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Synchronous Ethernet

SUMMARY Synchronous Ethernet, also referred as SyncE, is an ITU-T standard for computer networking that facilitates the transference of clock signals over the Ethernet physical layer.

Synchronous Ethernet Overview

Synchronous Ethernet (ITU-T G.8261 and ITU-T G.8264) is a physical layer technology that functions regardless of the network load and supports hop-by-hop frequency transfer, where all interfaces on the trail must support Synchronous Ethernet. It enables you to deliver synchronization services that meet the requirements of the present-day mobile network, as well as future Long Term Evolution (LTE)–based infrastructures.

Synchronization is a key requirement for circuit (emulation) services and mobile radio access technologies. Traditionally, mobile networks used SONET/SDH technologies to backhaul voice and data traffic, and the native support for frequency of SONET/SDH to synchronize their radio network. With the need for greater-capacity backhaul networks, packet-based technologies such as Carrier Ethernet (which do not support the transfer of frequency) and wireless technologies such as frequency division duplex and time-division duplex require not only frequency synchronization but also proper time and phase alignment. This requirement is fulfilled by Synchronous Ethernet, which is used for physical layer frequency synchronization of connected access devices (such as base stations, access nodes, and so on). Synchronous Ethernet supports sourcing and transfer of frequency for synchronization purposes for both wireless and wireline services and is primarily used for mobile backhaul and converged transport.

Synchronous Ethernet is used to transfer clock signals over Ethernet interfaces. The Synchronous Ethernet operation is described in three ITU recommendations:

  • G.8261—Defines the architecture and wander performance of Synchronous Ethernet networks.

  • G.8262—Specifies timing characteristics of synchronous Ethernet equipment clock (EEC).

  • G.8264—Describes the Ethernet Synchronization Message Channel (ESMC).

Synchronous Ethernet is not supported in the following instances on an MX Series router:

  • Slot 10 on an MX Series router with Switch Control Board (SCB).

  • RJ45 ports

However, note that Synchronous Ethernet is supported on slot 10 on an MX Series router with SCBE and SCBE2.

Unified in-service software upgrade (unified ISSU) is currently not supported when clock synchronization is configured for PTP and Synchronous Ethernet on MX80 Universal Routing Platforms and on the MICs and MPCEs on MX240, MX480, MX960, MX2010, and MX2020 routers.

The following sections explain Synchronous Ethernet:

Synchronous Ethernet on Routers

Synchronous Ethernet is supported on the ACX Series routers with Gigabit Ethernet and 10-Gigabit Ethernet SFP and SFP+ transceivers and is compliant with ITU-T Recommendation G.8261: Timing and synchronization aspects in packet networks and ITU-T Recommendation G8264: Distribution of timing through packet networks.Synchronous Ethernet is a physical layer frequency transfer technology modeled after synchronization in SONET/SDH. Traditional Ethernet nodes, which do not support Synchronous Ethernet, do not carry synchronization from one node link to another. Synchronous Ethernet–capable nodes however can synchronize their chassis clock to a clock recovered from an interface connected to an upstream clock primary. After this, the clock is used to time data sent to downstream clock slaves, forming a synchronization trail from a Primary Reference Clock (PRC) to Ethernet equipment clocks (EECs) and transferring frequency synchronization along the trail.

The ITU-T G.8264 specification defines the Synchronization Status Message (SSM) protocol and its format for Synchronous Ethernet to ensure interoperability between Synchronous Ethernet equipment used for frequency transfer—for example, SONET/SDH. Synchronous Ethernet provides stable frequency synchronization to a PRC and is not affected by load on the network. However, it requires that all the nodes from the PRC to the last downstream node are Synchronous Ethernet capable. Synchronous Ethernet is a recommended technology for mobile networks that require frequency-only synchronization—for example, 2G or 3G base stations.

