AON is a point-to-point network structure (PTP), each subscriber has their own fiber optic line that is terminated on an optical concentrator. AON can be designed differently, depending on specifications. Usually Metro-Ethernet-Switches, IP-Edge routers or Multi-Service Access Nodes (MSANs) with optical Ethernet interfaces. The fiber optics can be terminated by an ONT too, but also by any Ethernet switch or IP router with an optical uplink interface. If the last mile to the subscriber is to be bridged using copper wire, DSLAMs or other MSANs would be used. When MSANs are used, both copper and optical lines can be used for the last mile from the same access node. The following picture shows some basic components of AON.
AON clearly has the edge because of its flexibility. Due to the static splitting factor and the interfaces on the OLT. AON technology is clearly better regarding to the bandwidth per subscriber. The maximum bandwidth per subscribers is much higher. The flexibility to allocate different bandwidths to individual subscribers is also greater than when PON systems are used. Depending on the splitting factor, a PON connection via fiber optics supplies less bandwidth than a VDSL2 connection via copper wire. The PTP architecture is superior to the PONs PMP architecture. Just by converting boards, subscribers can obtain an upgrade, no network architecture or the service of other subscribers have to change.
Active optical technology is more suitable for private network operators,either by laying their own fiber optic infrastructure, or by using debundled fiber optic lines (Fiber Local Loops). AON is perfect for high-profit end customer segments (such as business customers, multi-dwellings, universities, local authorities etc). As in these cases, flexibility, quality and security are demanded. And because of the way they are structured, PON networks struggle to fulfill these requirements. As standardized ONTs are used, the commercial aspects of supplying households on a large scale should be weighed up too and can compete with PON systems. Nevertheless, as PON networks are on the rise, it is likely that some of the disadvantages of PON listed here will gradually eliminate. However, some of the inherent features of a PON will remain. But what is almost certain is that the fiber optic based access network, and end customer products as well, will constantly be upgraded to handle more than 50 Mbps. The whole issue is set to stay an exciting one.
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