Table of contents

1. Introduction
2. Compilation
3. Installation
4. Usage
5. Config
6. External API

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1. Introduction

synce4l is a software implementation of Synchronous Ethernet (SyncE) according to ITU-T Recommendation G.8264. The design goal is to provide logic to supported hardware by processing Ethernet Synchronization Messaging Channel (ESMC) and control Ethernet Equipment Clock (EEC) on Network Card Interface (NIC).

Application can operate in two mutually exclusive input modes: line or external. Both modes are described in next paragraphs.

The best source selection is done according to ITU-T Recommendations G.781 and G.8264. Two network options are supported: option 1 and option 2.

Table showing priority of quality levels (QLs) in option 1 networks:

Quality Level	Priority*	SSM	Extended SSM**
ePRTC	0	0x2	0x21
PRTC	1	0x2	0x20
PRC	2	0x2	0xFF
SSU-A	3	0x4	0xFF
SSU-B	4	0x8	0xFF
EEC1	5	0xB	0xFF

Table showing priority of quality levels (QLs) in option 2 networks:

Quality Level	Priority*	SSM	Extended SSM**
ePRTC	0	0x1	0x21
PRTC	1	0x1	0x20
PRS	2	0x1	0xFF
STU	3	0x0	0xFF
ST2	4	0x7	0xFF
TNC	5	0x4	0xFF
ST3E	6	0xD	0xFF
EEC2	7	0xA	0xFF
PROV	8	0xE	0xFF

Remark: *Lower number means higher priority

Remark: **If extended SSM is not enabled, it's implicitly assumed as 0xFF

Incoming SyncE frames are processed and best clock source is extracted from the link having the best quality level. synce4l configures such "best quality" port as a source to recover clock for EEC. The recovered QL is broadcasted to all other interfaces then. synce4l can use external 1PPS source attached (GPS or other generator). which will participate in best source selection algorithm for EEC.

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2. Compilation

Makefile rules are included in Makefile and compilation is done using the command:

make synce4l

External library dependencies

A compilation and further usage of synce4l requires following libraries:

• glibc (which includes also required: libm, libpthread, librt)
• libnl-3
• libnl-genl-3

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3. Installation

Use make install target to install synce4l in a system.

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4. Usage

Use -h command line argument to print the help page:

$? ./synce4l -h
usage: synce4l [options]

 ...

 Other Options

 -f [file] read configuration from 'file'
           (config file takes precedence over command line arguments)
 -l [num]  set the logging level to 'num'
           (0: least detailed, 7: most detailed)
 -m        print messages to stdout
 -q        do not print messages to the syslog
 -v        print synce4l version and exit
 -h        print this message and exit

Remark: synce4l requires root privileges since it opens raw sockets.

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5. Config

Configuration file contains three sections:

• global,
• device,
• port.

Global section

This section starts with [global] keyword, consist of configuration items related to a running synce4l instance.

Parameter	Default	Valid values	Description
logging_level	6	0-7	Minimum log level required to appear in a log.
message_tag	None	string	Tag reported in a log.
poll_interval_msec	20	0-500	Sleep time between subsequent SyncE clock polls
smc_socket_path	/tmp/synce4l_socket	string	Full path to socket file for external application communication
use_syslog	1	0, 1	Set to 1 if syslog should be used.
verbose	0	0, 1	Set to 1 to log extra information.

Device section

This section specifies the configuration of a one logical device e.g. 'synce1'. The name is defined by the user. The name has no impact for any functionality except traces. The name must be enclosed in extra angle bracket when defining new device section e.g. []. All ports defined by port sections after the device section will create one SyncE device (until next device section).

