldn't repeat it.
So, the gist of these comments are the same - incorporate the 100msec timing objective into the timing in the PHY control state diagram.

Initially, comment 169 proposed 2 timers, and we worked a solution around that (you'll see it in the proposed responses), BUT, just after Natalie posted, Alireza and I had a quick discussion.  Alireza pointed out that we already have the link_fail_inhibit_timer, which kicks us out of startup (both in Figure 149-32 and in Figure 98-7 if auto-neg is used).  So, we really only need one timer, for the silent state (which really only applies to the slave if you look at the state diagram).  That makes things really easy, as opposed to the published solution, which has 2 timers, not really so hard, but definitely a bigger change, and one with a redundant timer & transition.

With this change, the response would now be:

P154 L39 Add the following definitions to, before minwait_timer:


                A timer used to determine the maximum amount of time the PHY Control stays in the SILENT state. This timer shall expire 40 msec after being started.

In Figure 149-33

Insert "start max_silent_timer" to the SILENT state

Add arc exiting SILENT state and re-entering SILENT state with condition "max_silent_timer_done"

Editorial license to conform to IEEE 802.3 style.

I'd like to hear any feedback so we can have a consensus position.


George Zimmerman, Ph.D.
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications

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