Atom GNSS Timing Configuration
Context
The Atom GNSS module can be inserted only into a GE optical interface. If the Atom GNSS module inserted into a GE optical interface is replaced with a common optical module, all the configurations related to Atom GNSS timing will be deleted.
When an Atom GNSS module is horizontally inserted into a board, no other optical modules can be inserted into the interfaces that are horizontally in parallel to the Atom GNSS module. When an Atom GNSS module is vertically inserted into a board, no other optical modules can be inserted into the interfaces that are vertically in parallel to the Atom GNSS module.
Overview of Atom GNSS
Background
As the commercialization of LTE-TDD and LTE-A accelerates, there is a growing need for time synchronization on base stations. Traditionally, the GNSS (GPS/GLONASS/Beidou) and PTP solutions were used on base stations to implement time synchronization.
The GNSS solution requires GNSS antenna to be deployed on each base station, leading to high TCO. The PTP solution requires 1588v2 support on network-wide devices, resulting in huge costs on network reconstruction for network carriers.
Furthermore, GNSS antenna can properly receive data from GNSS satellites only when they are placed outdoor and meet installation angle requirements. When it comes to indoor deployment, long feeders are in place to penetrate walls, and site selection requires heavy consideration due to high-demanding lightning protection. These disadvantages lead to high TCO and make GNSS antenna deployment challenging on indoor devices. Another weakness is that most indoor equipment rooms are leased, which places strict requirements for coaxial cables penetrating walls and complex application procedure. For example, taking security factors into consideration, the laws and regulations in Japan specify that radio frequency (RF) cables are not allowed to be deployed in rooms by penetrating walls.
To address the preceding challenges, the Atom GNSS timing system is introduced to NE40Es. Specifically, an Atom GNSS module which is comparable to a lightweight BITS device is inserted to an NE40E to provide GNSS access to the bearer network. Upon receipt of GNSS clock signals, the Atom GNSS module converts them into SyncE signals and then sends the SyncE signals to NE40Es. Upon receipt of GNSS time signals, the Atom GNSS module converts them into 1588v2 signals and then sends the 1588v2 signals to base stations. This mechanism greatly reduces the TCO for carriers.
Supported Interface Type
An Atom GNSS module supports only GE optical interfaces and the 1000M full duplex mode. It does not support the adaptive mode.
Supported PTP Device Type
The PTP device type supported by an Atom GNSS module can be boundary clock (BC) or telecom boundary clock(T-BC). A BC or T-BC has multiple clock interfaces. On a BC/T-BC, one interface is used to implement time synchronization with upstream devices, and other interfaces (passive interfaces excluded) are used to transmit time information to downstream devices.
Supported Delay Measurement Mechanism
By default, an Atom GNSS module supports the delay request-response mechanism, which is the PTP link delay measurement mechanism. Configuring this mechanism is not supported.
Supported Packet Encapsulation Mode
The PTP packets sent and received by an Atom GNSS module are encapsulated in Layer 2 multicast mode. Therefore, the PTP packet encapsulation type of NE40E interfaces must be configured as Layer 2 multicast for proper interconnection with an Atom GNSS module.
Configuring the SyncE Function
This section describes how to configure the SyncE function.
Usage Scenario
On the IP RAN shown in Figure 15-1, clock synchronization needs to be achieved between NodeBs. The Atom GNSS timing solution can be deployed as follows to allow clock synchronization: Insert an Atom GNSS module into an ASG so that the Atom GNSS module can synchronize clock signals with the GNSS and the ASG can synchronize clock signals with the Atom GNSS module. Then, configure the SyncE function to allow transmission of clock signals to downstream devices and then to NodeBs. In this manner, network-wide clock synchronization is achieved.
Configuring the SyncE Function on the Device Where an Atom GNSS Module Houses
To achieve network-wide clock synchronization, the SyncE function needs to be configured on the router where the Atom GNSS module houses so that clock signals can be transmitted to downstream devices.
Procedure
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run clock synchronization enable
Clock synchronization is enabled for the interface.
- Run clock priority priority-value
A priority is configured for the clock reference source of the interface.
- Run quit
Return to the system view.
- (Optional) Run clock ssm-control { on | off }
The device is configured whether to select a clock source based on SSM levels.
- (Optional) Run clock run-mode
An Ethernet Equipment Clock (EEC) running mode is configured.
- (Optional) Run clock switch
A clock recovery mode is configured.
- (Optional) Run clock wtr wtr-time
A clock WTR time is configured.
- (Optional) Run clock source-lost holdoff-time
A clock holdoff time upon a timing signal failure is configured.
- (Optional) Run clock max-out-ssm
The maximum output SSM level is configured for the interface clock source.
- (Optional) Run clock freq-deviation-detect enable
Clock frequency offset detection is enabled.
