According to 1588, PTP message loops are simply someone else's problem
with respect to transparent clocks. Since we are running the BMCA for
syntonization anyway, we might as well go ahead and implement the spanning
tree for PTP messages.
Signed-off-by: Richard Cochran <richardcoch...@gmail.com>
---
config.c | 1 +
default.cfg | 1 +
port.c | 1 +
ptp4l.8 | 6 ++++++
4 files changed, 9 insertions(+)
diff --git a/config.c b/config.c
index e751d40..748529d 100644
--- a/config.c
+++ b/config.c
@@ -254,6 +254,7 @@ struct config_item config_tab[] = {
GLOB_ITEM_DBL("step_threshold", 0.0, 0.0, DBL_MAX),
GLOB_ITEM_INT("summary_interval", 0, INT_MIN, INT_MAX),
PORT_ITEM_INT("syncReceiptTimeout", 0, 0, UINT8_MAX),
+ GLOB_ITEM_INT("tc_spanning_tree", 0, 1, 1),
GLOB_ITEM_INT("timeSource", INTERNAL_OSCILLATOR, 0x10, 0xfe),
GLOB_ITEM_ENU("time_stamping", TS_HARDWARE, timestamping_enu),
PORT_ITEM_INT("transportSpecific", 0, 0, 0x0F),
diff --git a/default.cfg b/default.cfg
index 142675d..456a995 100644
--- a/default.cfg
+++ b/default.cfg
@@ -40,6 +40,7 @@ path_trace_enabled 0
follow_up_info 0
hybrid_e2e 0
net_sync_monitor 0
+tc_spanning_tree 0
tx_timestamp_timeout 1
use_syslog 1
verbose 0
diff --git a/port.c b/port.c
index e83f44a..23c1f13 100644
--- a/port.c
+++ b/port.c
@@ -2834,6 +2834,7 @@ struct port *port_open(int phc_index,
p->hybrid_e2e = config_get_int(cfg, p->name, "hybrid_e2e");
p->net_sync_monitor = config_get_int(cfg, p->name, "net_sync_monitor");
p->path_trace_enabled = config_get_int(cfg, p->name,
"path_trace_enabled");
+ p->tc_spanning_tree = config_get_int(cfg, p->name, "tc_spanning_tree");
p->rx_timestamp_offset = config_get_int(cfg, p->name, "ingressLatency");
p->rx_timestamp_offset <<= 16;
p->tx_timestamp_offset = config_get_int(cfg, p->name, "egressLatency");
diff --git a/ptp4l.8 b/ptp4l.8
index 83549a8..0a35db2 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -399,6 +399,12 @@ Treat one-step responses as two-step if enabled. It is
used to work around
buggy 802.1AS switches.
The default is 0 (disabled).
.TP
+.B tc_spanning_tree
+When running as a Transparent Clock, increment the "stepsRemoved"
+field of Announce messages that pass through the switch. Enabling
+this option ensures that PTP message loops never form, provided the
+switches all implement this option together with the BMCA.
+.TP
.B tx_timestamp_timeout
The number of milliseconds to poll waiting for the tx time stamp from the
kernel
when a message has recently been sent.
--
2.11.0
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