3.3.2. x6 Clock Lines
The x6 clock lines route the clock within a transceiver bank. The x6 clock lines are driven by the master CGB. The master CGB can only be driven by the ATX PLL or the fPLL. Because the CMU PLLs cannot drive the master CGB, the CMU PLLs cannot be used for bonding purposes. There are two x6 clock lines per transceiver bank, one for each master CGB. Any channel within a transceiver bank can be driven by the x6 clock lines.
For bonded configuration mode, the low speed parallel clock output of the master CGB is used and the local CGB within each channel is bypassed. For non-bonded configurations, use the master CGB to provide a high-speed serial clock output to each channel, in case you have multiple channels driven by the same ATX/fPLL, and if the non-bonded channels span across a transceiver bank.
The x6 clock lines also drive the x24 clock lines which route the clocks to the neighboring transceiver banks.