This section describes the clocking for the various supported MRMAC configurations. The MRMAC has a high degree of configurability and the large number of available modes. To achieve a successful implementation, care must be taken to satisfy the clocking requirements described further. You are advised to review the Clocking Use Cases section.
The MRMAC features the ability to
dynamically reconfigure ports to different data rates. For example, the MRMAC could be reconfigured during run-time from 4 × 10G
mode to 1 × 100G mode. This type of reconfiguration has clocking implications. In 4 × 10G,
each port can have independent tx_core_clk[3:0] sources. When the MRMAC is reconfigured into 1 × 100GE mode, only
tx_core_clk[0] is used and the remainder tx_core_clk[3:1]
is ignored. If reconfiguration is not required, the relevant clocks can be statically
connected to the MRMAC.