Ingress Monitoring on Routers

The ingress clock monitoring feature is supported on all MX Series routers including the 16-port 10-Gigabit Ethernet MPC. On these routers, the incoming Synchronous Ethernet signals cannot be monitored on the 16-port 10-Gigabit Ethernet MPC but are monitored by other Modular Port Concentrators (MPCs) in the chassis. Therefore, you can use the 16-port 10-Gigabit Ethernet MPC for incoming Synchronous Ethernet signals if at least one other MPC with an Ethernet Equipment Clock (EEC) is present in the chassis. This behavior is referred to as ingress clock monitoring. Note that the 16-port 10-Gigabit Ethernet MPC does not have a built-in EEC or internal clock; therefore, it can only input (accept) a clock signal but cannot act as a clock source.

When an MX Series router is configured for Synchronous Ethernet on the 16-port 10-Gigabit Ethernet MPC and no other MPC with an EEC is present in the chassis, the Synchronous Ethernet feature cannot be supported by the system. The system notifies the user through log messages and CLI output and justifies its inability to support Synchronous Ethernet.

For information about Synchronous Ethernet support on the 10-Gigabit Ethernet MIC, see Synchronous Ethernet on 10-Gigabit Ethernet MIC Overview.

Supported Platforms

Synchronous Ethernet (SyncE) summarizes the first Junos OS release that supports Synchronous Ethernet on the various Juniper Networks routers and their components.

Example: Configure Synchronous Ethernet

Requirements

This example uses the following hardware and software components:

  • One MX80-T, MX5-T, MX10-T, MX40-T, MX80, MX240, MX480, or MX960 router

  • Junos OS Release 10.4 or later for MX80 Universal Routing Platforms and 11.2R4 or later for MX80-T, MX5, MX10, MX40, MX240, MX480, and MX960 routers.

Overview

You can configure Synchronous Ethernet on MX5-T, MX10-T, MX40-T, MX80, MX80-T, MX240, MX480, and MX960 routers, which enables you to synchronize clocks between nodes in a network through frequency synchronization.

You can set the values for each parameter according to your requirement. The values given in this example are for illustration purposes only.

Configuration

CLI Quick Configuration

To quickly configure synchronization on the aforementioned routers, copy the following commands, paste them in a text file, remove any line breaks, and then copy and paste the commands into the CLI.

[edit]

set chassis synchronization clock-mode auto-selectset chassis synchronization network-type option-1set chassis synchronization quality-mode-enableset chassis synchronization selection-mode configured-qualityset chassis synchronization switchover-mode revertiveset chassis synchronization hold-interval configuration-change 1 restart 1 switchover 1set chassis synchronization esmc-transmit interfaces ge-2/0/0set chassis synchronization source external-a priority 2 quality-level prc request force-switchset chassis synchronization interfaces ge-2/0/0 priority 1 quality-level prc request force-switch wait-to-restore 1

Procedure

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

For step-by-step configuration, see Configure Clock Synchronization Interface on MX Series Routers.

To configure Synchronous Ethernet, perform the following tasks:

  1. Configure the clock mode, network type, quality mode, selection mode, and switchover mode.

  2. Configure the hold interval for configuration change, restart interval, and the switchover interval in seconds.

  3. Configure the interfaces for transmitting ESMC.

  4. Configure the source node with its quality level, priority, and request type.

  5. Configure the interfaces with priority, quality level, request type, and time to restore the interface to default.

Results

Display the results of the configuration:

Verification

Confirm that the configuration is working properly.

Verify the Basic Parameters for Synchronization

Purpose

Verify that the basic synchronization parameters such as the current clock status, clock locked to, and configured sources are working as expected.

Action

From operational mode, enter the run show chassis synchronization command to display the synchronization details.

Meaning

The output displays the basic synchronization parameters configured on the interface.

Verify All the Parameters for Synchronization

Purpose

Verify that all the synchronization parameters are working as expected.

Action

From operational mode, enter the run show chassis synchronization extensive command to display all the synchronization details.

Meaning

The output displays all the synchronization parameters configured on the interface.

Verify the Global Configuration

Purpose

Verify that all the global configuration parameters are working as expected.

Action

From operational mode, enter the run show synchronous-ethernet global-information command to display the set parameters for the global configuration.

Meaning

The output displays global information about the configured node.

Verify the ESMC Transmit Parameters

Purpose

Verify that the transmission parameters of ESMC on the interface are working as expected.

Action

From operational mode, enter the run show synchronous-ethernet esmc transmit detail command to display the set parameters for the ESMC transmission.

