10Gbps PONs Follow Two PathsFebruary 7, 2017
Author: Loring Wirbel
The International Telecommunication Union (ITU) has defined two distinct paths for passive optical networks that deliver 10Gbps or greater: XGS-PON and NG-PON2. They join early 10G-EPON networks based on IEEE standards. XGS-PON (G.9807.10) provides a straightforward evolution to symmetrical 10Gbps connections. The G.989.2 Amendment 1 standard enhances an existing proposal, NG-PON2, which relies on a combination of time-division multiplexing (TDM) and wave-division multiplexing (WDM) to support four or eight symmetrical 10Gbps links on one fiber.
Easing this apparent bifurcation for faster PONs, both standards rely on a common MAC and PHY base. Broadcom’s dual-mode BCM68620, which sampled in 4Q16, demonstrates the likely response by the dwindling pool of PON-semiconductor vendors. The company offers a single optical-line-termination (OLT) device for both standard symmetrical and “TWDM” 10Gbps PONs.
We see XGS-PON as a useful but tactical play to give service providers a short-term GPON upgrade. Operators that have already implemented 10G-EPON may bypass XGS-PON. The opportunity for XGS-PON is likely to remain for three to five years, after which time FTTH providers will be well on their way to NG-PON2. Nevertheless, it makes sense for Broadcom to add enhanced TC support in its combined BCM68620 device now so that service providers can avoid additional upgrades later.
The role of Verizon and AT&T in encouraging an open NG-PON2 development environment will be critical to expanding the opportunities for silicon and optical-component vendors. Long-term growth will favor NG-PON2, but the success of that standard will depend on reducing component costs and node complexity while preserving its flexibility.
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