Business class services over a GPON network

A gigabit passive optical network (GPON) network is an attractive way to deliver residential services because it is typically deployed in an unprotected mode, and therefore economical. Typically, businesses are served over a protected network and with tight tolerances of parameters such as jitter and wander. A GPON network can provide the reliability and performance expected for business services, but it must be carefully designed from the outset. Many neighborhoods consist of a mixture of residential homes and small businesses. The businesses are usually interspersed with the residential homes. A GPON network can easily provide an unprotected but economical fiber drop to homes for residential services such as high-speed Internet access or Internet protocol television (IPTV) services. On the other hand, businesses require redundancy for high reliability, and they are willing to pay a premium for their DS1 or DS3 service. The full service access network (FSAN) group's G.984 specification allows for several types of redundancy within the network. However, what this specification doesn't provide for are the network interactions to use this redundancy in an efficient manner. SONET requires a protection switch to take place within 50 ms of a fault condition for minimal impact to services. A GPON network providing businesses services should also be required to switch within a 50 ms window. This is a difficult requirement, but achievable if the network is designed accordingly. Consideration for switching between OLT cards and between ONT fiber ports is a critical part of this reliable network. Another consideration is how much degradation is introduced into the DS1s/E1s as they traverse the network. If multiple adaptations are involved they may introduce unwanted jitter or wander into the network, which could cause slips and other unwanted events leading to a less reliable service. This paper addresses how to provide a reliable GPON network for business service and a cost-effective GPON network for residential service simultaneously. The paper addresses protection mechanisms, DS1/E1 mapping into GPON GEM strategies, and timing and synchronization requirements for providing reliable business services over a GPON network. It also covers various topology methods for providing redundant equipment and facilities for business services and provides a summary of what some of the economic tradeoffs might be for such a network.