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    Clock Sources for ACX Series

    Clocking is an important feature on the ACX Series routers. The ACX Series routers can be directly connected to different types of base stations (for example, base transceiver station (BTS) in 2G, NodeB in 3G, and eNodeB in 4G networks) and different types of routers that hand off time-division multiplexing (TDM, ATM, and Ethernet traffic to the base station controller. ACX Series routers must extract the network clock from these sources and pass on synchronization information to the base stations to help the routers synchronize with the base station controller.

    The ACX Series router timing hardware includes two external clock inputs (BITS and GPS), T1 and E1 ports (FPC 0, PIC 0), Gigabit Ethernet ports (RJ45), Gigabit Ethernet ports (SFP), and 10-Gigabit Ethernet ports.

    Note: ACX500 routers do not support TDM, BITS, ATM, T1 or E1, SONET, and 10-Gigabit Ethernet interfaces.

    ACX Series router hardware and software support various clocking options:

    • The ACX series has an OCXO (Stratum 3E) type of oscillator.

    • External clocking includes PPS, a choice of GPS-based clock recovery (10 MHz), or BITS-T1 or E1 line synchronization (1.544 MHz and 2.048 MHz).

      Note: ACX500 routers do not support 10 MHz in and out. ACX500 routers supports GPS input through SubMiniature version A (SMA) connector.

    • ACX500 routers contain integrated GPS receiver, pulse-per-second (PPS) in and out, and Gigabit Ethernet ports (RJ45 and SFP).

    • Synchronous Ethernet (SyncE) is supported based on the ITU G.8261, G.8262, and G.8264 specifications with line timing for ge and xe ports.

      Synchronous Ethernet is a key requirement for circuit (emulation) services and mobile radio access technologies. 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.

    • The Precision Time Protocol (PTP) 1588v2—compliant ordinary slave clock estimates the time offset from the PTP master clock and tries to align its own time and frequency with that of the master. PTP supports sourcing, transfer of frequency, and phase synchronization. Also, PTP can be used for mobile backhaul when phase synchronization is required, such as in Long Term Evolution-Time Division Duplex (LTE-TDD) infrastructures.

    Modified: 2018-06-10