Reverse Path Filters

Reverse path filters, if enabled, can prevent PTP packets from being delivered to the sfptpd process.

If packets are arriving at the PTP interface, but the following message is observed periodically in the sfptpd stats file:

Failed to receive Announce message in 12 seconds

then you must disable the rp_filter on the PTP interface - and (possibly required) all interfaces:

# echo 0 > /proc/sys/net/ipv4/conf/<interface>/rp_filter
# echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter

Also see the Failed to Receive Announce Messages section.