On 6/7/17, 10:38 AM, "Richard Cochran" <richardcoch...@gmail.com> wrote:
On Wed, Jun 07, 2017 at 02:46:39PM +0000, Rodney Greenstreet wrote:
> > Thank you for your feedback. I want to explain why we chose to add TAB
to your BC implementation rather than adding a new type of device. A TAB is
mathematically equivalent to a TC but is functionally equivalent to a BC. More
specifically, a TAB has the following BC attributes:
> > - A TAB participates in the BMC selection.
> > - A TAB has port state.
> > - A TAB has a separate logSyncInterval dataset member for
each port.
> >
> > It’s the last point that I think needs further clarification.
> Sure, there is a per-port value, but this is only relevant when the
> port becomes the GM.
Please read clause 10.6.2.3 ‘time-synchronization event message transmission
interval’ and clause 10.6.2.4 ‘Interval for providing synchronization
information
by ClockMaster entity’. The last clause makes it very clear that the
ClockMaster entity
shall set it’s clockMasterLogSyncInterval to a “value is less than or equal to
the
smallest currentLogSyncInterval (see 10.6.2.3) value for all the ports of the
time-aware
system.”
This clause makes it very clear that each port will send it’s Sync event based
on it’s
configured currentLogSyncInterval.
> > NOTE—The value of initialLogSyncInterval is the value of the sync
> > interval when the port is initialized. The value of the sync
> > interval may be changed, e.g., if the port receives a Signaling
> > message that carries a message interval request TLV (see 10.5.4.3),
> BTW, This part is not (yet) relevant for us, since we don't support
> signaling messages at all.
The point of me adding this clause is the ‘e.g.’. This variable can be changed
on a port-by-port basis by mechanisms such as the signaling TLV, the 802.1AS
defined MIB (defined in section 15), and even a proprietary means such as
a config file.
> > Based on these clauses, it’s clear that each port maintains its own
> > sync interval setting and needs to maintain its own sync interval
> > timer.
> Where in the standard is the operation of the timer specified?
Again, read clauses 10.6.2.3 and 10.6.2.4.
> > It’s also clear that when the slave port of a TAB receives a
> > sync event, that message is not immediately sent out on downstream
> > ports. Rather, the configured sync interval for a given port must be
> > adhered to.
> You say this is clear. Where can I read about this? Is it modeled in
> the state machines somewhere?
Please read section 10.2.11 ‘PortSyncSyncSend state machine’. In the state
diagram (figure 10-8),
refer to the left transition from the ‘SET_SYNC_RECEIPT_TIMEOUT_TIME’ state to
the ‘SEND_MD_SYNC’
state. The transition cannot occur unless 1/2 of the syncInterval time has
elapsed. This state machine
is governed by the given port’s syncInterval.
> Thanks,
> Richard
On 6/7/17, 10:38 AM, "Richard Cochran" <richardcoch...@gmail.com> wrote:
On Wed, Jun 07, 2017 at 02:46:39PM +0000, Rodney Greenstreet wrote:
> Thank you for your feedback. I want to explain why we chose to add TAB to
your BC implementation rather than adding a new type of device. A TAB is
mathematically equivalent to a TC but is functionally equivalent to a BC. More
specifically, a TAB has the following BC attributes:
> - A TAB participates in the BMC selection.
> - A TAB has port state.
> - A TAB has a separate logSyncInterval dataset member for each
port.
>
> It’s the last point that I think needs further clarification.
Sure, there is a per-port value, but this is only relevant when the
port becomes the GM.
> NOTE—The value of initialLogSyncInterval is the value of the sync
> interval when the port is initialized. The value of the sync
> interval may be changed, e.g., if the port receives a Signaling
> message that carries a message interval request TLV (see 10.5.4.3),
BTW, This part is not (yet) relevant for us, since we don't support
signaling messages at all.
> Based on these clauses, it’s clear that each port maintains its own
> sync interval setting and needs to maintain its own sync interval
> timer.
Where in the standard is the operation of the timer specified?
> It’s also clear that when the slave port of a TAB receives a
> sync event, that message is not immediately sent out on downstream
> ports. Rather, the configured sync interval for a given port must be
> adhered to.
You say this is clear. Where can I read about this? Is it modeled in
the state machines somewhere?
Thanks,
Richard
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