- (Optional) Run clock input-threshold
A lower quality threshold of external clock signals is specified.
Configuring the Time Synchronization Function
This section describes how to configure the time synchronization function.
Usage Scenario
On the IP RAN shown in Figure 15-2, time synchronization needs to be performed between NodeBs. The Atom GNSS timing solution can be deployed as follows to allow time synchronization: Insert an Atom GNSS module into an ASG so that the Atom GNSS module can synchronize clock signals with the GNSS and the ASG can synchronize clock signals with the Atom GNSS module. Then, configure the time synchronization function to allow transmission of clock signals to other devices on the bearer network. In this manner, network-wide clock synchronization is achieved.
Configuring the Time Synchronization Function on an Atom GNSS Module
This section describes how to configure the time synchronization function on an Atom GNSS module so that GNSS time signals can be transmitted to the router where the Atom GNSS module houses through 1588v2 packets and then to downstream devices.
Context
- The class of a clock source cannot be specified. The initial class 248 is used by default when a clock source goes online. After the clock source successfully traces GNSS signals, its class changes to 6 (a device using a class-6 clock source cannot be the secondary devices of other clocks in the clock domain). After the clock source loses track of GNSS signals, its class changes to 248 again.
- The accuracy of a clock source cannot be specified. The initial value 0xFE is used by default when a clock source goes online. After the clock source successfully traces GNSS signals, its accuracy changes to 0x21 (specific to 100 ns). After the clock source loses track of GNSS signals, its class changes to 0xFE again.
- The stability of a clock source cannot be configured. The value is 0xFFFF (if T-GM is not connected to ePRTC).
Perform the following operations on the router where the Atom GNSS module houses:
Procedure
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run smart-clock gnss-model { gps | glonass | beidou | gps-glonass | gps-beidou } [ gps | glonass | beidou | gps-glonass | gps-beidou ] [ gps | glonass | beidou | gps-glonass | gps-beidou ] [ gps | glonass | beidou | gps-glonass | gps-beidou ] [ gps | glonass | beidou | gps-glonass | gps-beidou ]
The mode in which the multi-mode smart clock module on a GE optical interface works is configured.
- Run smart-clock cable-delay delay-value
The feeder delay compensation value for the smart clock module of a GE optical interface is configured.
- (Optional) Run smart-clock leap manual-mode enable
Configure the multi-mode smart clock model on a GE optical interface to obtain leap seconds in manual mode.
- (Optional) Run smart-clock leap current-leap current-leap-value [ { leap59 | leap61 } date date ]
Configure the current leap second value of the multi-mode smart clock module as well as the direction and date of the next leap second adjustment.
- (Optional) Run smart-clock ptp domain domain-value
A clock domain is configured for the Atom GNSS module.
- (Optional) Run smart-clock ptp { priority1 | priority2 } priority-value
Priority 1 or priority 2 of the time source is configured for the Atom GNSS module.
- Run commit
The configuration is committed.
Configuring the 1588v2 Synchronization Function on the router Where an Atom GNSS Module Houses
Configuring 1588v2 globally involves operations such as enabling 1588v2 in the system view and setting the device type to BC. After enabling 1588v2 in the system view, enable it in the interface view. In addition, specify the link delay measurement mechanism, asymmetric correction value, and timestamping mode for the interfaces.
Procedure
- Run system-view
The system view is displayed.
- Run ptp enable
1588v2 is enabled.
- Run ptp device-type bc
The device type is set to BC.
- (Optional) Run ptp domain
A clock domain is configured.
Devices in the same clock domain can exchange 1588v2 packets to synchronize time signal.
- (Optional) Run ptp virtual-clock-id clock-id-value
A virtual clock ID is configured for the BC.
- (Optional) Run ptp asymmetry-measure enable
Automatic asymmetry measurement is enabled for the BC on a 1588v2 ring network.
- (Optional) Run ptp set-port-state enable
Manually specifying the 1588v2 interface status is enabled.
- Run interface interface-type interface-number
The interface view is displayed.
- Run ptp delay-mechanism delay
The delay request-response mechanism is configured.
- Run ptp enable
1588v2 is enabled for the interface.
- (Optional) Run ptp announce-drop enable
The interface is configured to discard Announce messages.
Devices exchange Announce messages to establish the synchronization hierarchy. If an interface is configured to discard Announce messages, the device cannot receive clock synchronization information from other devices through this interface.
- (Optional) Run ptp clock-step one-step
The timestamping mode for 1588v2 packets is set to one-step.
- (Optional) Run ptp passive-measure enable
Performance measurement is enabled for the interface in the passive state.
- (Optional) Run ptp passive-measure alarm-threshold alarm-threshold-value
An alarm threshold of the offset (time difference between slave and master clocks) is configured for the interface in the passive state.