Parameter	Default	Valid values	Description
extended_tlv	0	0, 1	Set to 1 to enable extended QL.
network_option	1	1, 2	Network option according to T-REC-G.8264. All devices in SyncE domain should have the same option configured.
recover_time	60	10-720	Seconds indicating the minimum time to recover from the QL-failed state on the port.
get_eec_state_cmd	None	string	Shell command which will be executed by synce4l to acquire current state of a SyncE EEC on the device. The command shall output current state of EEC to stdout.
eec_holdover_value	None	string	Value expected on stdout stream when EEC is in HOLDOVER state, after calling command defined in get_eec_state_cmd
eec_locked_ho_value	None	string	Value expected on stdout stream when EEC is in LOCKED HOLDOVER state, after calling command defined in get_eec_state_cmd
eec_locked_value	None	string	Value expected on stdout stream when EEC is in LOCKED state, after calling command defined in get_eec_state_cmd
eec_freerun_value	None	string	Value expected on stdout stream when EEC is in FREERUN state, after calling command defined in get_eec_state_cmd
eec_invalid_value	None	string	Value expected on stdout stream when EEC is in INVALID state, after calling command defined in get_eec_state_cmd
clock_id	None	0-MAX(u64)	Required when Linux dpll subsystem shall be used to control EEC, it refers to clock_id value of EEC type dpll in the system
module_name	None	string	Required when Linux dpll subsystem shall be used to control EEC, it refers to name of kernel module that registered the dpll device in the system
dnu_prio	0xf	0-0xffff	Required for Autmatic mode dpll device when Linux dpll subsystem is used. Value of priority which shall be set for input pins, when the source is marked as DNU

Port section

Any other section not starting with < (e.g. [eth0]) is the port section. Multiple port sections are allowed. Each port participates in SyncE communication.

Parameter	Default	Valid values	Description
tx_heartbeat_msec	1000	100-3000	Interval between consecutive SyncE frame transmissions (1000ms is recommended).
rx_heartbeat_msec	50	10-500	Interval between consecutive SyncE socket polls (frame receive).
recover_clock_enable_cmd	None	string	Shell command which enables PHY port pointed by this Port section as a source of frequency for the SyncE EEC on this device (required only in "internal_input" mode).
recover_clock_disable_cmd	None	string	Shell command which disables PHY port pointed by this Port section as a source of frequency for the SyncE EEC on this device (required only in "internal_input" mode).
allowed_qls	None	string	List of hex values containing allowed SSM QLs separated by comma (,), other received ones would be discarded - if parameter is not provided, all QLs will be accepted.
allowed_ext_qls	None	string	List of hex values containing allowed extended SSM QLs separated by comma (,), other received ones would be discarded - if parameter is not provided, all QLs will be accepted.
internal_prio	128	0-255	An internal source priority, higher priority (lower value) is used to select a source as better quality in case two sources are considered equal quality

Remark: Please do not use backslashes in config file in 'string' fields - for example do not use it like this: "/sys/kernel/debug/ice/0000\:5e\:00\.0/cgu_state"

External source section

Any other section not starting with { (e.g. {SMA1}) is the external source section. Multiple external source sections are allowed. Each external source participates in best source selection algorithm for EEC

Parameter	Default	Valid values	Description
input_QL	0	0-15, 0x0-0xF	Quality Level (QL) for "external input" mode.
input_ext_QL	0	0-255,0x0-0xFF	Extended Quality Level for "external input" mode.
external_enable_cmd	None	string	Shell command which enables external clock source pointed by this external source section as a source of frequency for the SyncE EEC on this device.
external_disable_cmd	None	string	Shell command which disables external clock source pointed by this external source section as a source of frequency for the SyncE EEC on this device.
board_label	None	string	Used for Linux dpll subsystem based configuration. A label of a pin associated with the external EEC input in Linux dpll subsytem.
panel_label	None	string	Used for Linux dpll subsystem based configuration. A label of a pin associated with the external EEC input in Linux dpll subsytem.
package_label	None	string	Used for Linux dpll subsystem based configuration. A label of a pin associated with the external EEC input in Linux dpll subsytem.
internal_prio	128	0-255	An internal source priority, higher priority (lower value) is used to select a source as better quality in case two sources are considered equal quality

Remark: When dpll subsystem is used, a value of board_label, panel_label or package_label shall be provided, depending on a type of label that given input has registered in Linux dpll subsystem.

