Provided by: isochron_0.9~rc4-1_amd64 
NAME
isochron-rcv - Start an isochron test in the role of a receiver
SYNOPSIS
isochron rcv [OPTIONS]
DESCRIPTION
This command starts a long-running process that listens for connections from an isochron sender, logs
timestamps for the received test packets, and sends the logged data back.
OPTIONS
-h, --help
prints the short help message and exits
-i, --interface <IFNAME>
specify the network interface on which packets will be received
-d, --dmac <MACADDRESS>
specify the destination MAC address used by the application for recognizing test packets. Can be
either unicast or multicast. Necessary only for the L2 transport (plain Ethernet). Optional, the
interface’s unicast MAC address is used by default.
-e, --etype <NUMBER>
specify the EtherType used by the application for recognizing test packets sent using the L2
transport. Optional, defaults to 0xdead.
-P, --stats-port <NUMBER>
specify the TCP port on which the receiver program is listening for incoming connections. This
socket is used for management and statistics. Optional, defaults to port 5000.
-s, --frame-size <NUMBER>
specify the size of test frames. The size is counted from the first octet of the destination MAC
address until the last octet of data before the FCS.
-S, --stats-address <NUMBER>
specify the IP address on which the receiver program is listening for incoming connections. This
socket is used for management and statistics. Supports binding to a given network device using
the address%device syntax (example: --stats-address ::%vrf0). Optional, defaults to ::, with a
fallback to 0.0.0.0 if IPv6 is not available.
-q, --quiet
this option suppresses error messages regarding invalid test packets. Optional, defaults to
false.
-f, --sched-fifo
when set, the program requests the kernel to change its scheduling policy to SCHED_FIFO for the
duration of the test.
-r, --sched-rr
when set, the program requests the kernel to change its scheduling policy to SCHED_RR for the du‐
ration of the test.
-H, --sched-priority <NUMBER>
when either --sched-fifo or --sched-rr is used, the program requests the kernel to change its
scheduling priority for the duration of the test.
-O, --utc-tai-offset <NUMBER>
the program uses the CLOCK_TAI time base for its timers and for all reported timestamps, and this
option specifies the correction in seconds to apply to software timestamps, which are taken by the
kernel in the CLOCK_REALTIME (UTC) time base. If this option is present, isochron will also
change the kernel’s CLOCK_TAI offset to the specified value, to ensure that its timers fire cor‐
rectly. If the option is absent, isochron queries the kernel’s CLOCK_TAI offset and attempts to
use that. If isochron can also query the UTC offset from ptp4l’s TIME_PROPERTIES_DATA_SET using
management messages, it does that and compares that offset to the kernel’s UTC offset. The UTC
offset reported by ptp4l has the highest priority, and if the application detects that this is
different from the kernel’s CLOCK_TAI offset, it changes the kernel offset to the value queried
from ptp4l.
-2, --l2
this option specifies that the plain Ethernet transport should be used for the test packets. Op‐
tional, defaults to true unless the sender overrides this via the management socket.
-4, --l4
this option specifies that the UDP transport should be used for test packets. Optional, defaults
to false unless the sender overrides this via the management socket.
-U, --unix-domain-socket <PATH>
isochron queries ptp4l’s state by creating and sending PTP management messages over a local UNIX
domain socket. This option specifies the path of this socket in the filesystem. Optional, de‐
faults to /var/run/ptp4l.
-N, --domain-number <NUMBER>
this option provides the domainNumber value to be used when constructing PTP management messages
sent to the ptp4l process. It must coincide with the domainNumber used by ptp4l, otherwise it
will not respond to management messages. Optional, defaults to 0.
-t, --transport-specific <NUMBER>
this option provides the transportSpecific value to be used when constructing PTP management mes‐
sages sent to the ptp4l process. It must coincide with the transportSpecific used by ptp4l, oth‐
erwise it will not respond to management messages. Optional, defaults to 0. Note that PTP vari‐
ants such as IEEE 802.1AS/gPTP require this value to be set to a different value such as 1.
-R, --num-readings <NUMBER>
isochron monitors the synchronization quality between the NIC’s PTP Hardware Clock (PHC) and the
system time by successively reading the system time, the PHC time and the system time again, sev‐
eral times in a row, and picking the group of 3 time readouts that took the least amount of time
overall. This option specifies how many readouts should be performed before picking the fastest
one. Optional, defaults to 5.
EXAMPLES
To start an isochron receiver with PTP synchronization:
ip link set eth0 up && ip addr add 192.168.100.2/24 dev eth0
ptp4l -i eth0 -2 -P --step_threshold 0.00002 &
phc2sys -a -rr --step_threshold 0.00002 &
isochron rcv \
--interface eth0 \
--quiet \
--sched-rr \
--sched-priority 98
AUTHOR
isochron was written by Vladimir Oltean <vladimir.oltean@nxp.com>
SEE ALSO
isochron(8) isochron-send(8) isochron-report(1)
COMMENTS
This man page was written using pandoc (http://pandoc.org/) by the same author.
isochron-rcv(8)