A.5 PTP Synchronization
-----------------------
Precision Time Protocol (PTP) provides an efficient way to synchronize
-time on the network nodes. This protocol uses Master-Slave architecture.
-Grandmaster Clock (Master) is a reference clock for the other nodes,
-which adapt their clocks to the master.
+time on the network nodes. This protocol uses Primary-Slave architecture.
+Main Reference Clock (Primary) is a reference clock for the other nodes,
+which adapt their clocks to the Primary.
-Using Physical Hardware Clock (PHC) from the Grandmaster Clock, NIC port
-precision timestamp packets can be served for other network nodes. Slave
-nodes adjust their PHC to the master following the IEEE 1588
+Using Physical Hardware Clock (PHC) from the Main Reference Clock, NIC port
+precision timestamp packets can be served for other network nodes. Secondary
+nodes adjust their PHC to the Primary following the IEEE 1588
specification.
There are existing implementations of PTP protocol that are widely used
----------
This tool handles all PTP traffic on the provided NIC port and updated
-PHC. It also determines the Grandmaster Clock and tracks |br|
-synchronization
+PHC. It also determines the Primary Reference Clock and tracks synchronization
status. This tool can be run as a daemon or as a regular Linux\*
application. When the synchronization is reached, it gives output on the
screen for precision tracking. The configuration file of ptp4l contains
./ptp4l -f ./configs/default.cfg -2 -i <if_name> -m
-The output below shows what the output on non-master node should look
+The output below shows what the output on non-Primary node should look
like when synchronization is started. This means that PHC on this
-machine is synchronized to the master PHC::
+machine is synchronized to the Primary PHC::
ptp4l[1434165.358]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE
ptp4l[1434165.358]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
- ptp4l[1434166.384]: port 1: new foreign master fcaf6a.fffe.029708-1
+ ptp4l[1434166.384]: port 1: new foreign primary fcaf6a.fffe.029708-1
- ptp4l[1434170.352]: selected best master clock fcaf6a.fffe.029708
+ ptp4l[1434170.352]: selected best primary clock fcaf6a.fffe.029708
ptp4l[1434170.352]: updating UTC offset to 37
ptp4l[1434170.352]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
- ptp4l[1434171.763]: master offset -5873 s0 freq -18397 path delay 2778
+ ptp4l[1434171.763]: primary offset -5873 s0 freq -18397 path delay 2778
- ptp4l[1434172.763]: master offset -6088 s2 freq -18612 path delay 2778
+ ptp4l[1434172.763]: primary offset -6088 s2 freq -18612 path delay 2778
ptp4l[1434172.763]: port 1: UNCALIBRATED to SLAVE on
MASTER_CLOCK_SELECTED
- ptp4l[1434173.763]: master offset -5886 s2 freq -24498 path delay 2732
+ ptp4l[1434173.763]: primary offset -5886 s2 freq -24498 path delay 2732
- ptp4l[1434174.763]: master offset 221 s2 freq -20157 path delay 2728
+ ptp4l[1434174.763]: primary offset 221 s2 freq -20157 path delay 2728
- ptp4l[1434175.763]: master offset 1911 s2 freq -18401 path delay 2724
+ ptp4l[1434175.763]: primary offset 1911 s2 freq -18401 path delay 2724
- ptp4l[1434176.763]: master offset 1774 s2 freq -17964 path delay 2728
+ ptp4l[1434176.763]: primary offset 1774 s2 freq -17964 path delay 2728
- ptp4l[1434177.763]: master offset 1198 s2 freq -18008 path delay 2728
+ ptp4l[1434177.763]: primary offset 1198 s2 freq -18008 path delay 2728
- ptp4l[1434178.763]: master offset 746 s2 freq -18101 path delay 2755
+ ptp4l[1434178.763]: primary offset 746 s2 freq -18101 path delay 2755
- ptp4l[1434179.763]: master offset 218 s2 freq -18405 path delay 2792
+ ptp4l[1434179.763]: primary offset 218 s2 freq -18405 path delay 2792
- ptp4l[1434180.763]: master offset 103 s2 freq -18454 path delay 2792
+ ptp4l[1434180.763]: primary offset 103 s2 freq -18454 path delay 2792
- ptp4l[1434181.763]: master offset -13 s2 freq -18540 path delay 2813
+ ptp4l[1434181.763]: primary offset -13 s2 freq -18540 path delay 2813
- ptp4l[1434182.763]: master offset 9 s2 freq -18521 path delay 2813
+ ptp4l[1434182.763]: primary offset 9 s2 freq -18521 path delay 2813
- ptp4l[1434183.763]: master offset 11 s2 freq -18517 path delay 2813
+ ptp4l[1434183.763]: primary offset 11 s2 freq -18517 path delay 2813
phc2sys
-----------
The PHC clock is independent from the system clock. Synchronizing only
-PHC does not make the system clock exactly the same as the master. The
+PHC does not make the system clock exactly the same as the primary. The
xRAN library requires use of the system clock to determine a common
-point in time on two |br|
-machines (O-DU and RU) to start transmission at the
-same moment and keep time frames defined by ORAN Fronthaul |br|
-specification.