Configuring the G.8275.1 Synchronization Function on the router Where an Atom GNSS Module Houses
You need to enable G.8275.1 on a router in the system view, configure the router as a T-BC, specify the domain to which the router belongs to, and enable the static configuration of the status of the T-BC interface. After enabling G.8275.1 in the system view, you need to enable G.8275.1 in the interface view.
Procedure
- Run system-view
The system view is displayed.
- Run ptp enable
PTP is enabled.
- Run ptp profile g-8275-1 enable
G.8275.1 is enabled.
- Run ptp device-type t-bc
The device type is set to T-BC.
- (Optional) Run ptp domain domain-value
The domain where the device resides is configured.
Devices in the same clock domain can exchange G.8275.1 packets to synchronize time signals.
- (Optional) Run ptp virtual-clock-id clock-id-value
A virtual clock ID is set.
- (Optional) Configure automatic asymmetry measurement for fibers.
- (Optional) Configure the clock source access control function.
- (Optional) Run ptp max-steps-removed
The maximum number of hops for time synchronization is configured. A clock source is considered unavailable if stepsRemoved in the Announce packets received by the clock source is greater than or equal to max-steps-removed-value.
- Run commit
The configuration is committed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run ptp enable
PTP is enabled on the interface.
- (Optional) Run ptp notslave disable
The notslave attribute of the interface is set to FALSE.
- (Optional) Run ptp local-priority local-priority-value
The local priority of a PTP interface is set.
- (Optional) Run ptp asymmetry-correction { negative negative-asymmetry-correction-value | positive positive-asymmetry-correction-value }
The asymmetric correction time for sending G.8275.1 packets on the interface is set.
- (Optional) Run ptp clock-step { one-step | two-step }
The timestamping mode of the synchronization packets sending by the G.8275.1 port is set.
- Run commit
The configuration is committed.
Checking the Configurations
Context
After configuring the SyncE function of the Atom GNSS timing system, check the configurations.
Procedure
- Run the display ptp all [ state | config ] command to check the time synchronization status and configurations of the involved device.
- Run the display ptp interface interface-type interface-number command to check the time synchronization information about the specified interface.
- Run the display smart-clock interface interface-type interface-number command to check information about the Atom GNSS module on the specified interface.
Maintaining Atom GNSS
Atom GNSS timing maintenance includes resetting an Atom GNSS module and enabling self-healing on an Atom GNSS module.
Enabling Self-healing of an Atom GNSS Module
This section describes how to enable self-healing of an Atom GNSS module in response to an IIC watchdog abnormality.
Context
After self-healing is enabled on an Atom GNSS module, the Atom GNSS module is automatically reset, and the SyncE and 1588v2 functions are disabled from the involved interface. After the WTR timer is expired, the SyncE and 1588v2 functions are re-enabled, and services are restored. If self-healing is not enabled, the involved device remains abnormal and waits for user processing.
Perform the following operations on the router where the Atom GNSS module houses:
Configuration Examples for Atom GNSS
This section describes Atom GNSS timing configuration examples.
Example for Configuring Atom GNSS Timing
Networking Requirements
On the IP RAN shown in Figure 15-3, the Atom GNSS timing solution can be deployed to implement clock synchronization and time synchronization between NodeBs. Based on the Atom GNSS timing solution, an Atom GNSS module, which is comparable to a lightweight BITS source, is inserted to an ASG to provide GNSS access for the bearer network. The Atom GNSS module can receive clock and time signals from the GNSS satellite and then convert these signals before sending them to the ASG. The clock signals are converted to SyncE signals and the time signals to 1588v2 signals. The ASG then transmits converted signals to NodeBs through downstream devices. In this manner, network-wide clock synchronization and time synchronization are achieved.
Configuration Roadmap
This section describes Atom GNSS timing configuration only on ASGs. For details about how to configure SyncE to implement clock synchronization for downstream devices of ASGs, see Clock Synchronization Configuration. For details about how to configure 1588v2 to implement time synchronization for downstream devices of ASGs, see 1588v2 Configuration.
The configuration roadmap is as follows:
Configure SyncE.
Configure time synchronization.
Data Preparation
To complete the configuration, you need the following data:
Information about the optical interface to which the Atom GNSS module is inserted
Priority of the clock source
Clock domain
Interface delay measurement mechanism
Procedure
- Configure SyncE on ASG1 and ASG2.
ASG1 configuration is similar to ASG2 configuration. ASG1 configuration is used as an example.
Configure SyncE on the Atom GNSS module.
The SyncE function has been enabled on the Atom GNSS module by default, with no need for manual configuration.Configure SyncE on ASG1 where the Atom GNSS module houses.
