Data transmission
The data transmitted over a link is based on an 8-bit/10-bit nonreturn-to-zero
code. For 16G links the data is encoded using
a 64B/66B scheme. In the 8B/10B transmission code, the
high optical power level designates a 1-bit, while the low optical
power level designates a 0-bit. The idle function or one of
the sequence functions is sent repetitively during periods when
information is not being sent. The data-transmission rates on
both multimode and single mode channels are:
- 1.0625 Gbps, which is equivalent to 100 MBytes
- 2.1250 Gbps, which is equivalent to 200 MBytes.
- 4.2500 Gbps, which is equivalent to 400 MBytes.
- 8.5000 Gpbs, which is equivalent to 800 MBytes.
- 14.0250 Gbps, which is equivalent to 1600 MBytes.
- 28.05 Gbps, which is equivalent to 3200 MBytes.
Devices exist that only work at 1.0625 Gbps. Later devices only work at 1.0625 Gbps and 2.125 Gbps. The newest devices that function at 4.25 Gbps also work at the slower data rates. They will autonegotiate with the attached device to choose the fastest common data rate.