... | @@ -31,7 +31,28 @@ achieved. |
... | @@ -31,7 +31,28 @@ achieved. |
|
- very tightly-constrained subset of PTP (which, except for Ethernet,
|
|
- very tightly-constrained subset of PTP (which, except for Ethernet,
|
|
supports wireless and Coordinated Shared Networks)
|
|
supports wireless and Coordinated Shared Networks)
|
|
- it is based on, and includes a profile of, PTP (i.e. IEEE 1588-2008)
|
|
- it is based on, and includes a profile of, PTP (i.e. IEEE 1588-2008)
|
|
-
|
|
- topology/network-functionality-wise: an IEEE 802.1AS bridge acts
|
|
|
|
as an PTP boundary clock, and an IEEE 802.1AS end station acts
|
|
|
|
as an ordinary clock \[1\]
|
|
|
|
- synchronization-wise: the manner in which an IEEE 802.1AS bridge
|
|
|
|
transports synchronization is very similar (mathematically
|
|
|
|
equivalent) to the manner in which an PTP peer-to-peer
|
|
|
|
transparent clock (TC) transports synchronization \[1\]
|
|
|
|
- Each bridge measures frequency offset relative to its
|
|
|
|
neighbors; the accumulated frequency offset relative to the
|
|
|
|
GM and the time difference between the arrival of a Sync
|
|
|
|
message on the slave port and the sending of a subsequent
|
|
|
|
Sync message on a master port are used to construct the
|
|
|
|
synchronized time placed in a Follow\_Up message
|
|
|
|
- propagation delays between neighboring bridges and/or end
|
|
|
|
stations are measured using the peer delay mechanism.
|
|
|
|
- The bridge is not required to filter phase as part of
|
|
|
|
transporting synchronization; all phase filtering occurs at
|
|
|
|
endpoints (end stations or bridges that have service
|
|
|
|
interfaces to applications)
|
|
|
|
|
|
|
|
<!-- end list -->
|
|
|
|
|
|
- time synchronization requirement: -/+500ns with reference to
|
|
- time synchronization requirement: -/+500ns with reference to
|
|
network's grandmaster
|
|
network's grandmaster
|
|
- references:
|
|
- references:
|
... | | ... | |