Equipment Redundancy

The first step toward high availability starts with equipping the OLT with redundant components such as Ethernet Switch Units (ESU), Common Controls (function of ESUs), Timings Source, Network Uplinks (from redundant ESUs), Power Plant and Fans. There is also the option for redundant PON Service Modules and/or whole
OLT with Type-B PON redundancy, which will be discussed in more detail later. With a fully equipped duplex OLT, you can benefit from non-service-affecting side-switching, fail-over and/or card-swapping measured at less than 50 msec. Any fail-over of redundantly deployed cards generates an alarm to Tellabs Panorama PON Manager while service remains intact.

Dual Homing to Core Router and WAN

In the main data center of a building or campus, dual homing to the core router is ideal for high-availability services across campus and at remote buildings providing aggregation, resiliency and load balancing purposes. In this architecture, a business can achieve equipment and facility protection at the OLT. The OLT can provide this redundancy across 1 GbE and 10 GbE Ethernet uplinks, and it can be deployed with any standards-based L2 switches and/or L3 routers. In this configuration, high availability is achieved with dual homing to core routers across multiple interfaces distributed across redundant ESUs.

Redundant Passive Optical Network (PON)

A single OLT can be equipped with a redundant PON port or PON card serving one ONT with two paths across a redundant optical plant. This PON equipment-level redundancy, from one OLT, is a means to provide fiber route diversity using the FSAN ITU standard Type-B PON redundancy option. Type-B PON redundancy is a purely passive solution, defined in principle by FSAN ITU standards, and is contingent on deploying 2:x Passive Optical splitters. These highly reliable 2:x optical splitters provide both protection, redundancy and splitting functions in the optical plant. CIOs and IT pros have a great amout of flexibility as to where these splitters can be placed in their optical plant infrastructure. For example, the 2:x Passive Optical splitters can either be positioned for centralized (e.g. near the data center) or distributed (e.g. far from the data center) architectures. These 2:x passive optical splitters support a variety of split ratios, including 2:8, 2:16 and 2:32, dependent on the type and number of ONTs being subtended. They can be sourced from major Layer-1 optics manufacturers.

Redundant Optical Line Terminals (OLT)

Two OLTs at geographically dispersed locations can also be configured to serve one ONT with two paths across a redundant optical plant. Because of this, Type-B PON redundancy provides options for fiber route diversity to different PON ports in the same OLT, different PON cards in the same OLT, and different OLTs in geographically dispersed locations. The use of redundant OLTs in two locations represents the pinnacle of reliability being 99.9999%, as six-nines network availability is the culmination of all redundancy options, including dual homing routers, equipment redundancy and Type-B PON redundancy with fiber route diversity and geographically dispersed OLTs.

PON Path Protection

With PON Path Protection, the system software proactively monitors the path’s health across the network, and if it detects the OLT has lost connectivity to the network, it will automatically switch to protection. This enables the ability to route traffic around a network failure by shifting traffic to the standby PON. PON Path Protection feature adds the capability to detect the failure of major card-level components, and intelligently switch to the optimal path. This ensures uninterrupted traffic flow of real-time and critical business services. It also allows for the failed card to be replaced in a maintenance window without affecting any network uptime availability.