Framing is "G-PON like" but uses different wavelengths from G-PON (using a WDM to separate them) so that G-PON subscribers can be upgraded to 10G-PON incrementally while GPON users continue on the original OLT. The G-PON standard is G.98. This compares to the IEEE 802.3av standard for 10G-EPON based on Ethernet, which has standardised upstream rates of both 1Gbps and 10Gbps. The 10 Gigabit PON wavelengths (1577 nm down / 1270 nm up) differ from GPON and EPON (1490 nm down /1310 nm up), allowing it to coexist on the same fibre with either of the Gigabit PONs.
ITU-T Recommendation G.987 is a family that defines this access network standard (referred to as XG-PON). It comprises four recommendations:
Asymmetric 10G-PON is specified as XG-PON1: 10 Gbit/s downstream and 2.5 Gbit/s upstream (nominal line rate of 9.95328 Gbit/s downstream and 2.48832 Gbit/s upstream).
Symmetric 10G-PON is also proposed as XG-PON2 with 10 Gbit/s upstream, but would require burst-mode lasers on ONTs to deliver the upstream transmission speed.