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Synchronous Ethernet Overview

Synchronization is a key requirement for circuit (emulation) services and mobile radio access technologies. Traditionally, mobile networks utilized SONET/SDH technologies to backhaul voice and data traffic, and used 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 (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.

Table 1 summarizes the first Junos OS release that supports Synchronous Ethernet on the various Juniper Networks routers and their components:

Table 1: Synchronous Ethernet Support on Junos OS

Routers and Components

Junos OS Release

10-Gigabit Ethernet MPC with SFP+ transceivers

11.2R4

MX5, MX10, MX40, and MX80 3D Universal Edge routers with model numbers MX5-T, MX10-T, MX40-T, and MX80-T

11.2R4

On MX240, MX480, and MX960 3D Universal Edge routers, only the following Enhanced MPCs (MPCEs) support Synchronous Ethernet:

  • MPC1E (MX-MPC1E-3D)
  • MPC1E Q (MX-MPC1E-3D-Q)
  • MPC2E (MX-MPC2E-3D)
  • MPC2E Q (MX-MPC2E-3D-Q)
  • MPC2E EQ (MX-MPC2E-3D-EQ)

11.2R4

10-Gigabit Ethernet MIC with XFP in WAN-PHY framing mode

11.2R4

10-Gigabit Ethernet MIC with XFP in LAN-PHY framing mode

11.4

Juniper Networks PTX Series Packet Transport Switches with their 10-Gigabit Ethernet, 40-Gigabit Ethernet, and 100-Gigabit Ethernet interfaces

12.1

Juniper Networks ACX2000 Series Universal Access routers with Gigabit Ethernet and 10-Gigabit Ethernet SFP and SFP+ transceivers.

12.2

The ingress clock monitoring feature is supported on all MX Series routers with the 16x10GE MPC. On these routers, the incoming Synchronous Ethernet signals cannot be monitored on the 16x10GE MPC but are monitored by other Modular Port Concentrators (MPCs) in the chassis. Therefore, you can use the 16x10GE 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 16x10GE 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 16x10GE 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.

Starting with Junos OS Release 12.1, Synchronous Ethernet is supported on Juniper Networks PTX Series Packet Transport Switches. On the packet transport switches, Synchronous Ethernet is supported on 10-Gigabit Ethernet, 40-Gigabit Ethernet, and 100-Gigabit Ethernet interfaces and is compliant with ITU-T G.8261 and ITU-T G.8262 standards.

Starting with Junos OS Release 12.2, Synchronous Ethernet is supported on Juniper Networks ACX Series Universal Access routers with Gigabit Ethernet and 10-Gigabit Ethernet SFP and SFP+ transceivers and is compliant with the ITU-T G.8261 and G.8264 standards.

Synchronous Ethernet is not supported in the following instances:

  • Slot 10 on MX Series router chassis
  • RJ45 ports
  • MPC3E with C form-factor pluggable (CFP) transceiver (CFP)

Note: Unified in-service software upgrade (unified ISSU) is currently not supported when clock synchronization is configured for Synchronous Ethernet on MX80 3D Universal Edge routers and on the MICs and MPCEs on MX240, MX480, and MX960 routers.

 

Related Documentation

 

Published: 2013-03-07

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