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Linux-based GPON SoCs deliver fiber-to-the-home

Sep 29, 2008 — by Eric Brown — from the LinuxDevices Archive — 684 views

PMC-Sierra is shipping new GPON (gigabit Ethernet passive optical networking) system-on-chips (SoCs) for fiber-to-the-home (FTTH) deployments. The second-generation GPON ONT optical network terminator, gateway, and OLT (optical line terminator) products feature PMC-Sierra's Linux-ready GigaPASS architecture, and are available with Linux reference designs, says the company.

With GPON (ITU G.984), a single optical fiber is divided by passive (non-powered) splitters into 32 branches for FTTH residential and business broadband service. Other semiconductor firms offering Linux-ready chips for the GPON market include Freescale, Conexant, and Cavium.

In March 2007, PMC-Sierra shipped a Linux-based PAS65311 GPON ONT hardware/software reference design. An ONT is a high-speed optical network terminator, equivalent to the “modem” in FTTH GPON networks. The optional residential gateway product works closely with the ONT, offering IPv4 or IPv6 routing, quality-of-service, and other advanced bridging and routing services. The OLT, meanwhile, acts as the carrier infrastructure component on the other end of the optical cable.

The previous PAS65311 ONT design was based on the company's venerable PAS6201 SoC for 10/100 Ethernet PON (EPON) networks, but the PAS65800 ONT design moves to the company's new PAS7401 SoC platform. All the newly announced products maintain the foundational “GigaPASS” architecture, which weds multiple hardware packet-processing subsystems to a control-plane processor running Linux or VxWorks. In addition, the designs are available with a range of user interface support, including gigabit Ethernet, Fast Ethernet, MoCA, POTS, USB, and WiFi, says the company.

PAS65802 GPON ONT reference design
(Click to enlarge)


The new PAS65800 ONT design (pictured above in the 65802 model) incorporates an ARM9-based PAS7401 SoC. The processor reduces power consumption to a minimum when not in use and implements power saving techniques that “enable the use of smaller batteries in deployments where lifeline service is required,” claims PMC-Sierra. The PAS7401 integrates a GPON MAC, a VoIP subsystem, and an embedded controller (see diagram below). It also offers a GigaPASS bridge. The design comes in three flavors — 65800, 65801, and 65802 — which offer a variety of GPON functions, QoS bridging, VoIP, SIP, and OMCI, and come with various combinations of interfaces.

PAS7401 block diagram
(Click to enlarge)


The GPON Gateway reference design (see directly below) is equipped with an MSP7162 gateway SoC that has a 32-bit MIPS core clocked to 600MHz, says PMC-Sierra (see farther below for block diagram). Working with the PAS7401, the MSP7162 is said to add gigabit-per-second IPv4 or IPv6 routing, Network Address Translation (NAT), and QoS features. Supplied GPON gateway software includes an RG management application, GPON functions, bridging, routing, NAT, QoS, WiFi, VoIP, SIP, and OMCI, says the company.

GPON gateway reference design
(Click to enlarge)


The PAS65900 OLT line-card reference design (see below) incorporates the new ARM-based PAS5211 SoC (see farther below). The PAS5211 integrates four GPON MACs and a backplane interface of either one 10Gbps port or four 2.5Gbps ports. The SoC also offers a GigaPASS bridge, Dynamic Bandwidth Allocation (DBA) accelerators, and embedded optical supervision cores, says the company. The supplied software includes GPON link management protocols, a low-latency DBA algorithm, and an API layer that is said to be portable to a variety of operating systems and host processors.

PAS65900 GPON OLT reference design
(Click to enlarge)

The new designs are offered with Linux development software based on the GigaPASS architecture. GigaPASS is equipped with multiple hardware-based packet processing engine subsystems that are said to perform classification, queuing, and filtering, with wire-speed throughput at all packet sizes. The subsystems are integrated with a control processor and middleware supporting Linux, the company adds.

Block diagrams for the MSP7162 Gateway SoC (left) and the PAS5211 OLT SoC (right)
(Click on either to enlarge)

Stated Victor Vaisleib, VP and GM of PMC-Sierra's FTTH business unit, “PMC-Sierra's new SoCs and reference designs enable our customers to offer GPON products with differentiated network and power performance at lower cost and shorter time to market.”


The PAS7401, MSP7162 and PAS5211 are sampling now to PMC-Sierra's customers, says the company, and their respective PAS65800, Gateway, and PAS65900 reference designs are said to be available now to leading GPON equipment manufacturers. More information may be found here.

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