Recommendation ITU-T G.984.2 describes a flexible optical fibre access network capable of supporting the bandwidth requirements of business and residential services, and covers systems with nominal line rates of 1 244.160 Mbit/s and 2 488.320 Mbit/s in the downstream direction and 155.520 Mbit/s, 622.080 Mbit/s, 1 244.160 Mbit/s and 2 488.320 Mbit/s in the upstream direction. Both symmetrical and asymmetrical (upstream/downstream) gigabit-capable passive optical network (GPON) systems are described. This Recommendation proposes the physical layer requirements and specifications for the physical media dependent (PMD) layer. The transmission convergence (TC) layer and ranging protocol for GPON systems are described in Recommendation ITU-T G.984.3.