Meaning

The output displays all the transmission details about the configured ESMC interface.

Verify the ESMC Statistics Parameters

Purpose

Verify the statistics related to ESMC on the interface.

Action

From operational mode, enter the run show synchronous-ethernet esmc statistics command to display the statistics for the ESMC transmission.

Meaning

The output displays information about the ESMC statistics.

Verify that the ESMC Statistics are Cleared

Purpose

Clear the statistics related to ESMC on the interface.

Action

From operational mode, enter the clear synchronous-ethernet esmc statistics command to clear the statistics for the ESMC transmission.

Meaning

The output displays the message that the ESMC statistics have been cleared.

Synchronous Ethernet on 10-Gigabit Ethernet MIC Overview

Synchronous Ethernet (ITU-T G.8261) is a physical layer technology that functions regardless of the network load. Synchronous Ethernet supports hop-by-hop frequency transfer, where all interfaces on the trail must support Synchronous Ethernet.

10-Gigabit Ethernet MIC with XFP supports Synchronous Ethernet in LAN-PHY framing mode. This is possible only when all the Physical Interface Cards (PICs) under the given Modular Interface Card (MIC) and its ingress interfaces are configured in LAN framing mode. For more information about configuring LAN framing mode, see Example: Configure Framing Mode for Synchronous Ethernet on MX Series Routers with 10-Gigabit Ethernet MIC. In this mode, the LAN frequency is directly supplied by the MIC's on-board clocking circuitry.

On MX80 Universal Routing Platforms, when the PIC-level framing type is changed, the pluggable MIC (2-port 10-Gigabit Ethernet MIC with XFP) is restarted and the Forwarding Engine Board with the built-in MIC (4-port 10-Gigabit Ethernet MIC with XFP) is restarted.

On MX240, MX480, and MX960 routers, when the PIC-level framing type is changed from LAN mode to non-LAN mode (on a MIC), the entire MPC restarts.

The default interface framing mode is LAN-PHY framing mode. For WAN-PHY framing mode operation, interface framing needs to be set to the wan-phy framing option explicitly. For more information about the interface-level and PIC-level configuration combination, see Example: Configure Framing Mode for Synchronous Ethernet on MX Series Routers with 10-Gigabit Ethernet MIC.

Synchronous Ethernet is not supported in the following instances:

  • MX240, MX480, and MX960 routers with 10-Gigabit Ethernet MICs or 10-Gigabit Ethernet built-in interfaces do not support Synchronous Ethernet or Ethernet Synchronization Message Channel (ESMC) transmit in LAN physical layer device (LAN-PHY) framing mode. To configure Synchronous Ethernet or ESMC transmit interfaces on these routers with 10-Gigabit Ethernet Interfaces, you must configure all the 10-Gigabit Ethernet interfaces on the MIC in WAN physical layer device (WAN PHY) framing mode.

  • Primary and secondary sources cannot be from the same MIC. Alternatively, only the port with the highest quality clock source from a given MIC is used for clock selection.

  • Synchronous Ethernet is not supported on 10-Gigabit Ethernet ports in LAN-PHY mode except for the 10-Gigabit Ethernet MIC with XFP.

  • Prior to Junos OS Release 11.4, Synchronous Ethernet was supported only in WAN-PHY framing mode on the 10-Gigabit Ethernet MICs with XFP.

On the MX Series 5G Universal Routing Platforms, the placement of MICs varies from router to router, the following key points has to be taken into consideration while configuring the MICs:

  • On the fixed MX80 chassis, the MICs (10-Gigabit Ethernet MIC) come preinstalled and cannot be replaced. The MIC is labeled as 0/MIC 0 and it consists of four 10-Gigabit Ethernet ports labeled 0 through 3, left to right.

  • On the modular MX5, MX10, MX40, and MX80 chassis, there are two MIC slots that are labeled as 1/MIC 0 and 1/MIC 1.

  • On the MX240, MX480, and MX960 Universal Routing Platforms, there are two slots for MICs which are labeled as PIC 0/1 and PIC 2/3 on the Modular Port Concentrators (MPCs).

Note that hereon the term PIC is being used in synonymous with the term MIC slot or Ethernet ports (in the case of fixed MX80 chassis).