# Configure clock source selection based on SSM levels.
<ASG1> system-view
[~ASG1] clock ssm-control on[*ASG1] commit# Enable SyncE and configure priorities for interfaces.
[~ASG1] interface gigabitethernet 1/0/0
[~ASG1-GigabitEthernet1/0/0] clock synchronization enable
[*ASG1-GigabitEthernet1/0/0] clock priority 1
[*ASG1-GigabitEthernet1/0/0] commit
[~ASG1-GigabitEthernet1/0/0] quit
- Configure time synchronization on ASG1 and ASG2.
ASG1 configuration is similar to ASG2 configuration. ASG1 configuration is used as an example.
Configure time synchronization on the Atom GNSS module.
[~ASG1] interface gigabitethernet 1/0/0
[~ASG1-GigabitEthernet1/0/0] smart-clock ptp domain 255
[~ASG1-GigabitEthernet1/0/0] smart clock gnss-model gps glonass
[~ASG1-GigabitEthernet1/0/0] smart-clock cable-delay 60
[*ASG1-GigabitEthernet1/0/0] commit
[~ASG1-GigabitEthernet1/0/0] quit
Configure time synchronization on ASG1 where the Atom GNSS module houses.
# Configure 1588v2 globally.
[*ASG1] ptp enable[*ASG1] ptp device-type bc[*ASG1] ptp domain 255[*ASG1] commit# Configure 1588v2 on interfaces.
[~ASG1] interface gigabitethernet 1/0/0
[*ASG1-GigabitEthernet1/0/0] ptp enable
[~ASG1-GigabitEthernet1/0/0] ptp delay-mechanism delay
[*ASG1-GigabitEthernet1/0/0] commit
[~ASG1-GigabitEthernet1/0/0] quit
- Verify the configuration.
Run the display clock source command to check the status information about all clock sources or the clock source being tracked.
<HUAWEI> display clock source System trace source State: lock mode into pull-in range Current system trace source: bits0 Current 2M-1 trace source: system PLL Current 2M-2 trace source: system PLL Frequency lock success: yes Master board Source Pri(sys/2m-1/2m-2) In-SSM Out-SSM State Ref -------------------------------------------------------------------------- bits0/ 1/---/--- sec dnu normal yes GE1/0/0 2/---/--- sec sec normal yes GE2/0/0 3/---/--- sec sec normal yes
Run the display ptp all command to check whether BITS information has been successfully input.<HUAWEI> display ptp all Device config info ------------------------------------------------------------------------------ PTP state :enabled Domain value :0 Slave only :no Device type :BC Set port state :no Local clock ID :0aa1c6fffe699700 Acl :no Virtual clock ID :no Acr :no Time lock success :no Asymmetry measure :disable Passive measure :disable BMC run info ------------------------------------------------------------------------------ Grand clock ID :0a05d7fffe341500 Receive number :GigabitEthernet1/0/0 Parent clock ID :0a05d7fffe341500 Parent portnumber :35585 Priority1 :128 Priority2 :128 Step removed :0 Clock accuracy :0x31 Clock class :187 Time Source :0xa0 UTC Offset :35 UTC Offset Valid :False Timescale :PTP Time traceable :False Leap :None Frequency traceable :False Offset scaled :0xffff Sync uncertain :False Port info Name State Delay-mech Ann-timeout Type Domain ------------------------------------------------------------------------------ GigabitEthernet1/0/0 slave delay 3 BC 0 Time Performance Statistics(ns): Slot 0 Card 1 Port 5 ------------------------------------------------------------------------------ Realtime(T2-T1) :20942575 Pathdelay :0 Max(T2-T1) :95695479 Min(T2-T1) :20942575 Clock source info Clock Pri1 Pri2 Accuracy Class TimeSrc Signal Switch Direction In-Status ------------------------------------------------------------------------------ local 128 128 0x31 187 0xa0 - - - - bits1/11 128 128 0x20 6 0x20 1pps off in/- normal bits1/12 128 128 0x20 6 0x20 1pps off in/- normal
Configuration Files
ASG1 configuration file
#
sysname ASG1
# clock ssm-control on # ptp enable ptp device-type bc ptp domain 255 # interface gigabitEthernet 1/0/0 clock synchronization enable clock priority 1 smart-clock ptp domain 255 smart clock gnss-model gps glonass smart-clock cable-delay 60 ptp enable ptp delay-mechanism delay #
#
return
ASG2 configuration file
#
sysname ASG2
# clock ssm-control on # ptp enable ptp device-type bc ptp domain 255 # interface gigabitEthernet 1/0/0 clock synchronization enable clock priority 1 smart-clock ptp domain 255 smart clock gnss-model gps glonass smart-clock cable-delay 60 ptp enable ptp delay-mechanism delay #
#
smart clock gnss-model gps glonass smart-clock cable-delay 60return