Config example

Command based config

[global]
logging_level              7
use_syslog                 0
verbose                    1
message_tag                [synce4l]
smc_socket_path            /tmp/synce4l_socket

[<synce1>]
network_option             1
extended_tlv               1
recover_time               20
eec_get_state_cmd          cat /sys/class/net/eth0/device/dpll_0_state
eec_holdover_value         4
eec_locked_ho_value        3
eec_locked_value           2
eec_freerun_value          1
eec_invalid_value          0

[eth0]
tx_heartbeat_msec          1000
rx_heartbeat_msec          500
recover_clock_enable_cmd   echo 1 0 > /sys/class/net/eth0/device/phy/synce
recover_clock_disable_cmd  echo 0 0 > /sys/class/net/eth0/device/phy/synce
allowed_qls                0x2,0x4,0x8
allowed_ext_qls            0x20,0x21
internal_prio              1

[{SMA1}]
external_enable_cmd        echo 2 1 > /sys/class/net/enp1s0f0/device/ptp/ptp*/pins/SMA1
external_disable_cmd       echo 0 1 > /sys/class/net/enp1s0f0/device/ptp/ptp*/pins/SMA1
input_QL                   0x2
input_ext_QL               0x20
internal_prio              0

Linux dpll based config

[global]
logging_level              7
use_syslog                 0
verbose                    1
message_tag                [synce4l]
smc_socket_path            /tmp/synce4l_socket

[<synce1>]
network_option             1
extended_tlv               1
recover_time               20
clock_id                   0xaabbccffffccbbaa
module_name                ice

[eth0]
tx_heartbeat_msec          1000
rx_heartbeat_msec          500
allowed_qls                0x2,0x4,0x8
allowed_ext_qls            0x20,0x21
internal_prio              1

[{SMA1}]
board_label                SMA1
input_QL                   0x2
input_ext_QL               0x20
internal_prio              0

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6. External API

The Synce4l API facilitates communication with the Synce4l running application using an AF_UNIX socket. Messages are exchanged as a list of TLV messages (Type-Length-Value) over the socket. The TLV structure is defined in synce_external_api.h as the following:

TLV Structure

Enum: synce_manager_type

Defines different message types for the Synce Manager.

• MSG_DEV_NAME (1): Device name.
• MSG_SRC_NAME (2): External clock source name.
• MSG_ERR_MSG (3): Error messgae returned from synce4l.
• MSG_GET_QL (4): Get QL of devide.
• MSG_GET_EXT_QL (5): Get extended QL of device.
• MSG_SET_QL (6): Set QL of external clock source.
• MSG_SET_EXT_QL (7): Set extended QL of external clock source.
• MSG_END_MARKER (8): End marker.

Struct: synce_manager_tlv

Represents a TLV (Type-Length-Value) message.

• type (uint16_t): Enum value from synce_manager_type.
• length (uint16_t): Length of the value field in bytes.
• value (void*): Data of the given length.

Communication

Communication is achieved by packing the synce_manager_tlv structure and sending it as a byte stream to the AF_UNIX socket. Last TLV of any stream shall use the type MSG_END_MARKER. Returned byte stream from synce4l will use same TLV format, and will end by TLV with MSG_END_MARKER type.

Command and response example

Below is command example for getting the QL of device synce1. Command is constructed from 3 TLVs:

1. Type MSG_DEV_NAME with length 6 and value synce1
2. Type MSG_GET_QL with length 0 and null value
3. Type MSG_END_MARKER with length 0 and null value

| TYPE | LEN | VALUE || TYPE | LEN || TYPE | LEN | |---------------------------------------------------------------------| | DEV | 6 | s y n c e 1 || GET | 0 || END | 0 | | 01 00 | 06 00 | 73 79 6E 63 65 31 || 04 00 | 00 00 || 08 00 | 00 00 |

Example response from synce4l. Device synce1 has QL = 2 Response is constructed from 3 TLVs:

1. Type MSG_DEV_NAME with length 6 and value synce1
2. Type MSG_GET_QL with length 1 and value 2
3. Type MSG_END_MARKER with length 0 and null value

| TYPE | LEN | VALUE || TYPE | LEN | VALUE || TYPE | LEN | |-----------------------------------------------------------------------------| | DEV | 6 | s y n c e 1 || GET | 1 | 2 || END | 0 | | 01 00 | 06 00 | 73 79 6E 63 65 31 || 04 00 | 01 00 | 02 || 08 00 | 00 |

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