You can configure a MIC in LAN-PHY framing mode by configuring all the constituent logical PICs in the same LAN-PHY framing mode on MX80, MX240, MX480, and MX960 routers.

You can also alternatively configure a MIC in WAN-PHY framing mode on MX80, MX240, MX480, and MX960 routers by configuring all the constituent logical PICs in the same WAN-PHY framing mode in any one of the following configurations:

  • No framing mode configured on all the constituent logical PICs of the MIC.

  • Incompatible framing mode configured on constituent logical PICs of the MIC.

  • No framing mode configured on some of the constituent logical PICs of the MIC.

All the logical PICs in a single MIC must be configured in the same framing mode.

You can also configure the framing mode at the interface level and at the PIC level. For more information about configuring the framing mode at the PIC level and at the interface level, see Example: Configure Framing Mode for Synchronous Ethernet on MX Series Routers with 10-Gigabit Ethernet MIC.

When the PIC-level framing type is changed between LAN mode and non-LAN mode on a MIC:

  • The Forwarding Engine Board (FEB) is restarted in the case of the built-in MIC (4-port 10-Gigabit Ethernet MIC with XFP) on MX80 routers.

  • Only the corresponding MIC is restarted in the case of the pluggable MIC (2-port 10-Gigabit Ethernet MIC with XFP) on MX80 routers.

  • The entire MPC restarts in the case of MX240, MX480, and MX960 routers.

By default, the PIC-level framing mode is set to WAN framing type, that is, e1 | e3 | sdh | sonet | t1 | t3. Synchronous Ethernet works on the 10-Gigabit Ethernet MIC with XFP in LAN-PHY mode only when the PIC-level framing configuration is configured to the lan framing type explicitly.

By default, the interface-level framing mode is set to lan-phy. For WAN-PHY operation, interface framing needs to be set to wan-phy framing explicitly.

Table 1 summarizes the possible configuration combination for Synchronous Ethernet on the 10-Gigabit Ethernet MIC with XFP that are available at the interface level and the PIC level:

Table 1: Configuration Options

Framing Configuration

Operation

PIC Level

Interface Level

Interface Status

Will Synchronous Ethernet Function?

Will Non-Synchronous Ethernet Functions Work?

LAN

LAN-PHY (Default)

Up

Yes

Yes

LAN

WAN-PHY

Down (Framing Conflict)

No

No

WAN (Default)

LAN-PHY (Default)

Up

No

Yes

WAN (Default)

WAN-PHY

Up

Yes

Yes

The following cases and corresponding behaviors explain Table 1 in detail.

  • The PIC is being brought up online:

    This case is applicable when either the MIC is restarted or when the MIC is being brought online by an operational command. In this case, the behavior can be presented as:

    • No framing mode is configured for any or all of the constituent logical PICs of the MIC—The MIC is configured to operate in WAN-PHY framing mode as the WAN mode is the default mode.

      Here, the WAN-PHY framing-based interfaces operate in normal state and provides Synchronous Ethernet services. However, the LAN-PHY framing-based interfaces operate normally but cannot provide Synchronous Ethernet services.

    • All the constituent logical PICs of a MIC are configured in LAN-PHY mode—The MIC is configured to operate in LAN-PHY framing mode.

      In this scenario, the WAN-PHY framing-based interfaces cannot operate in normal state. As a result, these interfaces are administratively brought down. The reason for the interface being in admin-down state is displayed as Framing Conflict in the output of the show interfaces operational command. This is because the interface framing configuration (WAN-PHY) is in conflict with the PIC-level framing configuration of LAN-PHY. Because the interfaces are in admin-down state, neither the Synchronous Ethernet services nor other services are provided.

      Alternatively, all the LAN-PHY framing-based interfaces can operate in normal state and can continue to provide any of the Synchronous Ethernet services.

  • The PIC is already online:

    • In WAN-PHY framing mode—The interface framing configuration on the PIC has changed from WAN-PHY to LAN-PHY.

      The interface continues to be operational for data transceiving purposes. However, it cannot provide any of the Synchronous Ethernet services.

    • In WAN-PHY framing mode—The interface framing configuration on the PIC has changed from LAN-PHY to WAN-PHY.