+point in time on two machines (O-DU and RU) to start transmission at the
+same moment and keep time frames defined by ORAN Fronthaul specification.
This application keeps the system clock updated to PHC. It makes it
possible to use POSIX timers as a time reference in xRAN application.
Configuration C3 27 can be simulated for O-DU using a separate server
acting as Fronthaul Network and O-RU at the same time. O-RU server can
-be configured to relay PTP and act as PTP master for O-DU. Settings
-below can be used to |br|
-instantiate this scenario. The difference is that
+be configured to relay PTP and act as PTP primary for O-DU. Settings
+below can be used to instantiate this scenario. The difference is that
on the O-DU side, the Fronthaul port can be used as the source of PTP as
well as for U-plane and C-plane traffic.
# Run time options
-1.Start slave port toward PTP GM::
+1.Start secondary port toward PTP GM::
./ptp4l -f ./configs/default_slave.cfg -2 -i enp25s0f0 –m
ptp4l[3904470.275]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
- ptp4l[3904471.085]: port 1: new foreign master fcaf6a.fffe.029708-1
+ ptp4l[3904471.085]: port 1: new foreign primary fcaf6a.fffe.029708-1
- ptp4l[3904475.053]: selected best master clock fcaf6a.fffe.029708
+ ptp4l[3904475.053]: selected best primary clock fcaf6a.fffe.029708
ptp4l[3904475.053]: updating UTC offset to 37
ptp4l[3904475.053]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
- ptp4l[3904477.029]: master offset 196 s0 freq -18570 path delay 1109
+ ptp4l[3904477.029]: primary offset 196 s0 freq -18570 path delay 1109
- ptp4l[3904478.029]: master offset 212 s2 freq -18554 path delay 1109
+ ptp4l[3904478.029]: primary offset 212 s2 freq -18554 path delay 1109
ptp4l[3904478.029]: port 1: UNCALIBRATED to SLAVE on
MASTER_CLOCK_SELECTED
- ptp4l[3904479.029]: master offset 86 s2 freq -18468 path delay 1109
+ ptp4l[3904479.029]: primary offset 86 s2 freq -18468 path delay 1109
- ptp4l[3904480.029]: master offset 23 s2 freq -18505 path delay 1124
+ ptp4l[3904480.029]: primary offset 23 s2 freq -18505 path delay 1124
- ptp4l[3904481.029]: master offset 3 s2 freq -18518 path delay 1132
+ ptp4l[3904481.029]: primary offset 3 s2 freq -18518 path delay 1132
- ptp4l[3904482.029]: master offset -169 s2 freq -18689 path delay 1141
+ ptp4l[3904482.029]: primary offset -169 s2 freq -18689 path delay 1141
2.Synchronize local timer clock on O-RU for sample application::
phc2sys[3904512.268]: CLOCK_REALTIME phc offset -300 s2 freq -38892
delay 1532
-3. Modify configs/default.cfg as shown below to run PTP master on
+3. Modify configs/default.cfg as shown below to run PTP primary on
Fronthaul of O-RU::
diff --git a/configs/default.cfg b/configs/default.cfg
# Run time options
-4.Start PTP master toward O-DU::
+4.Start PTP primary toward O-DU::
./ptp4l -f ./configs/default.cfg -2 -i enp175s0f1 –m
ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES
ptp4l[3903863.734]: selected local clock 3cfdfe.fffe.bd005d as best
- master
+ primary
- ptp4l[3903863.734]: assuming the grand master role
+ ptp4l[3903863.734]: assuming the main reference role
-5.Synchronize local NIC PTP master clock to local NIC PTP slave clock::
+5.Synchronize local NIC PTP primary clock to local NIC PTP secondary clock::
./phc2sys -c enp175s0f1 -s enp25s0f0 -w -m -R 8
6. On O-DU Install PTP for Linux tools from source code the same way as
on O-RU above but no need to apply the patch for msg.c
-7. Start slave port toward PTP master from O-RU using the same
+7. Start secondary port toward PTP primary from O-RU using the same
default_slave.cfg as on O-RU (see above)::
./ptp4l -f ./configs/default_slave.cfg -2 -i enp181s0f0 –m
ptp4l[809092.934]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
- ptp4l[809092.949]: port 1: new foreign master 3cfdfe.fffe.bd005d-1
+ ptp4l[809092.949]: port 1: new foreign primary 3cfdfe.fffe.bd005d-1
- ptp4l[809096.949]: selected best master clock 3cfdfe.fffe.bd005d
+ ptp4l[809096.949]: selected best primary clock 3cfdfe.fffe.bd005d
ptp4l[809096.950]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
requests for current port state and comparing it with the expected
value. This verification should be done before initialization.
-*notes. “SLAVE” is the only expected value in this release; only a
-non-master scenario is supported currently.*
+*notes. “SECONDARY” is the only expected value in this release; only a
+non-primary scenario is supported currently.*
+
+*notes1. Inclusive language terms were used except for the PTP traces where the source code has
+not been updated to support the inclusive language terms yet.*
.. |image0| image:: media/image3.png
:width: 2.52364in
Code Review / o-du / phy.git / blobdiff