3.2. Gigabit PON Standard
The progress in the technology, the need for larger bandwidths and the unquestionable complexity of ATM forced the FSAN group to revise their approach. In the outcome a new standard called Gigabit Passive Optical Network (GPON)23 was released and adopted by ITU in 2003.
The GPON’s functionality is heavily based on its predecessor, although it is no longer reliant on ATM as an underlying protocol. Instead a much simpler Generic Framing Procedure (GFP) is used to provide support for both voice and data oriented services. A big advantage of GPON over other schemes is that interfaces to all the main services are provided and in GFP enabled networks packets belonging to different protocols can be transmitted in their native formats. The functionality is provided which allows seamless interoperability with other GPONs or BPONs. As in modern networks the security of transmitted data is a key issue. A sophisticated mechanism based on Advanced Encryption Standard and a complex exchange of unique keys is built into the
GPON architecture.
Also in comparison with the BPON standard, higher transmission rates are specified making GPON capable of supporting transfer rates of up to 2.48Gbps in the downstream as well as the upstream direction. 3.3. Ethernet PON Standard
The Ethernet Passive Optical Network (EPON) standard has been endorsed by the EFMA. The final version of the new protocol and necessary amendments to the existing ones were accepted by Standard Body and released as IEEE 802.3ah in September 2004. The main goal was to achieve a full compatibility with other Ethernet based networks. Hence, the functionality of Ethernet’s Media Access Control layer is maintained and the extensions are provided to encompass the features of PONs. The achieved solution is simple and straightforward, and the legacy equipment and technologies can be reused similar as in 100BASE–X and 1000BASE–X networks.