      The interface continues to be operational for data transceiving purposes, and it can also provide Synchronous Ethernet services.

    • In LAN-PHY framing mode—The interface framing configuration on the PIC has changed from WAN-PHY to LAN-PHY.

      The interface is operational for data transceiving purposes, and it can also provide Synchronous Ethernet services.

    • In LAN-PHY framing mode—The interface framing configuration on the PIC has changed from LAN-PHY to WAN-PHY.

      The interface is down; therefore, it cannot provide any Synchronous Ethernet services.

Support for Synchronous Ethernet is limited in the following instances:

  • Primary and secondary sources cannot be from the same MIC. Alternatively, only the port with the highest quality clock source from a given MIC is used for clock selection.

  • Prior to Junos OS Release 11.4, Synchronous Ethernet was supported only in WAN-PHY framing mode on the 10-Gigabit Ethernet MICs with XFP.

Example: Configure Framing Mode for Synchronous Ethernet with 10-Gigabit Ethernet MIC

Requirements

This example uses the following hardware and software components:

  • Junos OS Release 11.4 or later for MX80-T, MX240, MX480, or MX960 routers

  • One MX80-T, MX240, MX480, and MX960 router with 10-Gigabit Ethernet MIC with XFP

Overview

You can set the framing mode at the PIC level and at the interface level with various configuration combinations. For more information about the various configuration combinations, see Synchronous Ethernet on 10-Gigabit Ethernet MIC Overview.

This example provides information about configuring framing mode at the interface level and the PIC level for Synchronous Ethernet on the 10-Gigabit Ethernet MIC with XFP.

The 10-Gigabit Ethernet MIC with XFP supports Synchronous Ethernet in LAN-PHY framing mode. This is possible only when all the logical PICs under the given Modular Interface Card (MIC) and its ingress interfaces are configured in LAN framing mode.

You can also alternatively configure a MIC in WAN-PHY framing mode on MX80, MX240, MX480, and MX960 routers by configuring all the constituent logical PICs in the same WAN-PHY framing mode in any one of the following configurations:

  • No framing mode configured on all the constituent logical PICs of the MIC.

  • Incompatible framing mode configured on constituent logical PICs of the MIC.

  • No framing mode configured on some of the constituent logical PICs of the MIC.

By default, the PIC-level framing mode is set to WAN framing type, that is e1 | e3 | sdh | sonet | t1 | t3. Synchronous Ethernet works on 10-Gigabit Ethernet MIC with XFP in LAN-PHY mode only when the PIC level framing configuration is configured to lan framing type explicitly.

By default, the interface-level framing mode is set to lan-phy. For WAN-PHY operation, interface framing needs to be set to wan-phy framing explicitly.

You can set the values for each parameter according to your requirement. The values given in this example are for illustration purposes only.

Configuration

CLI Quick Configuration

To quickly configure PIC-level framing and interface-level framing on the 10-Gigabit Ethernet MIC with XFP, copy the following commands and paste it into the CLI.

[edit]

set chassis fpc 2 pic 0 framing lanset chassis fpc 2 pic 1 framing lanset interfaces xe-2/1/0 framing-mode lan-phy

The following example requires you to navigate various levels in the configuration hierarchy. For instructions on how to do that, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

For step-by-step configuration of Synchronous Ethernet, see Configure Clock Synchronization Interface on MX Series Routers.

Procedure

Step-by-Step Procedure

To configure PIC-level framing on the 10-Gigabit Ethernet MIC with XFP, perform the following tasks:

  1. In configuration mode, go to the [edit chassis] hierarchy level.

  2. Configure the FPC slot and the first PIC slot.

  3. Configure the framing type as LAN on the first PIC slot.

  4. Configure the FPC slot and the second PIC slot.

  5. Configure the framing type as LAN on the second PIC slot.

Step-by-Step Procedure

To configure interface-level framing on the 10-Gigabit Ethernet MIC with XFP, perform the following tasks:

  1. In configuration mode, go to the [edit interfaces] hierarchy level and set the interface as xe-2/1/0.

  2. Configure the interface in LAN-PHY framing mode.

Results

Display the results of the configuration at the PIC level:

Display the results of the configuration at the interface level: