| 2012-11-13 |
Nov 2012 Planery |
Note that 802.1AS does not currently define “listener only” systems. Instead, it indicates that a time-aware system may or may not be grandmaster-capable. But, a time-aware system that is not grandmaster capable may hav more than one port.
It appears that, when the commenter talks about a "listener-only" system, the commenter is referring to a time-aware system that is not grandmaster-capable and has only one port. It is true that for this case some of the requirements are not applicable. However, 802.1AS does not specifically consider this special case. IEEE 1588 does talk about "slave-only" clocks, and in 1588 these have just one port, but that is because 1588 has not introduced the notion of a boundary clock that is not GM-capable but has many ports. (The fact that 802.1AS has introduced such a device is ok becauase 802.1AS uses an alternate BMCA, not the 1588 default BMCA.) The question here is whether 802.1AS should specifically distinguish the requirements for single-port devices that are not grandmaster-capable.
In any case, this could certainly be addressed, though it belongs in 802.1ASbt (i.e., the amendment) rather than the corrigendum. This is not a bug fix.
Since the other AVB standards do talk about “listener-only” systems, it could be helpful, and more friendly, to the user if 802.1AS also described this case
Defer, Technical review of possible feature addition to P802.1ASbt
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Technical experts review |
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