Recommendation¹ ITU-T G.709.3 specifies a set of interoperable FlexO Beyond 100G (B100G) long-reach interfaces. The rates in scope for FlexO-x-<int> are 100G, 200G and 400G (x=1, 2 and 4). The Recommendation specifies the structure using forward error correction codes with a higher coding gain suitable for longer reach applications, and references common elements from [ITU-T G.709.1] and FEC structures from [ITU-T G.709.2].

The optical parameters associated with FlexO B100G long-reach interfaces are provided by application codes, which are specified for 100G in [ITU-T G.698.2] and are expected to be specified for other rates in a future edition of [ITU-T G.698.2].

¹ This Recommendation includes an electronic attachment with the worksheets specified in Appendix III and the test vectors of Annex G.